Collisional deactivation of vibrationally excited singlet molecular oxygen

Abstract

Measurements of the collisional deactivation time of the ν′ = 1 vibrational level of the ¹Δ_g electronic state have been made using a high pressure gas cell equipped with an acoustic detector. To separate relaxation effects from effects due to viscosity, thermal conductivity, cell geometry, and nonuniform irradiation by the laser beam a detailed theoretical treatment of the acoustical behavior of the cell was required. Application of these results to the existing system was carried out and used to determine the appropriate relaxation times from the experimental data. Accordingly it was determined that for pure oxygen p τ = 0.05 sec · atm. Addition of increasingly large amounts of He caused this value to fall steadily to a limiting value p τ = 0.016 sec · atm which agrees well with the data obtained by previous investigators for the ν′ = 0 vibrational level.