Rotational Analysis of the E-X System of Silicon Monosulphide

The rotational analysis of twenty bands of the E-X system of SiS has been carried out. The system arises from a transition 1 Σ + - 1 Σ + , and, unexpectedly, no perturbations have been detected in E 1 Σ + . Constants (in cm -1 ) for the state E 1 Σ + , valid for 0 less-than-or-eq, slant ν less-than-or-eq, slant 7 are as follows: T 0 = 41743.8 6 , G ν = 406.8 3 (ν+½) - 1.95 2 (ν+½) 2 , B ν = 0.2213 7 - 0.0013 9 (ν+½) - 1· 75 × 10 -5 (ν+½) 2 . It seems probable that the state E is the 1 Σ + state arising from the configuration...π 3 σ 2 π * , analogous to the state B 1 Σ + u of the isoelectronic molecule P 2 .