Depletion Kinetics of Niobium Atoms in the Gas Phase

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 101; no. 18; pp. 3348 - 3355
• Main Authors: McClean, Roy E, Campbell, Mark L, Kölsch, Erica J
• Format: Journal Article
• Language: English
• Published: American Chemical Society 01.05.1997
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp963731n

The gas phase depletion kinetics of Nb(a6D J ,a4F J ) in the presence of O2, SO2, CO2, N2O, and NO are reported. Niobium atoms were produced by the 248 nm photodissociation of Nb(C5H5)(CO)4 and detected by laser-induced fluorescence. The ground term of Nb(4d45s a6D J ) reacts at or above the collision rate with all of the aforementioned oxidants. The first excited term, Nb(4d35s a4F J ), is not as reactive with these oxidants. Results are interpreted in terms of long-range attractions and valence interactions. Additionally, we report reaction rate constants for ground state Nb interacting with N2, CH4, and SF6. Nb(a6D J ) is unreactive toward CH4. Nb(a6D J ) + N2 is pressure dependent at 297 K with k 0 = (2.6 ± 0.3) × 10-32 cm6 s-1 and k ∞ = (4.1 ± 0.5) × 10-13 cm s-1. Nb(a6D J ) + SF6 is temperature dependent with the rate constants given by k(T) = (1.2 ± 0.3) × 10-10 exp[−(4.8 ± 0.2) kcal mol-1/RT] cm3 s-1. Depletion of the aF J term by N2, SF6, and CH4 is J-dependent.