The absorption spectrum of H2S between 9540 and 10 000 cm−1 by intracavity laser absorption spectroscopy with a vertical external cavity surface emitting laser

✍ Scribed by Yun Ding; Olga Naumenko; Shui-Ming Hu; Qingshi Zhu; Elena Bertseva; Alain Campargue

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 231 KB
• Volume: 217
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1016/s0022-2852(02)00037-1

✦ Synopsis

An Intracavity Laser Absorption Spectrometer (ICLAS) based on a Vertical External Cavity Surface Emitting Laser (VECSEL) has been used to record the absorption spectrum of H 2 S between 9540 and 10 000 cm À1 with pressures up to 122 Torr (160.5 hPa) and equivalent absorption path lengths up to 45 km. More than 1600 absorption lines were attributed to the transitions reaching the highly excited ð40 AE ; 0Þ, ð30 AE ; 2Þ, and ð11 þ ; 4Þ states (local mode notation). The existing information relative to the ð40 AE ; 0Þ local mode bright pair at 9911:02 cm À1 was considerably enlarged, while the other states are reported for the first time. Eight hundred and ninety two precise energy levels were derived, including 181 and 28 levels for the H 2 34 S and H 2 33 S minor isotopomers, respectively. These energy levels were fitted using a Watson-type rotational Hamiltonian and the spectroscopic parameters were obtained, yielding an rms deviation of 0:006 cm À1 for the H 2 32 S species-close to the experimental accuracy. The dark states-ð20 þ ; 4Þ and ð11 þ ; 4Þ-at 9647.77 and 9744:88 cm À1 , respectively, were found to perturb the observed energy levels and were then included into the final energy levels modeling. The ð40 AE ; 0Þ states are very close to the local mode limit, i.e., with a mostly identical rotational structure. The ð30 AE ; 2Þ states are separated by 0:077 cm À1 and this separation holds for most of the rotational sublevels. The resonance interactions between the three local mode pairs-ð40 AE ; 0Þ, ð30 AE ; 2Þ, and ð20 AE ; 4Þ-and the ð11 þ ; 4Þ state affect in some cases specifically one of the component of the pair and then the energy separation of the corresponding near degenerate rotational levels. Line intensities were obtained on the basis of the relative intensities measured by ICLAS and from absolute values of the stronger lines measured separately by Fourier Transform Spectroscopy associated with a multipass cell. The transition intensities could be successfully modeled and the integrated band intensities are given and discussed.