Theoretical study of the electronic spectrum of SiH4

A b initio SCF calculations of the first excited states of SiH4 are reported. Earlier experimental assignments of the three broad peaks in the 107–220 nm range are discussed in terms of the analysis of calculated charge transfer for each state. It is clearly seen that only the first band can be attributed to a pure 4s Rydberg transition, while the others result from an overlapping of diffuse 3d states with the first antibonding Si–H level. The shoulder at 118 nm is assigned to the 5s atomic transition.