1. 12 Lecture in physics Homework wave nature of light Optical instruments Theory of Relativity Quantum Theory and Models of Atom Quantum Mechanics of Atoms Molecules and Solids Nuclear Physics and Radioactivity

2. Homework is due 10 December 2014. It is on the web site.

3. Presentations scores, analysis.

4. The wave nature of light Huygens’ principle Interference Thin films interference Atmosphere light scattering Diffraction CD diffraction Dispersion Polarization

5. Dispersive prism In optics, a dispersive prism is a type of optical prism, usually having the shape of a geometrical triangular prism. It is the most widely known type of optical prism, although perhaps not the most common in actual use. Triangular prisms are used to disperse light, that is, to break light up into its spectral components (the colors of the rainbow). This dispersion occurs because the angle of refraction is dependent on the refractive index of a certain material which in turn is slightly dependent on the wavelength of light that is travelling through it. This means that different wavelengths of light will travel at different speeds, and so the light will disperse into the colours of the visible spectrum, with longer wavelengths (red, yellow) being refracted less than shorter wavelengths (violet, blue). This effect can also be used to measure the refractive index of the prism's material with high accuracy. In such a measurement, the prism is placed on the central rotary platform of an optical spectrometer with the incident light beam adjusted such that the refracted beam is at minimum deviation. The refractive index can then be computed using the apex angle and the angle of minimum deviation.opticsoptical prism geometrical triangular prismoptical prism dispersespectralcolors rainbowrefraction refractive indexspectrometerminimum deviation A good mathematical description single-prism dispersion is given by Born and Wolf The case of multiple-prism dispersion is treated by Duarte.BornWolfDuarte Prism dispersion played an important role in understanding the nature of light, through experiments by Sir Isaac Newton and others.Sir Isaac Newton

6. Optical instruments Cameras f-stop = f/D Telescopes Microscopes Lenses Normal lens Telephoto lenses Wide-angle lens Zoom lens Single-lens reflex Circles of confusion Depth of field Picture sharpness

7. Optical instruments (continued) Eye Iris pupil Retina Fovea Cornea Normal eye Nearsightness Farsightness Astigmatism

8. Optical instruments (continued) Underwater vision Magnifying glass Angular magnification Prism Aberrations Chromatic aberration Circle of least confusion Distortion

9. Optical instruments (continued) Resolution Aperture Rayleigh criterion Hubble Space Telescope Lambda limit X-rays Tomography Bragg equation Spying

10. Special Theory of Relativity 1. The laws of physics have the same form in all inertial reference frames 2. Light propagates through empty space with a definite speed c independent of the speed of the source or observer Reference frames Relativity principle Ether Length contraction Time dilation Twin paradox 4-dimensional space-time

11. Special Theory of Relativity (continued) Relativistic momentum Relativistic mass Relativistic velocities addition GPS E = mc 2 E 2 = m 2 c 4 + p 2 c 2

12. Quantum physics

13. Quantum computers

14. Quantum cryptography

15. Early Quantum Theory and Models of Atom

16. Electron discovery

17. Cathode rays

18. Oil-drop experiment The oil drop experiment was an experiment performed by Robert A. Millikan and Harvey Fletcher in 1909 to measure the elementary electric charge (the charge of the electron).experimentRobert A. MillikanHarvey Fletcherelementary electric chargeelectron The experiment entailed balancing the downward gravitational force with the upward drag and electric forces on tiny charged droplets of oil suspended between two metal electrodes. Since the density of the oil was known, the droplets' masses, and therefore their gravitational and buoyant forces, could be determined from their observed radii. Using a known electric field, Millikan and Fletcher could determine the charge on oil droplets in mechanical equilibrium. By repeating the experiment for many droplets, they confirmed that the charges were all multiples of some fundamental value, and calculated it to be 1.5924(17)×10 −19 C, within 1% of the currently accepted value of 1.602176487(40)×10 −19 C. They proposed that this was the charge of a single electron.gravitationaldragelectricelectrodesmechanical equilibriumexperimentC

19. Planck's Hypothesis In 1900 Max Planck proposed a formula for the intensity curve which did fit the experimental data quite well. He then set out to find a set of assumptions -- a model -- that would produce his formula. Instead of allowing energy to be continuously distributed among all frequencies, Planck's model required that the energy in the atomic vibrations of frequency f was some integer times a small, minimum, discrete energy, Emin = hf

20. Planck's Hypothesis (continued) Molecular oscillations are quantized: E=nhf, f is natural frequency of the oscillation

21. Black body A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. A white body is one with a "rough surface [that] reflects all incident rays completely and uniformly in all directions."physical bodyelectromagnetic radiation

22. Quantum In physics, a quantum (plural: quanta) is the minimum amount of any physical entity involved in an interaction. Behind this, one finds the fundamental notion that a physical property may be "quantized," referred to as "the hypothesis of quantization". This means that the magnitude can take on only certain discrete values.physicsphysical propertyquantization A photon is a single quantum of light, and is referred to as a "light quantum". The energy of an electron bound to an atom is quantized, which results in the stability of atoms, and hence of matter in general.electronatom As incorporated into the theory of quantum mechanics, this is regarded by physicists as part of the fundamental framework for understanding and describing nature at the smallest length-scales.quantum mechanics

23. Photon A photon is an elementary particle, the quantum of light and all other forms of electromagnetic radiation, and the force carrier for the electromagnetic force, even when static via virtual photons. The effects of this force are easily observable at both the microscopic and macroscopic level, because the photon has zero rest mass; this allows long distance interactions. Like all elementary particles, photons are currently best explained by quantum mechanics and exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a single photon may be refracted by a lens or exhibit wave interference with itself, but also act as a particle giving a definite result when its position is measured.elementary particlequantumlightelectromagnetic radiationforce carrierelectromagnetic forcestatic virtual photonsforcemicroscopicmacroscopicrest mass interactionsquantum mechanics wave–particle dualitywaves particlesrefracted lenswave interferenceposition

