1. Wavelike Properties of Electromagnetic Radiation 1.Wave parameters 2.Refraction a.Index of refraction Snell’s Law b. Prism monochrometers 3.Diffraction a. slit width 4. Reflection 5. Scattering

2. Wave parameters Wavelength depends upon the medium the electromagnetic radiation is traveling in Frequency is a set quantity dependent on radiation source c = only strictly true in a vacuum

3. Refraction: deflection of propagating waves at boundary between 2 media of 2 different refractive indexes As light moves from high velocity medium to low velocity medium, light moves toward normal

4. A beam of light at a wavelength of 550nm in air is incident on a slab of transparent material. It has an angle of incidence of 40 o with the normal and the refracted beam makes an angle of 26 o with the normal. Find n for the material. What is the wavelength of light in the material?

5. Refraction is most common way wavelike properties of light manifest themselves Instruments benefit from this in: monochrometer design What is a monochrometer? Something which selects for just one wavelength of light.

6. Prism

7. Diffraction Visual

8. Reflection Calculate what the % transmittance of light going perpendicular through regular plate glass (n = 1.50) will be.

9. Ways to reduce reflected losses 1) Coating with a low reflectance material 2) Cementing optical elements that are in contact with a material of similar refractive index (rather than leaving air gaps in between).

10. Reflectance as a function of angle of incidence

11. Scattering Particles will scatter light if: 1) The particles have dimensions on the order of magnitude or smaller than incident wavelengths 2) Are randomly distributed in a medium of refractive index different than their own

12. Structures Producing Scattering Wavelength (  m) Spectral Region Max. Particle Size (  m) Type of Aggregate 10IR15Large colloidal particles 0.5Visible0.75 Colloidal particles, macromolecu les 0.001X ray0.002 Small molecules, atoms

13. A Chemical Sunset Demo 1.How is this reaction similar to a natural sunset? 2.What causes the different colors to be produced? 3.What other compounds might produce a similar reaction? 4.What is a colloidal suspension? A Chemical Sunset Demo

14. What color light will be scattered the most? Why is the sky blue? Some forms of spectroscopy rely upon scattering like Raman spectroscopy Why should you not touch cuvettes?