High-resolution laser spectroscopy of the [formula omitted]1[formula omitted] – [formula omitted]1[formula omitted] transition of 13C12C12C and 12C13C12C

Abstract

We present a laser spectroscopic study of the Ã1Πu – X̃1Σg+ transition of 13C mono-substituted C3 in the 378–406 nm region. The 13C12C12C and 12C13C12C isotopologues are produced in a pulsed jet expansion, by DC discharging a gas mixture of ∼0.3% C2H2/Ar (with ∼1% 13C natural abundance). By using laser induced fluorescence spectroscopy, thirteen vibronic bands belonging to the Ã1Πu – X̃1Σg+ electronic transition have been recorded for 13C12C12C and 12C13C12C, eleven of which have not been reported before. The transitions cover the three fundamental vibrational modes (ν1,ν2l,ν3). For all the vibronic bands, the full width at half maximum of spectral lines is found to be narrower than 0.023 cm-1, allowing to determine the transition frequencies with an absolute accuracy of ∼0.003 cm-1. Moreover, rotational analyses of the high-resolution data have yielded accurate spectroscopic constants for the upper vibronic states studied here. The 100–000, 04+0–000 and 12−0–000 bands of 13C12C12C, and the 02+0–000 and 04−0–000 bands of 12C13C12C are found to be less blended by spectral features of 12C3, and thus may be used for astronomical searches of 13C12C12C and 12C13C12C in the space.