Kinetics of excited-state Cr(a5DJ, a5S2) depletion by O2, NO, and N2

The depletion kinetics of excited-state Cr(a5DJ, a5S2) upon interaction with O2, NO, and N2 have been studied in a discharged flow reactor at He pressures of 0.5 and 0.7 Torr. The interaction with N2 showed no depletion of Cr(a5DJ, a5S2) but an increase in populations of these states. This was attributed to relaxation of higher lying excited states to Cr(a5DJ, a5S2). For the interactions with NO, the depletion rate constants are (115 ± 29) × 10−12 cm3 s−1 (over all J levels) and (36 ± 4) × 10−12 cm3 s−1 for Cr(a5DJ) and Cr(a5S2), respectively. The depletion rate constants for Cr(a5DJ) and Cr(a5S2) by O2 are (62 ± 14) × 10−12 cm3 s−1 (over all J levels) and (27 ± 11) × 10−12 cm3 s−1 respectively. Although the former is a factor of two larger, this difference is much smaller than the difference in the depletion rate constants for the same electronic states of Mo, another Group 6 metal atom. These results were discussed by schematic potential curves where ionic surfaces play an important role.