KINETICS OF TI(A(3)F, A(5)F) AND V(A(4)F, A(6)D) DEPLETION BY NH3 ANDH2S

The kinetics of depletion of ground-state Ti(a(3)F) and V(a(4)F) and e xcited-state Ti(a(5)F) and V(a(6)D) upon interactions with NH3 and H2S are studied in a fast-flow reactor at a He pressure of 0.70 Torr. No depletion of ground-state Ti(a(3)F) and V(a(4)F) was observed upon int eraction with NH3. Depletion of Ti(a(3)F) and V(a(4)F) by H2S did occu r but inefficiently, with measured effective 300 K bimolecular rate co nstants of (0.44 +/- 0.12) x 10(-12) and (4.0 +/- 0.2) x 10(-12) cm(3) s(-1), respectively. In contrast to the ground-state metals, depletio n of excited-state metal atoms Ti(a(5)F) and V(a(6)D) by NH3 and H2S o ccurred efficiently. The measured effective rare constants for depleti on of Ti(a(5)F) by NH3 and H2S are (39 +/- 11) x 10(-12) acid (142 +/- 13) x 10(-12) cm(3) s(-1), respectively. The measured rate constants for depletion of V(a(6)D) with these respective gases an (95 +/- 8) x 10(-12) and (69 +/- 5) x 10(-12) cm(3) s(-1). The reactive differences between the ground and excited states as well as between metals provi de important clues about N-H and S-H bond activation in these systems.