ν 6 and ν 8 infrared bands and force field of disilane

Abstract

The infrared absorption spectrum of the ν 6 and ν 8 bands of disilane (Si 2H 6) was recorded at medium resolution (0.1-0.05 cm −1). A rotation analysis of the P( J) and R( J) structure of ν 6 was carried out, yielding the band origin and information on the B constant of the ground and v 6 = 1 states of the molecule, and on the D J centrifugal distortion constant. About 400 transitions of the ν 8 band were assigned and analysed, giving information on the band origin and the rotational constants of the v 8 = 1 state. Using the new and previous information on the vibrational spectrum of Si 2H 6 and Si 2D 6, a force constant refinement was performed. Several force field models were tried and a discussion of the results is presented.