Overtone, 2NH (ν1+ν3) spectroscopy of NH3-Ar and NH3-Kr

• Published in: Molecular physics Vol. 113; no. 24; pp. 3934 - 3945
• Main Authors: Vanfleteren, T., Földes, T., Liévin, J., Herman, M.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 17.12.2015; