Dynamics of vibrationally excited van der Waals complex: Stimulatedemissionpumping laserinduced fluorescence spectroscopy of the anisoleAr complex J. Chem. Phys. 98, 6958 (1993); 10.1063/1.464737 Fluorescence excitation spectrum of the Si-Ar van der Waals complex J. Chem. Phys. 92, 2828 (1990); 10.1063/1.457929 Stimulated emission spectroscopy of van der Waals vibrational levels of glyoxal(X1Ag)Ar m n complexes with progressions of the associated van der Waals vibrational levels. Of the six complexes, three are isomers of
Stimulated emission spectroscopy was used to study the electronic ground state vibration–rotation levels of van der Waals complexes generated in a supersonic beam. This technique can be used to study all the vibrational levels with nonvanishing Franck–Condon factors from the electronic excited states with 0.04 cm−1 resolution. Five van der Waals vibrational levels in the X̃ state were directly observed in the stimulated emission spectra and were assigned to the fundamental and first overtone levels of the two Ar⋅glyoxal bending modes and the stretching fundamental level. In addition, the rotational constants and the structure were determined for both the à and X̃ state complex, together with the vibrational term values and the widths of single rotational levels of the three glyoxal vibrations in the glyoxal⋅Ar complex, the C–C stretch v4=1, the CH wag v8=1 and the OCC bend v5=1 level.
In combination with supersonic cooling, stimulated emission pumping (SEP) can be used to obtain vibrational spectra of medium-size molecules in their electronic ground state with single rotational level selectivity. The greatly reduced rotational congestion in the spectra of 0.04 cm−1 resolution makes the vibration–rotation assignment straightforward. Two vibrational levels, C–C stretching v4=1 with vibrational term values determined at 1065.80(1) cm−1 and CH wagging v8=1 at 1048.07(1) cm−1, of glyoxal were studied. These vibrational levels are symmetry forbidden in the IR spectroscopy, but can be detected by SEP. Their rotational constants are determined from primarily the low J, K levels, as A=1.9394(25), B=0.1594(25), and C=0.1426(25) cm−1 for 41 and A=1.7335(14), B=0.1594(10), and C=0.1464(8) cm−1 for 81. The A constants and the symmetries indicate that the two vibrational levels are strongly coupled to each other through the a-axis rotation. A deperturbation analysis yielded the A constants as 1.8414(126) for 41 and 1.8317(127) for 81, as well as the Coriolis coupling constant ζa48 =0.3642(226). These, and other previous observations, indicate that Coriolis interactions are important in promoting intramolecular vibrational relaxation in the glyoxal molecule.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.