24. Photoelectric effect The photoelectric effect is the observation that many metals emit electrons when light shines upon them. Electrons emitted in this manner can be called photoelectronsmetalselectronslight According to classical electromagnetic theory, this effect can be attributed to the transfer of energy from the light to an electron in the metal. From this perspective, an alteration in either the amplitude or wavelength of light would induce changes in the rate of emission of electrons from the metal. Furthermore, according to this theory, a sufficiently dim light would be expected to show a lag time between the initial shining of its light and the subsequent emission of an electron. However, the experimental results did not correlate with either of the two predictions made by this theoryclassical electromagneticenergyamplitudewavelength

25. Compton scattering Compton scattering is the inelastic scattering of a photon by a quasi-free charged particle, usually an electron. It results in a decrease in energy (increase in wavelength) of the photon (which may be an X-ray or gamma ray photon), called the Compton effect. Part of the energy of the photon is transferred to the recoiling electron. Inverse Compton scattering also exists, in which a charged particle transfers part of its energy to a photon.scatteringphotonchargedelectron energywavelengthX-raygamma rayphoton

26. Pair production Pair production is the creation of an elementary particle and its antiparticle, for example an electron and its antiparticle, the positron, a muon and antimuon, or a tau and antitau. Usually it occurs when a photon interacts with a nucleus, but it can be any other neutral boson, interacting with a nucleus, another boson, or itself. This is allowed, provided there is enough energy available to create the pair – at least the total rest mass energy of the two particles – and that the situation allows both energy and momentum to be conserved. However, all other conserved quantum numbers (angular momentum, electric charge, lepton number) of the produced particles must sum to zero – thus the created particles shall have opposite values of each other. For instance, if one particle has electric charge of +1 the other must have electric charge of −1, or if one particle has strangeness of +1 then another one must have strangeness of −1. The probability of pair production in photon-matter interactions increases with photon energy and also increases approximately as the square of atomic number.elementary particleantiparticleelectronpositronmuon antimuontauantitauphotonnucleusneutralboson energyrest mass energymomentumangular momentumelectric chargelepton numberstrangenessatomic number

27. Wave–particle duality Wave–particle duality is the concept that every elementary particle or quantic entity exhibits the properties of not only particles, but also waves. It addresses the inability of the classical concepts "particle" or "wave" to fully describe the behavior of quantum-scale objects. As Einstein wrote: "It seems as though we must use sometimes the one theory and sometimes the other, while at times we may use either. We are faced with a new kind of difficulty. We have two contradictory pictures of reality; separately neither of them fully explains the phenomena of light, but together they do". elementary particleparticles

28. Annihilation Annihilation is defined as "total destruction" or "complete obliteration" of an object; having its root in the Latin nihil (nothing). A literal translation is "to make into nothing". In physics, the word is used to denote the process that occurs when a subatomic particle collides with its respective antiparticle, such as an electron colliding with a positron, illustrated here. Since energy and momentum must be conserved, the particles are simply transformed into new particles. They do not disappear from existence. Antiparticles have exactly opposite additive quantum numbers from particles, so the sums of all quantum numbers of the original pair are zero. Hence, any set of particles may be produced whose total quantum numbers are also zero as long as conservation of energy and conservation of momentum are obeyed. When a particle and its antiparticle collide, their energy is converted into a force carrier particle, such as a gluon, W/Z force carrier particle, or a photon. These particles are afterwards transformed into other particles.physicssubatomic particleantiparticlequantum numbersconservation of energyconservation of momentumgluonphoton During a low-energy annihilation, photon production is favored, since these particles have no mass. However, high-energy particle colliders produce annihilations where a wide variety of exotic heavy particles are created.photonparticle colliders

29. Complementarity In physics, complementarity is a fundamental principle of quantum mechanics, closely associated with the Copenhagen interpretation. It holds that objects have complementary properties which cannot be measured accurately at the same time. The more accurately one property is measured, the less accurately the complementary property is measured, according to the Heisenberg uncertainty principle. Further, a full description of a particular type of phenomenon can only be achieved through measurements made in each of the various possible bases — which are thus complementary. The complementarity principle was formulated by Niels Bohr, a leading founder of quantum mechanics. quantum mechanics Copenhagen interpretationuncertainty principlephenomenonNiels Bohr

30. Spectral line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from a deficiency or excess of photons in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used as a sort of "atomic fingerprint," as gases emit light at very specific frequencies when exposed to electromagnetic waves, which are displayed in the form of spectral lines. These "fingerprints" can be compared to the previously collected fingerprints of elements, and are thus used to identify the molecular construct of stars and planets which would otherwise be impossible.spectrum

31. Bohr model In atomic physics, the Rutherford–Bohr model or Bohr model, introduced by Niels Bohr in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with attraction provided by electrostatic forces rather than gravity. After the cubic model (1902), the plum-pudding model (1904), the Saturnian model (1904), and the Rutherford model (1911) came the Rutherford–Bohr model or just Bohr model for short (1913). The improvement to the Rutherford model is mostly a quantum physical interpretation of it. The Bohr model has been superseded, but the quantum theory remains sound.atomic physicsNiels Bohratomnucleuselectronssolar systemelectrostatic forcesgravitycubic model plum-pudding modelSaturnian modelRutherford model

32. Stationary state In quantum mechanics, a stationary state is an eigenvector of the Hamiltonian, implying the probability density associated with the wavefunction is independent of time. [1] This corresponds to a quantum state with a single definite energy (instead of a quantum superposition of different energies). It is also called energy eigenvector, energy eigenstate, energy eigenfunction, or energy eigenket. It is very similar to the concept of atomic orbital and molecular orbital in chemistry, with some slight differencesquantum mechanics eigenvectorHamiltonian probability density wavefunction [1]quantum statequantum superpositioneigenketatomic orbitalmolecular orbital

