The coupling between electrons and highly vibrationally excited molecules in optically pumped plasmas

Summary form only given. The paper addresses ionization in collisions of highly excited carbon monoxide molecules (v=25-40), as well as energy transfer from the vibrational mode of CO to free electrons. Carbon monoxide in a CO-Ar-He mixture is vibrationally excited by resonance absorption of the CO laser radiation in an optical absorption cell. The pressure in the cell is P=100 Torr. The laser has a total power output of 10 W, with about 0.25 W on a 1/spl rarr/0 band and is repetitively pulsed, which allows studying time-dependent excitation. Only the low vibrational levels of CO (v<12) are populated by a laser. The high vibrational levels (up to v=40) are populated by vibration-vibration (V-V) pumping. Time-dependent first overtone CO infrared spectra are taken by a step-scan Fourier transform infrared spectrometer (FTIR), with the time resolution of 50 /spl mu/sec and spectral resolution of 0.25 cm/sup -1/. From these spectra both rotational temperature of the mixture (T=400-700 K) and time-dependent absolute populations of individual vibrational levels of CO are inferred.