Temperature dependent quenching of CH(A2Δ), NH(A3Π), NH(c1Π), and PH(A3Π) by H2 Original Research Article

The kinetics of the quenching of electronically excited NH(c1Π), NH(A3Π), PH(A3Π), and CH(A2Δ) radicals in collisions with H2 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 photolysis of appropriate parent molecules. Together with low temperature 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 to the corresponding dissociation/association systems AH3 ⇔ AH∗ + H2 and ab initio calculation thereof.