# SPECTROSCOPIC STUDIES OF THE $\tilde{B}^{2} A''-\tilde{X}^{2}A'$ SYSTEM OF THE JET-COOLED VINOXY $RADICAL^{*}$

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 Title: SPECTROSCOPIC STUDIES OF THE $\tilde{B}^{2} A''-\tilde{X}^{2}A'$ SYSTEM OF THE JET-COOLED VINOXY $RADICAL^{*}$ Creators: Brock, L. R.; Rohlfing, Eric A. Issue Date: 1997 Publisher: Ohio State University Abstract: Jet-cooled vinoxy radicals $(CH_{2}CHO)$ are produced in the initial portion of a helium free-jet expansion by photolysis of ethyl vinyl ether using the focused output from an ArF excimer laser (193 nm). Vibrationally and rotationally resolved electronic spectra of the $\tilde{B}^{2} A^{\prime\prime}-\tilde{X}^{2} A^{\prime\prime}$ transition of vinoxy are recorded using a variety of spectroscopic techniques. Both laser-induced fluorescence (LIF) and two-color resonant four-wave mixing (TC-RFWM) are employed to collect vibronically resolved excitation spectra. Rotationally resolved LIF spectra of nine bands are recorded to help conform our vibrational assignments using a single-longitudinal-mode optical parametric oscillator/amplifier system. The band origins, rotational constants and inertial defects are determined. In addition, the fluorescence lifetimes of 19 $\tilde{B}$-state levels are measured, and dispersed fluorescence (DF) spectra are collected from 7 of the most strongly fluorescing levels in the $\tilde{B}$-state. In total, we assign 54 levels in the $\tilde{B}$-state and 57 levels in the $\tilde{X}$-state, including 6 $a^{\prime}$ fundamentals and all three $a^{\prime\prime}$ overtones in both states. Analysis of the fluorescence lifetime date, and comparison of the LIF and TC-RFWM spectra reveal a sudden increase in the predissociation rate at $= 1190\;cm^{-1}$ above the origin. This phenomena, which is likely due to a vibronic interaction with the $\tilde{A}^{2}A^{\prime}$ of $\tilde{C}^{2}A^{\prime}$ states, will be discussed. Description: $^{*}$This work supported by the U. S. Department. of Energy, Office of Basic Energy Sciences, Chemical Sciences Division. Author Institution: Combustion Research Facility, Sandia National Laboratories URI: http://hdl.handle.net/1811/14056 Other Identifiers: 1997-TD-06