Thermal effects in resonance Raman scattering

We have already argued that the phenomena of Raman scattering and fluorescence cannot be distinguished from each other unless the system interacts with its thermal environment. Next we extend the model discussed in Section 18.3 to explicitly include thermal relaxation effects. Our model now consists of four levels The incoming state zrt) = 11, vi, ki) with energy fCin = -F ha i mi = c ki  

In the two-configuration model (Eqs (18.52)) of inhomogeneous broadening a natural choice is to take ria = — i ll-, where z a is of the order of the inhomogeneous width. 

In these equations ,7= z- Ej. The terms with white as well as light-grey backgrounds arise from — i H,d with H given by (18.57). The tenns with dark-grey backgrounds that describe relaxation processes were added phenomenologically as follows  

Thermal transitions (population relaxation) between levels s andp is accounted for by the rates ksp = ks- p and, 5 = that connect between 

The molecule in the excited electronic state (levels p and s) can undergo nonthermal relaxation processes, for example, dissociation, ionization, and radiative damping. These processes are irreversible because their products are removed from the system, and they are accounted for by the damping rates Tj and Tp in Eqs (18.58b) and (18.58c), respectively. 

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Shreve A P and Mathies R A 1995 Thermal effects in resonance Raman-scattering—analysis of the Raman intensities of rhodopsin and of the time-resolved Raman-scattering of bacteriorhodopsin J. Phys. Chem. 99 7285-99... 

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