33. Quantum number Quantum numbers describe values of conserved quantities in the dynamics of a quantum system. In the case of quantum numbers of electrons, they can be defined as "The sets of numerical values which give acceptable solutions to the Schrödinger wave equation for the Hydrogen atom". Perhaps the most important aspect of quantum mechanics is the quantization of observable quantities, since quantum numbers are discrete sets of integers or half-integers, although they could approach infinity in some cases. This is distinguished from classical mechanics where the values can range continuously. Quantum numbers often describe specifically the energy levels of electrons in atoms, but other possibilities include angular momentum, spin, etc. Any quantum system can have one or more quantum numbers; it is thus difficult to list all possible quantum numbers.quantum systemSchrödinger wave equation Hydrogenatomquantum mechanicsquantizationdiscrete sets of integersinfinity classical mechanicsenergy levelselectrons atomsangular momentumspin

34. Ground state The ground state of a quantum mechanical system is its lowest-energy state; the energy of the ground state is known as the zero-point energy of the system. An excited state is any state with energy greater than the ground state. The ground state of a quantum field theory is usually called the vacuum state or the vacuum.quantum mechanicalenergy statezero-point energyexcited statequantum field theoryvacuum statevacuum If more than one ground state exists, they are said to be degenerate. Many systems have degenerate ground states. Degeneracy occurs whenever there exists a unitary operator which acts non-trivially on a ground state and commutes with the Hamiltonian of the system.degenerateunitary operatorcommutesHamiltonian According to the third law of thermodynamics, a system at absolute zero temperature exists in its ground state; thus, its entropy is determined by the degeneracy of the ground state. Many systems, such as a perfect crystal lattice, have a unique ground state and therefore have zero entropy at absolute zero. It is also possible for the highest excited state to have absolute zero temperature for systems that exhibit negative temperature.third law of thermodynamicsabsolute zerotemperatureentropycrystal latticeabsolute zerotemperaturenegative temperature

35. Excited state Excitation is an elevation in energy level above an arbitrary baseline energy state. In physics there is a specific technical definition for energy level which is often associated with an atom being excited to an excited state.energy level In quantum mechanics an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). The temperature of a group of particles is indicative of the level of excitation (with the notable exception of systems that exhibit Negative temperature).quantum mechanicsatom moleculenucleusquantum state energyground statetemperatureNegative temperature The lifetime of a system in an excited state is usually short: spontaneous or induced emission of a quantum of energy (such as a photon or a phonon) usually occurs shortly after the system is promoted to the excited state, returning the system to a state with lower energy (a less excited state or the ground state). This return to a lower energy level is often loosely described as decay and is the inverse of excitation.spontaneous induced emissionphotonphonon

36. Matter wave All matter can exhibit wave-like behaviour. For example a beam of electrons can be diffracted just like a beam of light or a water wave. Matter waves are a central part of the theory of quantum mechanics, an example of wave–particle duality. The concept that matter behaves like a wave is also referred to as the de Broglie hypothesis (/dəˈbrɔɪ/) due to having been proposed by Louis de Broglie in 1924. Matter waves are often referred to as de Broglie waves.matterwaveelectronsdiffractedquantum mechanicswave–particle duality/dəˈbrɔɪ/Louis de Broglie

37. Electron microscope

38. Atomic models

39. Atomic spectra

40. Rydberg constant

41. Balmer series Lyman series Paschen series

42. Photosynthesis chemical equation 6CO 2 + 6H 2 O ------> C 6 H 12 O 6 + 6O 2 Sunlight energy Where: CO 2 = carbon dioxide H 2 O = water Light energy is required C 6 H 12 O 6 = glucose O 2 = oxygen

43. Tλ = 3×10 -3 mK

44. h = 7×10 -24 Js

45. E=hf

46. E=nhf

47. de Broglie wave length λ = h/p

48. Compton effect λ' = λ + (1 – cosA)h/(mc)

49. Exercises 41. The Sun’s surface temperature: Estimate the surface temperature of our Sun, given that the Sun emits light whose peak intensity occurs in the visible spectrum at around 500 nm. 42. Star color: Suppose a star has a surface temperature of 32,500 K. What color would this star appear? 43. Calculate the energy of a photon of blue light (λ = 450 nm) in the air or in vacuum.

50. Exercises (continued) 44. Estimate how many visible light photons a 100-W light bulb emits per second. The efficiency of the bulb is 3%, the rest of the energy goes to heat. 45. Photon momentum and force: 10 19 photons emitted per second from 100-W light bulb are focused on the peace of black paper and absorbed. Calculate the momentum of one photon and estimate the force all these photons can exert on the paper.

51. Exercises (continued) 46. Photosynthesis: Nine photons are needed to transform one molecule of CO 2 to the carbohydrate and O 2. The light wavelength is 700 nm. The inverse chemical reaction releases energy of 5 eV/ molecule of CO 2. How efficient is the photosynthesis process? 47. X-ray scattering: X-rays of wavelength 0.140 nm are scattered from a very thin slice of carbon. What will be the wavelengths of X-rays scattered at (a) 0 degrees, (b) 90 degrees, (c) 180 degrees?

52. Exercises (continued) 48. Pair production: (a) What is the minimum energy of a photon that can produce an electron-positron pair? (b) What is this photon’s wavelength? 49. Wavelength of a ball: Calculate the de Broglie wavelength of a 0.2 kg ball moving with a speed of 15 m/s. 50. Wavelength of an electron: Determine the wavelength of an electron that has been accelerated through the potential difference of 100 V.

