TEMPERATURE-DEPENDENT QUENCHING OF CH(A(2)DELTA), NH(A (3)PI), NH(C (1)PI), AND PH(A (3)PI) BY H-2

The kinetics of the quenching of electronically excited NH(c(1)II), NH (A(3)II), PH(A(3)lI), and CH(A(2) Delta) radicals in collisions with H -2 was investigated in the temperature range 300 to about 1000 K. The reaction systems were heated by pulsed IR radiation from a CO2 laser. The excited states were generated in the heated systems by ArF laser p hotolysis of appropriate parent molecules. Together with low temperatu re data, this study shows that the quenching of NH(c), NH(A), and PH(A ) occurs without a barrier on the reaction paths while the removal of CH(A) exhibits an activation energy. These processes will be related t o the corresponding dissociation/association systems AH(3) double left right arrow AH + H-2 and ab initio calculation thereof.