Polarized and depolarized Raman scattering of 35Cl2 with excitation from the visible to the ultraviolet region

Abstract

We have recorded high-resolution polarized and depolarized Raman spectra of isotopically pure 35Cl2 using the argon ion laser lines 501.7, 496.5, 488.0, 476.5, 457.9, 363.8, 351.1, and 333.6 nm and the krypton ion laser line 413.1 nm. Overtone progressions can be observed for 413.1 nm and UV excitation. The spectral band shapes of the overtones show a systematic variation with excitation frequency. The relative intensities of the overtone bands have been calculated with second order perturbation theory. The spectral feature of the overtones can be explained by resonance Raman scattering via the repulsive 1Π1u state. The 1Π1u potential was determined with a high accuracy. This is possible because the Raman band intensities are very sensitive to the location of the potential curves of the involved excited scattering states. The spectral feature of the fundamental band excited in the UV region can be explained assuming a destructive interference effect between resonant and nonresonant Raman scattering resulting from adjacent highly lying states. This effect can be monitored via the depolarization ratio of the fundamental transitions, the change in relative intensities between the different Q branches of the fundamental bands and comparison of the observed and calculated overall band intensities of the fundamental and overtone bands excited with different laser lines.