53. Exercises (continued) 51. As a particle travels faster, does its de Broglie wavelength decrease, increase, or remain the same? 52. Wavelength of a Balmer line: Determine the wavelength of light emitted when a hydrogen atom makes a transition from n = 6 to n = 2 energy level according to the Bohr model.

54. Quantum Mechanics of Atoms

55. Quantum mechanics Quantum mechanics (QM; also known as quantum physics, or quantum theory) is a fundamental branch of physics which deals with physical phenomena at nanoscopic scales where the action is on the order of the Planck constant. It departs from classical mechanics primarily at the quantum realm of atomic and subatomic length scales. Quantum mechanics provides a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. Quantum mechanics provides a substantially useful framework for many features of the modern periodic table of elements including the behavior of atoms during chemical bonding and has played a significant role in the development of many modern technologies.quantum physicsphysicsnanoscopic scalesactionPlanck constantclassical mechanicsquantum realm atomicsubatomicenergymatterperiodic table of elementsatoms chemical bonding

56. Uncertainty principle In quantum mechanics, the uncertainty principle is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle known as complementary variables, such as position x and momentum p, can be known simultaneously. For instance, in 1927, Werner Heisenberg stated that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa.quantum mechanicscomplementary positionmomentumWerner Heisenberg

57. Coordinate-Momentum Uncertainty Principle xp > h/(2π)

58. Time-Energy Uncertainty Principle Et > h/(2π)

59. Vacuum energy may be infinite

60. Quantum number Quantum numbers describe values of conserved quantities in the dynamics of a quantum system. In the case of quantum numbers of electrons, they can be defined as "The sets of numerical values which give acceptable solutions to the Schrödinger wave equation for the Hydrogen atom". Perhaps the most important aspect of quantum mechanics is the quantization of observable quantities, since quantum numbers are discrete sets of integers or half-integers, although they could approach infinity in some cases. This is distinguished from classical mechanics where the values can range continuously. Quantum numbers often describe specifically the energy levels of electrons in atoms, but other possibilities include angular momentum, spin, etc. Any quantum system can have one or more quantum numbers; it is thus difficult to list all possible quantum numbers.quantum systemSchrödinger wave equation Hydrogenatomquantum mechanicsquantizationdiscrete sets of integersinfinity classical mechanicsenergy levelselectrons atomsangular momentumspin

61. Principal quantum number The principal quantum number, symbolized as n, is the first of a set of quantum numbers (which includes: the principal quantum number, the azimuthal quantum number, the magnetic quantum number, and the spin quantum number) of an atomic orbital. The principal quantum number can only have positive integer values. As n increases, the orbital becomes larger and the electron spends more time farther from the nucleus. As n increases, the electron is also at a higher potential energy and is therefore less tightly bound to the nucleus. This is the only quantum number introduced by the Bohr model.quantum numbersazimuthal quantum numbermagnetic quantum numberspin quantum numberatomic orbitalinteger For an analogy, one could imagine a multistoried building with an elevator structure. The building has an integer number of floors, and a (well-functioning) elevator which can only stop at a particular floor. Furthermore the elevator can only travel an integer number of levels. As with the principal quantum number, higher numbers are associated with higher potential energy. Beyond this point the analogy breaks down; in the case of elevators the potential energy is gravitational but with the quantum number it is electromagnetic. The gains and losses in energy are approximate with the elevator, but precise with quantum state. The elevator ride from floor to floor is continuous whereas quantum transitions are discontinuous. Finally the constraints of elevator design are imposed by the requirements of architecture, but quantum behavior reflects fundamental laws of physics.discontinuous

62. (Orbital) Azimuthal quantum number The azimuthal quantum number is a quantum number for an atomic orbital that determines its orbital angular momentum and describes the shape of the orbital. The azimuthal quantum number is the second of a set of quantum numbers which describe the unique quantum state of an electron (the others being the principal quantum number, following spectroscopic notation, the magnetic quantum number, and the spin quantum number). It is also known as the orbital angular momentum quantum number, orbital quantum number or second quantum numberquantum numberatomic orbital orbital angular momentumquantum stateprincipal quantum numberspectroscopic notationmagnetic quantum numberspin quantum number

63. Magnetic quantum number In atomic physics, the magnetic quantum number is the third of a set of quantum numbers (the principal quantum number, the azimuthal quantum number, the magnetic quantum number, and the spin quantum number) which describe the unique quantum state of an electron and is designated by the letter m. The magnetic quantum number denotes the energy levels available within a subshell.atomic physicsquantum numbersprincipal quantum number azimuthal quantum numberspin quantum numberquantum state

64. Spin quantum number In atomic physics, the spin quantum number is a quantum number that parameterizes the intrinsic angular momentum (or spin angular momentum, or simply spin) of a given particle. The spin quantum number is the fourth of a set of quantum numbers (the principal quantum number, the azimuthal quantum number, the magnetic quantum number, and the spin quantum number), which describe the unique quantum state of an electron and is designated by the letter s. It describes the energy, shape and orientation of orbitals.atomic physics quantum numberparameterizes angular momentumspinparticlequantum numbersprincipal quantum numberazimuthal quantum numbermagnetic quantum numberquantum state

65. Zeeman effect The Zeeman effect (/ˈzeɪmən/; IPA: [ˈzeːmɑn]), named after the Dutch physicist Pieter Zeeman, is the effect of splitting a spectral line into several components in the presence of a static magnetic field. It is analogous to the Stark effect, the splitting of a spectral line into several components in the presence of an electric field. Also similar to the Stark effect, transitions between different components have, in general, different intensities, with some being entirely forbidden (in the dipole approximation), as governed by the selection rules./ˈzeɪmən/[ˈzeːmɑn]DutchPieter Zeemanspectral linemagnetic fieldStark effectelectric fielddipoleselection rules Since the distance between the Zeeman sub-levels is a function of the magnetic field, this effect can be used to measure the magnetic field, e.g. that of the Sun and other stars or in laboratory plasmas. The Zeeman effect is very important in applications such as nuclear magnetic resonance spectroscopy, electron spin resonance spectroscopy, magnetic resonance imaging (MRI) and Mössbauer spectroscopy. It may also be utilized to improve accuracy in atomic absorption spectroscopy. A theory about the magnetic sense of birds assumes that a protein in the retina is changed due to the Zeeman effect.Sun starsplasmasnuclear magnetic resonanceelectron spin resonancemagnetic resonance imagingMössbauer spectroscopyatomic absorption spectroscopymagnetic sense When the spectral lines are absorption lines, the effect is called inverse Zeeman effect.

