The direct ultraviolet absorption spectrum of the 1Σg+ → 1B2(1Σu+) transition of jet-cooled 13C32S2 and 12C34S2

The absorption spectra of isotopically substituted carbon disulfide, i.e., 13C32S2 and 12C34S2, cooled in supersonic expansion are reported here and compared with the spectrum of the natural isotope. Cooling these samples eliminated spectral congestion due to inhomogeneous factors and yielded measurements of frequencies and isotopic shifts of bands of 13C32S2 and 12C34S2 relative to 12C32S2. The spectrum obtained is interpreted to reflect a transition from a linear ground state to a bent excited state up to ∼49 000 cm−1 and to a quasilinear excited state above this energy.