Deactivation of the bending mode v2′=1 and v2′=0 vibrational levels of PH2(Ã 2A1), and of the v2″=1 level of ground state PH2(X̃ 2B1) due to collisions with the diatomic molecules H2, N2, CO, and NO has been investigated. The Parmenter and co-worker’s, the Thayer and Yardley’s, and the collision complex theories have been used to rationalize the PH2(Ã 2A1) quenching data. Explanations for the deviations of the quenching data due to these molecular quenchers from the variation trend found, in a previous work, for the rare gas quenchers have been proposed. For the vibrational relaxation of PH2(X̃ 2B1;0,1,0), the data interpretation is based essentially on the theories by Schwartz, Slawsky, and Herzfeld–Tanczos, and Moore.
The deactivation constants of PH2(Ã2A1; v‘2 = 1,0) and PH2(X̃2B1; v‘ ‘2 = 1) which are due to collisions with
CO2, N2O, and SO2 have been measured. Comparisons with data due to rare gas and diatomic quenchers
have shown that the electronically excited PH2 species are probably quenched by multiple channel mechanisms
of both physical and chemical nature for SO2 and of prevalently physical nature for CO2 and N2O. A V−V
energy transfer is clearly responsible for the vibrational relaxation of PH2(X̃2B1; v‘ ‘2 = 1) by these triatomic
quenchers.
Collisional deactivation of the vibrational level v=1 of the bending mode by rare gases has been studied for both the excited à 2A1 and ground X̃ 2B1 electronic states of PH2. Quenching constants have been determined. While a non-SSH behavior has been observed in the dependence of the relaxation probability upon the mass of the collision partner in the ground state denoting a possible predominance of an intramolecular V–R energy transfer process, the cross sections fit quite well the Parmenter and co-workers’ potential well depth correlation rule for both the electronic states indicating that their interactions with the quenchers occur for both of them under the influence of long range attractive forces.
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