The emission spectrum of carbon monoselenide

Abstract

The emission spectrum of CSe was excited in an electrodeless discharge tube containing a mixture of carbon and selenium in the presence of argon by means of a high power microwave generator. Spectra were photographed on a 2 m Bausch and Lomb dual grating spectrograph in the first order of a grating with 1200 grooves/mm. Thirty-seven characteristic bands of CSe were obtained in the spectral region 3060 - 2680 Å. In addition to the previously known A¹π - X¹Σ⁺ system, a new band system has been identified for the first time. The wavenumbers of the band heads of the new system are represented by the relation, -- ν = 34702.2 + 954.9(v' + ½) - 6.9(v' + ½)² -- - [1039.9(v" + ½) - 8.4(v" + ½)²] . -- By correlating the ωₑ values of different electronic states of the analogous molecules CO, CS and CSe it is suggested that the transition giving rise to the new band system of CSe is probably a³π - X¹Σ⁺. -- A complete rotational analysis of the 0,1 band and a partial rotational analysis of the 1,2 , 1,1 , 0,0 , 2,1 and 1,0 bands of the A¹π - X¹Σ⁺ system, photographed at high resolution in the fifth order of the grating, are also reported. The rotational constants obtained for the lower and upper states are as follows: -- B"ᵥ = 0.577 - 0.0045 (v"+ ½) cm⁻¹ B'ₒ = 0.484 cm⁻¹ -- D" = 3 x 10⁻⁶ cm⁻¹ B'₁ = 0.489 cm⁻¹ -- r"ₑ = 1.673 Å B'₂ = 0.478 cm⁻¹ -- D' = 1 x 10⁻⁶ cm⁻¹ -- r'ₒ = 1.827 cm⁻¹ -- νₒₒ = 35135.51 cm⁻¹ . -- The values of B'ₑ and α'ₑ could not be determined from the obtained rotational constants because of perturbations in the upper state.