Photoelectron spectra of polysilanes. Conformational analyses of tetra-and penta-silane

The p.e. spectra of polysilanes SinH2n+2(n= 2,3,4,5) are presented. Whereas assignment is uncomplicated for n= 2 or 3, p.e. spectroscopic conformational analyses are necessary for tetra- and penta-silane. Their p.e. spectra can be simulated by CNDO eigenvalues (Iµ) if various rotamers are taken into account. For this procedure the relation ΔIµi,j≈Δ(ionisation energy)i,j must hold. Comparison of experimental and simulated spectra allows determination of the ratios of rotamers of Si4H10 and Si5H12 present under the p.e. spectroscopic conditions.