MULTIPHOTON IONIZATION OF SIH3 AND SID3 RADICALS .2. 3 PHOTON RESONANCE-ENHANCED SPECTRA OBSERVED BETWEEN 450 AND 610 NM

The electronic spectra of silyl radicals, SiH3 and SiD3, were observed between 450 and 610 nm (49 200-65 200 cm-1) by resonance enhanced multiphoton ionization (REMPI) spectroscopy. The spectra were produced through a 3 + 1 REMPI mechanism. Spectra of four new planar Rydberg states were observed and assigned. In SiH3 the observed states and spectroscopic constants are D approximately 2 A 1' (3d):T0 = 49 787(30), omega-2 = 810(31) cm-1; I approximately' (4d): T0 = 56 253(30), omega-2 = 814(25) cm-1; J approximately' (4d):T0 = 57 726(30), omega-2 = 835(26) cm-1; and L approximately (5d):T0 = 59 615(30) cm-1, omega-2 = 839(26) cm-1. In SiD3 the observed states and spectroscopic constants are D approximately 2 A 1' (3d):T0 = 49 685(30), omega-2 = 600(28) cm-1; I approximately' (4d):T0 = 56 205(30), omega-2 = 600(17) cm-1; and J approximately' (4d):T0 = 57 840(30), omega-2 = 603(20) cm-1. The differences between 2 + 1 and 3 + 1 REMPI spectra are explained by a DELTA-l rule, where l is the electronic orbital angular momentum. The H approximately, K approximately, and N approximately states observed in the 2 + 1 REMPI spectrum of SiD3 spectrum and reported in J. Chem. Phys. 91, 3340 (1989) are reassigned as the H approximately 2 E' (4p), K approximately 2 E' (4f), and N approximately 2 E' (5f).