Laser photoelectron spectrometry of the negative ions of silicon and its hydrides

摘要

Fixedminus;frequency laser photoelectron spectrometry has been utilized to study the ions Siminus;, SiHminus;, and SiHminus;2. In each case, the photodetached electron energy spectrum consists primarily of sharp, easily assignable peaks. The electron affinities of Si, SiH, and SiH2have been determined to be (1.385plusmn;0.005) eV, (1.277plusmn;0.009) eV, and (1.124plusmn;0.020) eV, respectively. Two bound excited states attributed to2Dand2Pterms have been observed for Siminus;, and their binding energies determined. Similarly, two bound excited states, assigned to1Dgr; and1Sgr;+symmetry, have been discovered in SiHminus;. The internuclear distancerein the ground state of SiHminus;has been determined by a Franckminus;Condon factor analysis to be (1.474plusmn;0.004) Aring;. In addition, spectroscopic constants of the excited states have been deduced. Transitions from the ground state of SiHminus;to both the1A1and3B1states of SiH2have been observed; unlike the case of CH2, the1A1state is the lower in energy.