Band Broadening and Conformational Flexibility

The experimental spectroscopic facts which need to be accounted for in a comprehensive way in relation to order-disorder are the following (we report here the most striking manifestations, recorded in various ways, for oligo and polymethylene systems)  

When n-alkanes are inserted as clathrates in urea channels, the width of d is 

This interpretation may be only partial since Snyder has shown that band broadening of d and S modes is certainly observed also for hexadecane in urea clathrates where the molecule is believed to be (on average) in the rraH.y-planar 

A full discussion of the theory and experiments on band-broadening effects in n-alkanes is reported in [137]. We wish to outline here a few basic concepts which, in a first approximation, are the tool to be used in the understanding of the complex dynamics in conformationally flexible systems. 

Raman scattering provides a nice way to gather information on these processes. For liquid samples, it is possible to separate experimentally the isotiopic spectrum (ISOT) from the anisotropic one (ANIS), namely 

---