LASER VAPORIZATION GENERATION OF THE SIB AND SIAL RADICALS FOR MATRIX-ISOLATION ELECTRON-SPIN-RESONANCE STUDIES - COMPARISON WITH THEORETICAL CALCULATIONS AND ASSIGNMENT OF THEIR ELECTRONIC GROUND-STATES AS X (4)SIGMA

The first experimental spectroscopic study of the SiB and SiAl diatomi c radicals is reported. Electron spin resonance results indicate that both molecules have X4SIGMA ground electronic states, in agreement wit h earlier theoretical calculations. The SiB and SiAl radicals were gen erated in neon matrices at 4 K by trapping the products produced from the pulsed laser vaporization of their alloys. Electronic structure in formation for these radicals is especially interesting given the utili zation of silicon doped materials in semiconductor applications. The o bserved nuclear hyperfine interactions (A tensors) for B-10, B-11, and Al-27 in these molecular radicals were compared with the results of a b initio configuration-interaction theoretical calculations which were conducted as part of this experimental study. The neon matrix magneti c parameters (MHz) for (SiB)-B-11 are D = 800 (2), g (parallel-to) = 2 .0014 (8), g(perpendicular-to) = 2.0005 (4), A(perpendicular-to) = 92. 4 (5), and A(parallel-to) = 111(2). For (SiAl)-Al-27 the results (MHz) are D = 9 7 10 (2), g(parallel-to) = 1.9994(8), and g(perpendicular-t o) = 1.997 8(4), \A(perpendicular-to)\ = 10.3(6), and \A(parallel-to)\ = 43.5 (8).