Zero electron kinetic energy photoelectron and threshold photoionization spectroscopy of M-X[(C[H.sub.3]).sub.3] (M = Ga, In; X = P, As)

This paper presents pulsed-field ionization, zero electron kinetic energy (ZEKE) photoelectron and threshold photoionization spectra of M-X[(C[H.sub.3]).sub.3] (M = Ga, In; X = P, As). The ZEKE spectra exhibit well-resolved vibrational structures. A comparison with B3LYP calculations shows that the spectrum of In-P[(C[H.sub.3]).sub.3] arises from the [sup.1][A.sub.1] [left arrow] [sup.2]E transition and the spectra of Ga-P[(C[H.sub.3]).sub.3] and Ga-As[(C[H.sub.3]).sub.3] arise from transitions of a Jahn-Teller distorted doublet state to the [sup.1][A.sub.1] state. The intensifies of the [sup.1][A.sub.1]-[sup.2]E transition in the indium species are described with the Franck-Condon approximation, while the transitions in the gallium complexes are more complicated due to the dynamic Jahn-Teller effect. The adiabatic ionization potentials of Ga-P[(C[H.sub.3]).sub.3], In-P[(C[H.sub.3]).sub.3], and Ga-As[(C[H.sub.3]).sub.3] are 39 635, 38 930, and 40 322 [cm.sup.-1] respectively, and the ionization threshold of In-As[(C[H.sub.3]).sub.3] is -39 550 [cm.sup.-1]. The metal-ligand stretching frequencies are 143, 116, and 125 [cm.sup.-1] for [Ga.sup.+]-P, [In.sup.+]-P. and [Ga.sup.+]-As, respectively, and 96 [cm.sup.-1] for In-P. The intermolecular bending frequencies are 71, 65, and 42 [cm.sup.-1] for [Ga.sup.+]-P-C, [In.sup.+]-P-C. and [Ga.sup.+]-As-C, respectively, and 47 [cm.sup.-1] for In-P-C. In addition, ligand-based vibrational frequencies are determined for the C[H.sub.3] wag, P[C.sub.3] and As[C.sub.3] umbrella, and P-C stretching vibrations. Key words: ZEKE photoelectron, photoionization, DFT. gallium-phosphine, gallium-arsine, indium-phosphine, indium-arsine.