VIBRATIONAL OVERTONES IN THE ELECTRONIC GROUND-STATE OF THE BENZENE-AR COMPLEX - A COMBINED EXPERIMENTAL AND THEORETICAL-ANALYSIS

Using the recently developed method of coherent ion dip spectroscopy ( CIS), we were able to measure rotationally resolved spectra of high ly ing overtones of the intermolecular van der Waals vibrations of the be nzene-Ar complex. Optimized pulse sequences for the CIS experiment wer e obtained by numerical calculations of the population dynamics in the coherently excited few-level system. Due to the high resolution achie ved in this experiment, the small isotope shifts upon deuteration of t he benzene molecule could be measured and compared with the simple cla ssical harmonic oscillator and with anharmonic three-dimensional quant um calculations. By comparing the latter calculations with the results of the CIS experiments, we tested the quality of several benzene-Ar i nteraction potentials. (C) 1998 American Institute of Physics. [S0021- 9606(98)01920-5]