66. Fine structure In atomic physics, the fine structure describes the splitting of the spectral lines of atoms due to quantum- mechanical (electron spin) and relativistic corrections.atomic physicsspectral linesatomselectron spin The gross structure of line spectra is the line spectra predicted by the quantum mechanics of non-relativistic electrons with no spin. For a hydrogenic atom, the gross structure energy levels only depend on the principal quantum number n. However, a more accurate model takes into account relativistic and spin effects, which break the degeneracy of the energy levels and split the spectral lines.hydrogenicprincipal quantum numberdegeneracy

67. Selection rule In physics and chemistry, a selection rule, or transition rule, formally constrains the possible transitions of a system from one quantum state to another. Selection rules have been derived for electronic, vibrational, and rotational transitions in molecules. The selection rules may differ according to the technique used to observe the transition.physicschemistryquantum state electronicvibrationalrotationalmolecules

68. Pauli exclusion principle The Pauli exclusion principle is the quantum mechanical principle that says that two identical fermions (particles with half-integer spin) cannot occupy the same quantum state simultaneously. In the case of electrons, it can be stated as follows: it is impossible for two electrons of a poly-electron atom to have the same values of the four quantum numbers (n, ℓ, m ℓ and m s ). For two electrons residing in the same orbital, n, ℓ, and m ℓ are the same, so m s must be different and the electrons have opposite spins. This principle was formulated by Austrian physicist Wolfgang Pauli in 1925.quantum mechanicalidenticalfermionsspinquantum stateelectronsquantum numbersorbitalelectronsWolfgang Pauli A more rigorous statement is that the total wave function for two identical fermions is anti-symmetric with respect to exchange of the particles. This means that the wave function changes its sign if the space and spin co- ordinates of any two particles are interchanged.wave function fermions Integer spin particles, bosons, are not subject to the Pauli exclusion principle: any number of identical bosons can occupy the same quantum state, as with, for instance, photons produced by a laser and Bose–Einstein condensate.bosonslaserBose–Einstein condensate

69. Fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. The most striking examples of fluorescence occur when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, and the emitted light is in the visible region.lightelectromagnetic radiationluminescencewavelength ultravioletspectrum Fluorescence has many practical applications, including mineralogy, gemology, chemical sensors (fluorescence spectroscopy), fluorescent labelling, dyes, biological detectors, cosmic-ray detection, and, most commonly, fluorescent lamps. Fluorescence also occurs frequently in nature in some minerals and in various biological states in many branches of the animal kingdom.mineralogy gemologyfluorescence spectroscopyfluorescent labellingdyesfluorescent lamps

70. Phosphorescent

71. Metastability Aggregated systems of subatomic particles described by quantum mechanics (quarks inside nucleons, nucleons inside atomic nuclei, electrons inside atoms, molecules or atomic clusters) are found to have many distinguishable states. Of these, one (or a small degenerate set) is indefinitely stable: the ground state or global minimum.subatomic particlesquantum mechanicsquarks nucleonsatomic nucleielectronsatomsmoleculesatomic clustersdegenerate setground stateglobal minimum All other states besides the ground state (or those degenerate with it) have higher energies.

72. Laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation". [1][2] A laser differs from other sources of light because it emits light coherently. Spatial coherence allows a laser to be focused to a tight spot, enabling applications like laser cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over long distances (collimation), enabling applications such as laser pointers. Lasers can also have high temporal coherence which allows them to have a very narrow spectrum, i.e., they only emit a single color of light. Temporal coherence can be used to produce pulses of light—as short as a femtosecond.lightoptical amplificationstimulated emissionelectromagnetic radiationacronym [1][2]coherentlySpatial coherencelaser cutting lithographycollimationlaser pointerstemporal coherencespectrum pulsesfemtosecond Lasers have many important applications. They are used in common consumer devices such as optical disk drives, laser printers, and barcode scanners. Lasers are used for both fiber-optic and free-space optical communication. They are used in medicine for laser surgery and various skin treatments, and in industry for cutting and welding materials. They are used in military and law enforcement devices for marking targets and measuring range and speed. Laser lighting displays use laser light as an entertainment medium.optical disk driveslaser printersbarcode scannersfiber-opticfree-space optical communication laser surgeryweldinglaw enforcementmeasuring rangeLaser lighting displays

73. Holography Holography is a technique which enables three- dimensional images (holograms) to be made. It involves the use of a laser, interference, diffraction, light intensity recording and suitable illumination of the recording. The image changes as the position and orientation of the viewing system changes in exactly the same way as if the object were still present, thus making the image appear three-dimensional.three- dimensionallaserinterferencediffractionintensity three-dimensional The holographic recording itself is not an image; it consists of an apparently random structure of either varying intensity, density or profile.

