MOLECULAR RELAXATION PROCESSES OF 2-BROMOPROPANE IN SOLUTIONS FROM IRNU(C-BR) BAND SHAPE-ANALYSIS

The infrared (C-Br) stretching band profile of 2-bromopropane in pure liquid and in solution was studied. The frequency shifts, described by the Buckingham equation, account for the influence of the polarity an d polarizability of the solvents. To evaluate the importance of the la st term in the Buckingham equation, which describes the mutual influen ce of these two effects, a linear multidimensional regression analysis was done. The correlation factor increased when the cross term was co nsidered. The concentration dependence of the FWHH (full width at half height) can be related to the vibrational relaxation processes, among them vibrational dephasing being the most important. More information about mechanisms responsible for the vibrational bandshape can be obt ained from the correlation function Phi(t). As a result of modelling t he experimental CF with Kubo-Rothschild's model, the modulation of the vibrational frequencies is found to be of intermediate type. (C) 1998 Elsevier Science B.V. All rights reserved.