Refractive Index Changes Temperature and Density Effects

The component p (l) is dne to the electrostiictive effect (the movement of molecules under intense electric field) it is proportional to y and is characterized by the Brillouin relaxation constant and frequency Q. From Equations (9.9) and (9.19) one can see that this component gives rise to a propagating wave. On the other hand, the component p (f) is due to the thermoelastic contribution (proportional to p ) and is characterized by the thermal decay constant it is nonprop-agative. 

More detailed solutions of the coupled density and temperature equations [Eqs. (9.4) and (9.5)] may be found in the woik by Batra et al. The preceding simple example, however, will suffice to illustrate the basic processes following photoabsorption and their time evolution characteristics. 

REFRACTIVE INDEX CHANGES TEMPERATURE AND DENSITY EFFECTS 

Because of these temperature and density changes, there are corresponding refractive index changes given, respectively, by 

The thermal index component dn/dT arises from two effects. One is the spectral shift as a result of the rise in the temperature of the molecule. This effect occurs within the thermalizationtime x (i.e., in the picosecond time scale), and its contribution is usually quite small for the ordered as well as the liquid phases. 

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