TRANSLATIONALLY AND ROTATIONALLY RESOLVED EXCITATION OF CO2(00(0)2 BYCOLLISIONS WITH HOT HYDROGEN-ATOMS

Time domain tunable diode laser absorption spectroscopy has been used to measure rotationally resolved transient absorption line shapes and nascent rotational populations for CO2 molecules excited into the (00( 0)2) vibrational state by collisions with translationally hot hydrogen atoms. The 00(0)2 rotational population distribution and rotationally resolved linewidths are remarkably similar to those previously obtain ed for 00(0)1. Within the context of a simple physical model used to i nterpret the data, the similar rotational distributions and translatio nal recoils for 00(0)1 and 00(0)2 suggest that these two states are ex cited by similar collision trajectories, wherein asymmetric stretching excitation is optimized when H strikes near the end of the O-C-O mole cule. The magnitude of population scattered into 00(0)2 is approximate ly 21 times smaller than that scattered into 00(0)1.