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Molekulaspektroszkopia segédábrák Az ábrák több, részben szerzői jogokkal védett műből, oktatási célra lettek kivéve. Csak az intranetre tehetők, továbbmásolásuk,

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Presentation on theme: "Molekulaspektroszkopia segédábrák Az ábrák több, részben szerzői jogokkal védett műből, oktatási célra lettek kivéve. Csak az intranetre tehetők, továbbmásolásuk,"— Presentation transcript:

1 Molekulaspektroszkopia segédábrák Az ábrák több, részben szerzői jogokkal védett műből, oktatási célra lettek kivéve. Csak az intranetre tehetők, továbbmásolásuk, terjesztésük nem megengedett. Az ábrák csak illusztrációs célokat szolgálnak. Mivel többnyire más szerzők műveiből származnak, olyan jelölések vagy állítások is előfordulhatnak bennük, amelyekkel a tantárgy oktatói nem teljesen értenek egyet.

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8 "Heat Infrared radiation is popularly known as "heat" or sometimes "heat radiation," since many people attribute all radiant heating to infrared light, but this is a widespread misconception. Light and electromagnetic waves of any frequency will heat surfaces which absorb them. IR light from the sun only accounts for 50% of the heating of the Earth, the rest being caused by visible light. Green (or even UV) lasers can char paper and incandescently hot objects put out visible radiation. However, it is true that objects at room temperature will emit radiation mostly concentrated in the 8-12 micron band (see black body).heattemperatureemitradiationblack body

9 Die Wellenlänge der Ultraviolettstrahlung reicht von 1 nm bis 380 nm.nm Die Frequenz der Ultraviolettstrahlung reicht also von 789 THz (380 nm) bis 300 PHz (1 nm).FrequenzTHzPHz Die Energie eines einzelnen Lichtquants liegt im Bereich von ca. 3,3 eV (380 nm) bis ca eV (1 nm).LichtquantseV 1 eV = 1, (63) · JJ Ein typisches Molekül in der Atmosphäre hat eine Bewegungsenergie (thermische Energie) von etwa 0,03 eV. Die Photonen von sichtbarem Licht (rot) haben eine Energie von etwa 2 eV.thermische EnergiePhotonenLicht Boltzman-Konstante 1,38 · J K -1 8,62· eV K -1JKeVK Plancksches Wirkungsquantum h 4,14 · eV seVs Die ultraviolette Strahlung wurde 1802 von Johann Wilhelm Ritter entdeckt.1802Johann Wilhelm Ritter

10 Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays. It can be subdivided intoelectromagnetic radiationwavelengthX-rays near UV (380–200 nm wavelength; abbrev. NUV), far or vacuum UV (200–10 nm; abbrev. FUV or VUV), andnm extreme UV (1–31 nm; abbrev. EUV or XUV). When considering the effect of UV radiation on human health and the environment, the range of UV wavelengths is often subdivided into UVA (400– 315 nm), also called Long Wave or "blacklight"; UVB (315–280 nm), also called Medium Wave; and UVC (< 280 nm), also called Short Wave or "germicidal".

11 Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths while Silica or quartz glass, depending on quality, can be transparent even to vacuum UV wavelengths. Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm[1][2][3].glassSilica or quartz glass[1][2][3] The onset of vacuum UV, 200 nm, is defined by the fact that ordinary air is opaque below this wavelength. This opacity is due to the strong absorption of light of these wavelengths by oxygen in the air. Pure nitrogen (less than about 10 ppm oxygen) is transparent to wavelengths in the range of about 150–200 nm. This has wide practical significance now that semiconductor manufacturing processes are using wavelengths shorter than 200 nm.

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14 Copyrighted, by Nick Strobel

15 Copyrighted, by Nick Strobel

16 Properties of Electromagnetic Radiation Fig. 19-1, pg. 511 Plane-polarized electromagnetic radiation of wavelength, propagating along the x axis. The electric field of the plane-polarized light is confined to a single plane. Ordinary, unpolarized light has electric field components in all planes."

