Measurement of Heterogeneous Deactivation of Vibrationally Excited Homonuclear Molecules at Solid Surfaces

摘要

Deactivation coefficients, gamma(v), of vibrationally-excited N2X(1) sigmag(+),v on alloys of aluminum, stainless steel alloys, a titanium alloy, gold, Pyrex glass and Teflon were determined from measurements of the wall relaxation rate coefficients for the v = 1 to 4 or 5 hot bands using CARS. A water-cooled positive column discharge was used to populate the vibrational states. The nitrogen gas flow rate was adjusted to optimize the observed decay of the populations. The excited gas was exposed to the tubular specimen surface for precisely controlled residence times. The BOXCARS configuration was used to measure only the gas that was exposed to the specimen surface. Extensive measurements on Pyrex gave gamma(1) values between 2.4 x 10(exp -4) and 6.7 x 10(exp -4) depending on the treatment history of the surface. The values for gamma(4) ranged from 2.9 x 10(exp -4) for the AMS 4943D alloy of titanium to approximately unity for the AMS 312 stainless steel alloy. The low value for titanium can be attributed to the oxide layer. The variation of k(v) with v was linear or nearly linear in all cases with slopes lower in most cases than the rate of increase of the vibrational-translational exchange rate with v.