# LASER SPECTROSCOPY OF GAS PHASE $C_{2}D$ IN THE 2800 $cm^{-1}$ REGION

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 Title: LASER SPECTROSCOPY OF GAS PHASE $C_{2}D$ IN THE 2800 $cm^{-1}$ REGION Creators: Yan, W.- B.; Warner, H. E. Issue Date: 1990 Publisher: Ohio State University Abstract: The ethynyl radical, $C_{2}H$, is an important reaction intermediate in soot formation and is also widespread in interstellar space. Even though much work has been done on this molecule both in the solid matrix and in the gas phase, there is still controversy about the origin of the low-lying $^{2}\Pi ---^{2}\Sigma$ electronic transition, especially the frequency of the C---H stretch fundamental. We have recently studied the gas phase $C_{2}D$ absorption spectrum in the C---D stretch region ($\sim 2800 cm^{-1})$ using a high resolution difference-frequency laser spectrometer. The $C_{2}D$ molecules were produced in a hollow cathode discharge in a mixture of $C_{2}H_{2} (\sim 20$ mTorr) and $D_{2} (\sim 400$ mTorr). Measurements were carried out using discharge modulation at 2 kHz with a current of about 500 mA. Total laser pathlength was 36 m in a White cell arrangement. Two bands were identified: one with a symmetry of $^{2}\Sigma --- ^{2}\Sigma$ and the other $2\Pi --- ^{2}\Sigma$. The lower state of the $^{2}\Sigma --- ^{2}\Sigma$ transition is the (0 0 1) level of the $C_{2}D$ ground electronic state. The analysis of these bands will be presented. Description: Author Institution: Herzberg Institute of Astrophysics, National Research Council, Ottawa URI: http://hdl.handle.net/1811/18259 Other Identifiers: 1990-TB-4