KINETICS OF EXCITED-STATE CR(A D-5(J), A S-5(2)) DEPLETION BY O-2, NO, AND N-2

The depletion kinetics of excited-state Cr(a D-5(J), a S-5(2)) upon in teraction with O-2, NO, and N-2 have been studied in a discharged flow reactor at He pressures of 0.5 and 0.7 Torr. The interaction with N-2 showed no depletion of Cr(a D-5(J), a S-5(2)) but an increase in popu lations of these states. This was attributed to relaxation of higher l ying excited states to Cr(a D-5(J), a S-5(2)). For the interactions wi th NO, the depletion rate constants are (115 +/- 29) x 10(-12) cm(3) s (-1) (over all J levels) and (36 +/- 4) x 10(-12) cm(3) s(-1)for Cr(a D-5(J)) and Cr(a S-5(2)), respectively. The depletion rate constants f or Cr(a D-5(J)) and Cr(a S-5(2)) by O-2 are (62 +/- 14) x 10(-12) cm(3 ) s(-1) (over all J levels) and (27 +/- 11) x 10(-12) cm(3) s(-1) resp ectively. Although the former is a factor or two larger, this differen ce is much smaller than the difference in the depletion rate constants for the same electronic states of Mo, another Group 6 metal atom. The se results were discussed by schematic potential curves where ionic su rfaces play an important role.