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.

UV‐excited continuum resonance Raman scattering from 35Cl2

“…2 we used the same potential functions as given in Table 1 in Ref. 6. Both theoretical spectra reproduce well the experimentally observed spectra, particularly the increase in hot band intensity for lower wavelength excitation.…”

“…On the other hand, Strempel and Kiefer6 observed a decrease in the hot band intensities with increasing laser energy for excitation wavelengths from 363.8 to 333.6 nm (see, for example, the spectra shown in Figs 2 and 3 in Ref. 6 for Au = 2 and 4 transitions, respectively). In order to elucidate this seemingly conflicting behaviour of the hot band intensities, we plotted the excitation profiles for various vibrational transitions (Au = 2, 3 and 4) and their hot bands in Fig.…”

“…The present observations strongly support those made earlier with longer excitation wavelengths. 6 We have recently summarized aspects of the time evolution of resonance Raman scattering, particularly the scattering via continuous states." Useful quantities in this respect are the time-dependent Franck-Condon overlap functions and the modulus of their integrals as a function of time.…”

Mass-resolved multiphoton ionization spectroscopy of jet-cooled Cl2. I. Bound-free-bound spectroscopy

“…19 The X( 1 ⌺ g ϩ ), B( 3 ⌸ 0u ϩ ), and C( 1 ⌸ 1u ) states are generated from data given in the literature. [20][21][22] The repulsive 3 ⌸ g and 1 ⌸ g valence state potentials are generated from a series of knot points placed so that they cross the 4s Rydberg states in positions estimated from the current experimental results and have the correct dissociation limits. The relative positions of the 4s Rydberg states and the 1,3 ⌸ g repulsive valence states shown in Fig.…”

Continuum resonance Raman scattering in isotopically pure127I35Cl

“…As has been shown on various examples earlier, continuum resonance Raman spectra are extremely sensitive to changes in the excited state potential functions and therefore represent valuable experimental data for the precise determination of these states. Particularly work has recently been carried out in this respect for the isotopically pure bromine [18], iodine [19] and chlorine [20] molecules.…”