title: Production of B atoms and BH radicals from B2H6/He/H2 mixtures activated on heated W wires.
abstract: B atoms and BH radicals could be identified by laser-induced fluorescence when B2H6/He/H2 mixtures were activated on heated tungsten wires. The densities of these radical species increased not only with the wire temperature but also with the partial pressure of H2. The densities in the presence of 0.026 Pa of B2H6 and 2.6 Pa of H2 were on the order of 10(11) cm(-3) both for B and BH when the wire temperature was 2000 K. Densities in the absence of a H2 flow were much smaller, suggesting that the direct production of these species on wire surfaces is minor. B and BH must be produced in the H atom shifting reactions, BH(x) + H → BH(x-1) + H2 (x = 1-3), in the gas phase, while H atoms are produced from H2 on wire surfaces. The B atom density increased monotonously with the H atom density, while the BH density showed saturation. These tendencies could be reproduced by simple modeling based on ab initio potential energy calculations and the transition-state theoretical calculations of the rate constants. The absolute densities could also be reproduced within a factor of 2.5.
authors: Graduate School of Engineering and §Faculty of Engineering, Shizuoka University , Johoku, Naka, Hamamatsu, Shizuoka 432-8561, Japan.
authors: Hironobu
authors: H
authors: Umemoto
authors: Taijiro
authors: T
authors: Kanemitsu
authors: Akihito
authors: A
authors: Tanaka