17 Regions of Electromagnetic Spectrum

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20 Attenuation of Light

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27 Grating vs. Prism

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30 Beer's Law Instrumental response G = KP + K' 100% adjust, incident radiation G o = 100 = KP o K = 100/P o

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32 Double Beam Spectrometer

33 HP 8452a

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36 Components of Optical Instruments Fig. 7-2, pg. 145 (a) Construction materials

37 Components of Optical Instruments Fig. 7-2, pg. 145 (b) wavelength selectors for spectroscopic instruments."

38 Components of Optical Instruments Fig. 7-3, pg. 146 (a) Sources."

39 Components of Optical Instruments Fig. 7-3, pg. 146 (b) detectors for spectroscopic instruments."

40 Properties of Electromagnetic Radiation Fig. 6-2, pg. 118 "Effect of change of medium on a monochromatic beam of radiation."

41 Properties of Electromagnetic Radiation Fig. 6-3, pg. 119 "Regions of the electromagnetic spectrum"

42 Absorption of Radiation Fig. 6-19, pg.134 "Some typical ultraviolet absorption spectra."

43 Monochromator Slits Construction of slits

44 Total Absorption A T = A 1 + A 2 + A 3 + An A T = 1 bc bc 2 + bc 3 + n bc n

45 Analysis of Mixtures of Absorbing Substances Selection of Wavelength Fig , pg. 345 "Absorption spectrum of a two- component mixture."

46 Real Deviations non-monochromatic radiation Fig. 13-4, pg. 305 "Deviations Beer's Law with polychromatic light. Here, two wavelenghts or radiation 1 and 2 have been assumed for which the absorber has the indicated molar absorptivities."

47 Real Deviations Fig. 13-5, pg. 306 "The effect of polychromatic radiation upon the Beer's law relationship. Band A shows little deviation, because does not change greatly throughout the band. Band B shows marked deviations because undergoes significant changes in this region."

48 Real Deviations stray light Fig. 13-6, pg. 307 "Apparent deviation from Beer's law brought about by various amounts of stray radiation."

49 Single Beam vs. Double Beam Fig , pg. 315 "Instrument designs for photometers and spectrophotometers: (a) single-beam design (b) dual channel design with beams separated in space but simultaneous in time (c) double-beam design in which beams alternate between two channels."

50 Types of Transitions Fig. 14-1, pg. 331 "Electron distribution in sigma and pi molecular orbitals."

51 Types of Transitions Fig. 14-2, pg. 331 "Types of molecular orbitals in formaldehyde."

52 Absorbing Species Containing,, and n Electrons Fig. 14-3, pg. 331 "Electonic molecular energy levels." n Antibonding Nonbonding Bonding n n

53 UV Spectra Fig. 14-4, pg. 334 Ultraviolet spectra for typical organic compounds.

54 Visible Spectra Fig. 14-5, pg 334 Ultraviolet absorption spectra for 1,2,4,5- tetrazine (a.) in the vapor phase, (b.) in hexane solution, and (c.) in aqueous solution.

55 Types of Transitions Table 14-2, pg. 333 "Aborption Characteristics of Some Common Chromophores. "

56 Types of Transitions Table 14-3, pg. 355 "Effect of Multichromophores on Absorption."

57 Interferogram vs. Spectrum

58 Qualitative Analysis Fig. 17-4, pg. 408 Group frequency and fingerprint regions of the mid-infrared spectrum.

59 Qualitative Analysis Fig. 17-4, pg. 408 Group frequency and fingerprint regions of the mid-infrared spectrum.

60 Qualitative Analysis Fig. 17-4, pg. 408 Group frequency and fingerprint regions of the mid-infrared spectrum.

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62 Vibration Modes Fig. 16-2, pg. 383 Types of molecular vibrations. Note: + indicates motion from the page toward the reader; - indicates motion away from the reader.

63 Potential Energy Diagram Fig. 16-3, pg. 384 Potential energy diagrams. Curve 1, harmonic oscillator. Curve 2, anharmonic oscillator.

64 Infrared Sources Most Common IR Sources Nernst glower –cylinder of rare-earth oxides glowbar –silicon carbide rod –50mm long by 5mm diameter incandescent wire –nichrome wire

65 Infrared Detectors thermocouples pyroelectrics

66 Table 17-1, pg. 405 Major Applications of Infrared Spectrometry

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70 Sample Techniques film smear sample cell gas cell KBr pellet Nujol mull internal reflectance apparatus

71 Deuterium lamps are gas discharge lamps filled with Deuterium at carefully controlled pressures. They provide a line free continuous UV spectrum from 180nm to 370nm, Tungsten Halogen lamps (TH) are compact gas filled filament lamps that provide a continuum output from 350nm to 1000nm.

72 Emission spectrum of an ultraviolet deuterium arc lampspectrum


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