CHEM 222 Chapter Notes - Chapter 20: Molar Attenuation Coefficient, Transition Metal, Molecular Electronic Transition
6 Apr 2016
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Electronic spectroscopy- is the study of transitions of electrons between energy levels. Colours arise from the selective absorption of light in the visible region of the spectrum. A uv visible spectrophotometer monitors the transmission of radiation through a sample (a compound dissolved in solution) and the solvent containing no sample. A= l c c= concentration (mol/l or mol/dm3) l=path length (cm) =molar extinction coefficient (molar absorbtivity) l/(mol cm) or dm3/(mol cm) Each maximum in the electronic spectrum is described by max & max. The y-axis can either be absorbance (a) or extinction coefficient ( ). The energy/wavelength of light absorbed corresponds to the energy required to promote electrons from filled (or partially filled) orbitals to empty (or partially empty) orbitals. This process is known as an electronic transition. The energy difference between the two orbitals corresponds to the energy of the electronic transition.
