Structure Determination Using Spectroscopy Need methods to distinguish between possible structures A nondestructive way is to use absorption spectroscopy In a simplified picture: Beam splitter Monochromatic sample light source detector 不N blank The ability of the sample to absorb incident radiation is measured by the difference in absorbance at the detector versus the blank
Structure Determination Using Spectroscopy Need methods to distinguish between possible structures A nondestructive way is to use absorption spectroscopy In a simplified picture: The ability of the sample to absorb incident radiation is measured by the difference in absorbance at the detector versus the blank Monochromatic light source sample blank detector Beam splitter
Electromagnetic Spectrum All light travels at a constant speed The difference is the wavelength of the light (which also determines the energy of the light) E=hv=(hc)/入 NMR IR UV-vis uildings insects and protozoa molecules atoms tocic gbaea radio microwave (sub)mm infrared visible ultraviolet x-ray :gamma-ray 10m 10cm 0.3mm 780mm380nm 10mm.01nm 0.000001nm wavelength AAAM frequency(Hz) 107 109 10 1012101 1051016 1019 1020 1027 energy(eV） 108 105 103 1021 10 100 105 109109 102
Electromagnetic Spectrum All light travels at a constant speed The difference is the wavelength of the light (which also determines the energy of the light) E = hν = (hc) / λ NMR IR UV-vis