74. Moseley's law Moseley's law is an empirical law concerning the characteristic x-rays that are emitted by atoms. The law was discovered and published by the English physicist Henry Moseley in 1913. It is historically important in quantitatively justifying the conception of the nuclear model of the atom, with all, or nearly all, positive charges of the atom located in the nucleus, and associated on an integer basis with atomic number. Until Moseley's work, "atomic number" was merely an element's place in the periodic table, and was not known to be associated with any measureable physical quantity. Moseley was able to show that the frequencies of certain characteristic X-rays emitted from chemical elements are proportional to the square of a number which was close to the element's atomic number; a finding which supported van den Broek and Bohr's model of the atom in which the atomic number is the same as the number of positive charges in the nucleus of the atom.empirical lawx-raysatomsHenry Moseleyatomic numbervan den BroekBohr

75. Operators of physical quantities, not physical quantities

76. Wave function A wave function or wavefunction (also named a state function) in quantum mechanics describes the quantum state of a system of one or more particles, and contains all the information about the system considered in isolation. Quantities associated with measurements, such as the average momentum of a particle, are derived from the wavefunction by mathematical operations that describe its interaction with observational devices. Thus it is a central entity in quantum mechanics. The most common symbols for a wave function are the Greek letters ψ or Ψ (lower-case and capital psi). The Schrödinger equation determines how the wave function evolves over time, that is, the wavefunction is the solution of the Schrödinger equation. The wave function behaves qualitatively like other waves, like water waves or waves on a string, because the Schrödinger equation is mathematically a type of wave equation. This explains the name "wave function", and gives rise to wave–particle duality. The wave of the wave function, however, is not a wave in physical space; it is a wave in an abstract mathematical "space", and in this respect it differs fundamentally from water waves or waves on a string.quantum mechanicsquantum statemomentumpsiSchrödinger equationwaveswater waveswave equationwave–particle duality

77. Probability

78. Eigenvalues

79. Electron can be in many places at the same time

80. No trajectories

81. No mechanical spin

82. Schrödinger's cat Schrödinger's cat is a thought experiment, sometimes described as a paradox, devised by Austrian physicist Erwin Schrödinger in 1935. It illustrates what he saw as the problem of the Copenhagen interpretation of quantum mechanics applied to everyday objects. The scenario presents a cat that may be both alive and dead, this state being tied to an earlier random event. Although the original "experiment" was imaginary, similar principles have been researched and used in practical applications. The thought experiment is also often featured in theoretical discussions of the interpretations of quantum mechanics. In the course of developing this experiment, Schrödinger coined the term Verschränkung (entanglement).thought experimentparadoxErwin SchrödingerCopenhagen interpretationquantum mechanics randominterpretations of quantum mechanicsentanglement

83. Schrödinger equation In quantum mechanics, the Schrödinger equation is a partial differential equation that describes how the quantum state of a physical system changes with time. It was formulated in late 1925, and published in 1926, by the Austrian physicist Erwin Schrödinger.quantum mechanicspartial differential equationquantum state physical systemErwin Schrödinger In classical mechanics, the equation of motion is Newton's second law, (F = ma), used to mathematically predict what the system will do at any time after the initial conditions of the system. In quantum mechanics, the analogue of Newton's law is Schrödinger's equation for a quantum system (usually atoms, molecules, and subatomic particles whether free, bound, or localized). It is not a simple algebraic equation, but in general a linear partial differential equation, describing the time-evolution of the system's wave function (also called a "state function").classical mechanicsequation of motionNewton's second lawlinearpartial differential equationwave function

84. Schrödinger equation (continued) The concept of a wavefunction is a fundamental postulate of quantum mechanics. Schrödinger's equation is also often presented as a separate postulate, but some authors assert it can be derived from symmetry principles. Generally, "derivations" of the SE demonstrate its mathematical plausibility for describing wave–particle duality.postulate of quantum mechanicswave–particle duality In the standard interpretation of quantum mechanics, the wave function is the most complete description that can be given to a physical system. Solutions to Schrödinger's equation describe not only molecular, atomic, and subatomic systems, but also macroscopic systems, possibly even the whole universe. The Schrödinger equation, in its most general form, is consistent with either classical mechanics or special relativity, but the original formulation by Schrödinger himself was non-relativistic.standard interpretation of quantum mechanicsmolecularatomic subatomicmacroscopic systems universespecial relativity The Schrödinger equation is not the only way to make predictions in quantum mechanics - other formulations can be used, such as Werner Heisenberg's matrix mechanics, and Richard Feynman's path integral formulation.Werner Heisenberg matrix mechanicsRichard Feynmanpath integral formulation

85. Dirac equation In particle physics, the Dirac equation is a relativistic wave equation derived by British physicist Paul Dirac in 1928. In its free form, or including electromagnetic interactions, it describes all spin-½ massive particles, for which parity is a symmetry, such as electrons and quarks, and is consistent with both the principles of quantum mechanics and the theory of special relativity, and was the first theory to account fully for special relativity in the context of quantum mechanics.particle physics relativistic wave equationPaul Diracfree formelectromagnetic interactionsspin-½particlesparityelectronsquarksquantum mechanicsspecial relativityspecial relativityquantum mechanics

86. Dirac equation (continued) It accounted for the fine details of the hydrogen spectrum in a completely rigorous way. The equation also implied the existence of a new form of matter, antimatter, hitherto unsuspected and unobserved, and actually predated its experimental discovery. It also provided a theoretical justification for the introduction of several-component wave functions in Pauli's phenomenological theory of spin; the wave functions in the Dirac theory are vectors of four complex numbers (known as bispinors), two of which resemble the Pauli wavefunction in the non-relativistic limit, in contrast to the Schrödinger equation which described wave functions of only one complex value. Moreover, in the limit of zero mass, the Dirac equation reduces to the Weyl equation.hydrogen spectrumantimatterPauliphenomenologicalspincomplex numbersbispinorsSchrödinger equationWeyl equation

87. Dirac equation (continued) Although Dirac did not at first fully appreciate the importance of his results, the entailed explanation of spin as a consequence of the union of quantum mechanics and relativity—and the eventual discovery of the positron—represent one of the great triumphs of theoretical physics. This accomplishment has been described as fully on a par with the works of Newton, Maxwell, and Einstein before him. In the context of quantum field theory, the Dirac equation is reinterpreted to describe quantum fields corresponding to spin-½ particles.positrontheoretical physicsNewtonMaxwell Einsteinquantum field theory

88. Exercises

89. Exercises (continued) 56. An electron has n = 4, l = 2. What valued of m l are possible? 57. What are the energy and angular momentum of the electron in a hydrogen atom with n = 6, l = 4? 58. Which of the following electron configurations are possible and which are not (a) 1s 2 2s 2 2p 6 3s 3 ; (b) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 ; (c) 1s 2 2s 2 2p 6 2d 1 ? 59. Write the complete ground state configuration for lithium. 60. Estimate the wavelength for an n = 2 to n = 1 transition in molybdenum (Z = 42). What is the energy of such a photon?

