EXCITATION PROFILE OF COHERENT ANTI-STOKES-RAMAN SCATTERING FROM THE MNO4- ION DOPED IN A KCLO4 CRYSTAL AT LOW-TEMPERATURE

We have performed polarized resonance coherent anti-Stokes Raman exper iments on the permanganate ion doped in potassium perchlorate single c rystals at temperature T = 15 K. At this temperature the m (C(S)) site splitting of the excited degenerate 1T2-electronic level of the perma nganate ion and the vibronic structure are well resolved. We report on the A'-nu1 coherent anti-Stokes Raman excitation profile which shows a strong dependence on the frequency of the pump laser. The simulation of the experimental results is performed by using the transform theor y, which enables one to calculate the resonance Raman excitation profi le solely from the measured absorption spectrum. According to the well known relation between the third-order nonlinear susceptibility and t he Raman polarizability the coherent anti-Stokes excitation profile is given by a simple product of two Raman excitation profiles which are shifted relative to each other. The linear and the quadratic electron- phonon coupling as well as the influence of non-Condon terms were take n into account. Since the transform theory is mode selective in case t here are no mode mixing effects the results derived from the descripti on of the Raman excitation profiles and the coherent anti-Stokes excit ation profiles are more definite. For this purpose one only needs the model parameters of the mode of interest. The simulation of the A'-nu1 coherent anti-Stokes profile shows that a small amount of non-Condon coupling yields to a better agreement with the experiment.