Difference-frequency laser spectroscopy of gas phase C2D in the 2800 cm−1 region

Abstract

The gas phase C2D absorption spectrum has been studied in the 2800 cm−1 region using a high resolution difference-frequency laser spectrometer. The C2D molecules were produced in a hollow cathode discharge in a mixture of C2H2 or C2D2 (∼20 mTorr) and D2 (∼400 mTorr). Two bands were identified and rotationally analyzed. One band at 2796 cm−1 was found to be a 2Π–2Σ+ transition with the lower state being the ground state. The upper level of this band is assigned to the (110) state in the ground electronic state, X̃ 2Σ+. The other band at 2851 cm−1 is a 2Σ+–2Σ+ transition from the (001) state in X̃ 2Σ+ to a vibronic 2Σ+ state which was found to be perturbed. Accurate molecular constants for the upper levels involved were determined from least-squares fit. These constants as well as the observed transition frequencies are reported.