90. Exercises (continued) 61. High energy photons are used to bombard an unknown material. The strongest peak is found for X-rays emitted with energy of 66 keV. Guess what the material is.

91. Molecules and Solids

92. Covalent bond A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding. For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full outer shell, corresponding to a stable electronic configuration.chemical bond electron pairsatoms Covalent bonding includes many kinds of interactions, including σ- bonding, π-bonding, metal-to-metal bonding, agostic interactions, and three-center two-electron bonds. The term covalent bond dates from 1939. The prefix co- means jointly, associated in action, partnered to a lesser degree, etc.; thus a "co-valent bond", in essence, means that the atoms share "valence", such as is discussed in valence bond theory.σ- bondingπ-bondingagostic interactions three-center two-electron bondsvalencevalence bond theory

93. Ionic bonding Ionic bonding is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions. These ions represent atoms that have lost one or more electrons (known as cations) and atoms that have gained one or more electrons (known as an anions). In the simplest case, the cation is a metal atom and the anion is a nonmetal atom, but these ions can be of a more complex naturechemical bondelectrostaticionselectronscationsanionsmetalnonmetal

94. van der Waals force In physical chemistry, the van der Waals force (or van der Waals' interaction), named after Dutch scientist Johannes Diderik van der Waals, is the sum of the attractive or repulsive forces between molecules (or between parts of the same molecule) other than those due to covalent bonds, or the electrostatic interaction of ions with one another, with neutral molecules, or with charged molecules.physical chemistry DutchscientistJohannes Diderik van der Waalsmolecules covalent bondselectrostatic interactionions

95. Metallic bonding Metallic bonding occurs as a result of electromagnetism and describes the electrostatic attractive force that occurs between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions. It may be described as the sharing of free electrons among a lattice of positively charged ions (cations). In a more quantum-mechanical view, the conduction electrons divide their density equally over all atoms that function as neutral (non- charged) entities. Metallic bonding accounts for many physical properties of metals, such as strength, ductility, thermal and electrical resistivity and conductivity, opacity, and luster.electromagnetismconduction electronsdelocalized electronslatticecationsquantum-mechanicalphysical propertiesstrengthductilitythermalelectrical resistivity and conductivityopacityluster Metallic bonding is not the only type of chemical bonding a metal can exhibit, even as a pure substance. For example, elemental gallium consists of covalently-bound pairs of atoms in both liquid and solid state—these pairs form a crystal lattice with metallic bonding between them.chemical bondinggalliumcrystal lattice

96. Conduction band The conduction band quantifies the range of energy required to free an electron from its bond to an atom. Once freed from this bond, the electron becomes a 'delocalized electron', moving freely within the atomic lattice of the material to which the atom belongs. Various materials may be classified by their band gap: this is defined as the difference between the valence and conduction bands.atomatomic latticeband gapvalence In insulators, the conduction band is much higher in energy than the valence band and it takes large energies to delocalize their valence electrons. Insulating materials have wide band gaps. In semiconductors, the band gap is small. This explains why it takes a little energy (in the form of heat or light) to make semiconductors' electrons delocalize and conduct electricity, hence the name, semiconductor. In metals, the Fermi level is inside at least one band. These Fermi-level-crossing bands may be called conduction band, valence band, or something else depending on circumstance. Electrons within the conduction band are mobile charge carriers in solids, responsible for conduction of electric currents in metals and other good electrical conductors.Fermi levelcharge carrierselectric currentselectrical conductors

97. Valence band In solids, the valence band is the highest range of electron energies in which electrons are normallysolids electronenergies The valence electrons are bound to individual atoms, as opposed to conduction electrons (found in conductors and semiconductors), which can move freely within the atomic lattice of the material. On a graph of the electronic band structure of a material, the valence band is located below the conduction band, separated from it in insulators and semiconductors by a band gap. In metals, the conduction band has no energy gap separating it from the valence band. present at absolute zero temperature.valence electronsatomsconduction electronsconductorssemiconductors atomic lattice electronic band structureconduction bandinsulatorsband gap metalsabsolute zero

