# ROVIBRATIONAL LEVEL STRUCTURE OF ACETYLENE BY STIMULATED EMISSION PUMPING: CORIOLIS COUPLING BETWEEN $\nu_{2} + 4\nu_{4}$ AND $7\nu_{4}$

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 Title: ROVIBRATIONAL LEVEL STRUCTURE OF ACETYLENE BY STIMULATED EMISSION PUMPING: CORIOLIS COUPLING BETWEEN $\nu_{2} + 4\nu_{4}$ AND $7\nu_{4}$ Creators: Moss, David B.; Duan, Richard; Jacobson, Matthew P.; O'Brien, Jonathan P.; Field, R. W. Issue Date: 1998 Publisher: Ohio State University Abstract: Stimulated emission (pumping (SEP) spectroscopy has been used to investigate the rovibrational level structure of $S_{0}$ acetylene with $0.1 cm^{-1}$ resolution at a vibrational energy of approximately $4400 cm^{-1}$. Both the e and f parity levels of the expected zero-order bright state $\nu_{2} + 4\nu_{4} (\ell = 0.2)$ are observed to be doubled by a rotationally inhomogeneous perturbation. SEP spectra obtained using $S_{1}$ intermediate levels with $K = 1$ vs. $K = 0$ reveal complementary intensity patterns, indicating that the perturbation follows a section rule for vibrational angular momentum of $\Delta \ell = odd$. The perturbation is assigned to a Coriolis interaction between $\nu_{2} + 4\nu_{4}$ and the pure bending dark state $7\nu_{4}$. Zero-order vibrational energies and B values, as well as the Cariolis coupling coefficient, are derived from a fit of greater than 60 rovibrational levels of both parties with $J = 1$ to 13. Parameters derived from the fit are compared with predictions based on previous infrared and dispersed fluorescence studies. Axis-switching effects are also found to contribute significantly to the observed intensities. Description: Author Institution: Division of Science and Mathematics, College of General Studies, Boston University; Department of Chemistry, Massachusetts Institute of Technology URI: http://hdl.handle.net/1811/18922 Other Identifiers: 1998-RF-09