Abstract

The number densities in the low-lying vibrational states of N₂ in the electronic ground state of flowing active nitrogen have been measared by using coherent anti-Stokes Raman scattering (CARS) spectroscopy at 17 Torr as a function of the residence time of the gas exposed to a specimen solid surface. The active nitrogen was generated in the positive column of a water-cooled dc discharge. Vibrational deactivation coefficients were determined for several materials, including Pyrex, aluminum, and stainless steel. These studies used a narrow-line (0.1-cm⁻¹) tuneable dye (probe) laser and a single-mode (0.006-cm⁻¹) pulsed (7-ns) doubled Nd:YAG pump laser that produced very high peak-spectral-power irradiances. In the Doppler-broadening regime, this situation involves significant contributions from stimulated Raman scattering (SRS).

© 1995 Optical Society of America