98. Semiconductor A semiconductor material has an electrical conductivity value between a conductor, such as copper, and an insulator, such as glass. Semiconductors are the foundation of modern electronics. The modern understanding of the properties of a semiconductor relies on quantum physics to explain the movement of electrons and holes in a crystal lattice. An increased knowledge of semiconductor materials and fabrication processes has made possible continuing increases in the complexity and speed of microprocessors and memory devices.electrical conductivityconductorinsulatorelectronicsquantum physicselectronsholescrystal latticemicroprocessors The electrical conductivity of a semiconductor material increases with increasing temperature, which is behaviour opposite to that of a metal. Semiconductor devices can display a range of useful properties such as passing current more easily in one direction than the other, showing variable resistance, and sensitivity to light or heat. Because the electrical properties of a semiconductor material can be modified by controlled addition of impurities, or by the application of electrical fields or light, devices made from semiconductors can be used for amplification, switching, and energy conversion.electrical conductivitySemiconductor devicesresistance CurrentCurrent conduction in a semiconductor occurs through the movement of free electrons and "holes", collectively known as charge carriers. Adding impurity atoms to a semiconducting material, known as "doping", greatly increases the number of charge carriers within it. When a doped semiconductor contains mostly free holes it is called "p-type", and when it contains mostly free electrons it is known as "n-type". The semiconductor materials used in electronic devices are doped under precise conditions to control the location and concentration of p- and n-type dopants. A single semiconductor crystal can have many p- and n-type regions; the p–n junctions between these regions are responsible for the useful electronic behaviour.dopingp–n junctions Some of the properties of semiconductor materials were observed throughout the mid 19th and first decades of the 20th century. Development of quantum physics in turn allowed the development of the transistor in 1948. Although some pure elements and many compounds display semiconductor properties, silicon, germanium, and compounds of gallium are the most widely used in electronic devices.transistorsilicongermanium gallium

99. Doping (semiconductor) In semiconductor production, doping intentionally introduces impurities into an extremely pure (also referred to as intrinsic) semiconductor for the purpose of modulating its electrical properties. The impurities are dependent upon the type of semiconductor. Lightly and moderately doped semiconductors are referred to as extrinsic. A semiconductor doped to such high levels that it acts more like a conductor than a semiconductor is referred to as degenerate.semiconductorintrinsic extrinsicconductordegenerate In the context of phosphors and scintillators, doping is better known as activation.phosphorsscintillatorsactivation

100. Diode In electronics, a diode is a two-terminal electronic component with asymmetric conductance; it has low (ideally zero) resistance to current in one direction, and high (ideally infinite) resistance in the other. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. A vacuum tube diode has two electrodes, a plate (anode) and a heated cathode. Semiconductor diodes were the first semiconductor electronic devices. The discovery of crystals' rectifying abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor diodes, called cat's whisker diodes, developed around 1906, were made of mineral crystals such as galena. Today, most diodes are made of silicon, but other semiconductors such as selenium or germanium are sometimes used.electronicsterminalelectronic componentconductanceresistancecurrentinfinitecrystallinesemiconductorp–n junctionvacuum tubeelectrodesplateheated cathode semiconductor electronic devicescrystalsrectifyingFerdinand Brauncat's whisker diodesgalenasilicon seleniumgermanium

101. p–n junction A p–n junction is a boundary or interface between two types of semiconductor material, p-type and n-type, inside a single crystal of semiconductor. It is created by doping, for example by ion implantation, diffusion of dopants, or by epitaxy (growing a layer of crystal doped with one type of dopant on top of a layer of crystal doped with another type of dopant). If two separate pieces of material were used, this would introduce a grain boundary between the semiconductors that would severely inhibit its utility by scattering the electrons and holes.p-typen-type semiconductordopingion implantation diffusiondopantsepitaxy grain boundaryscatteringholes p–n junctions are elementary "building blocks" of most semiconductor electronic devices such as diodes, transistors, solar cells, LEDs, and integrated circuits; they are the active sites where the electronic action of the device takes place. For example, a common type of transistor, the bipolar junction transistor, consists of two p–n junctions in series, in the form n–p–n or p–n–p.semiconductor electronic devicesdiodestransistorssolar cellsLEDsintegrated circuitstransistorbipolar junction transistor The discovery of the p–n junction is usually attributed to American physicist Russell Ohl of Bell Laboratories. Russell OhlBell Laboratories A Schottky junction is a special case of a p–n junction, where metal serves the role of the p-type semiconductor.Schottky junction

102. Rectifier A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification. Physically, rectifiers take a number of forms, including vacuum tube diodes, mercury-arc valves, copper and selenium oxide rectifiers, semiconductor diodes, silicon-controlled rectifiers and other silicon-based semiconductor switches. Historically, even synchronous electromechanical switches and motors have been used. Early radio receivers, called crystal radios, used a "cat's whisker" of fine wire pressing on a crystal of galena (lead sulfide) to serve as a point- contact rectifier or "crystal detector".convertsalternating current direct currentvacuum tubediodes mercury-arc valves semiconductor diodessilicon-controlled rectifiers crystal radioscat's whiskergalena

103. Transistor A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.semiconductor deviceamplifyswitchelectronicelectrical powersemiconductor currentpoweramplifyintegrated circuits The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Following its development in 1947 by American physicists John Bardeen, Walter Brattain, and William Shockley, the transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things. The transistor is on the list of IEEE milestones in electronics, and the inventors were jointly awarded the 1956 Nobel Prize in Physics for their achievement.electronic devicesphysicistsJohn BardeenWalter BrattainWilliam ShockleyradioscalculatorscomputersIEEE milestonesNobel Prize in Physics

104. Exercises

105. Exercises (continued) 56. An electron has n = 4, l = 2. What valued of m l are possible? 57. What are the energy and angular momentum of the electron in a hydrogen atom with n = 6, l = 4? 58. Which of the following electron configurations are possible and which are not (a) 1s 2 2s 2 2p 6 3s 3 ; (b) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 ; (c) 1s 2 2s 2 2p 6 2d 1 ? 59. Write the complete ground state configuration for lithium. 60. Estimate the wavelength for an n = 2 to n = 1 transition in molybdenum (Z = 42). What is the energy of such a photon?

106. Exercises (continued) 61. High energy photons are used to bombard an unknown material. The strongest peak is found for X-rays emitted with energy of 66 keV. Guess what the material is.

107. Nuclear Physics and Radioactivity

108. Structure and properties of the nucleolus

109. Proton

110. Neutron

111. Atomic mass number

112. Isotope

113. Abandancy

114. Q = M P c 2 – (M D + m α )c 2 (30-2)

116. n → p + e - + a neutrino

117. Exercises