Fluorimetry and Phosphorimetry:
You have studied about UV-VIS, IR and Raman spectrometric methods. These techniques were based on the absorption of radiation in UV-visible and IR regions and on the scattering of radiation. You have learnt in which the absorption of electromagnetic radiation in the UV-visible region leads to an electronic excitation of the absorbing species while in case of IR radiations the transitions occur in the vibrational energy levels. In Raman spectrometry, instead, we measure the scattered radiation arising as a consequence of elastic and inelastic collisions of radiation along with matter.
Here, you would learn about two more molecular spectroscopic techniques, namely phosphorescence and fluorescence. These are based on the phenomenon of emission of radiation through electronically excited species and are collectively termed as photoluminescence methods. We shall starts along with the understanding of the origin of fluorescence and phosphorescence spectra within terms of the radiative relaxation processes related with electronically excited species. It will be followed through the study of the relationship of fluorescence and phosphorescence with chemical structure and the dependence of the spectra on the environment of the species. A brief account of the necessary components and the principles of the spectrofluorimeters are also given. Thereafter, a few simple applications based on measurement of fluorescence and phosphorescence spectra have been discussed in brief. Further, we shall take up the applications of fluorescence and phosphorescence measurements in detail.
Objectives
After studying this unit, you should be able to:
- Elaborates the origin of fluorescence and phosphorescence spectra,
- Differentiate among fluorescence and phosphorescence,
- Describes and differentiate among radiative and nonradiative relaxation mechanisms,
- Associate fluorescence and phosphorescence emission to the chemical structure,
- Compare phosphorescence and fluorescence measurements along with absorption measurements,
- Elaborates fluorescence quenching and state reasons for the similar,
- Define briefly the elements of fluorescence and phosphorescence instruments,