Abstract

Laser induced fluorescence and dispersed emission spectra of C₆F₆Ar_n (n = 1–10) clusters have been studied in a supersonic freejet expansion. By controlling the expansion conditions, we can approximately mass select the clusters and selectively pump the ${\text{C}}_6{\text{F}}_6^{+}{\text{Ar}}_n$ from the ground electronic state to different vibrational modes of the excited electronic state. We observe that the wavelength resolved emission consists of a broad (about 1300 cm^-1, FWHM), Stokes shifted spectrum that is independent of vibrational excitation and indicative of condensed phase emission. This is in contrast to the LIF spectrum, which yields much narrower linewidths. The emission and excitation spectra show an increasing red shift with larger cluster size that saturates at high pressure. A model is proposed for explaining all the above phenomena. A similar experiment is also being performed with C₆F₆He_n clusters.

© 1992 Optical Society of America