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

Abstract

The depletion kinetics of excited-state Cr(a⁵D_J, 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(a⁵D_J, a⁵S₂) but an increase in populations of these states. This was attributed to relaxation of higher lying excited states to Cr(a⁵D_J, 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(a⁵D_J) and Cr(a⁵S₂), respectively. The depletion rate constants for Cr(a⁵D_J) 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.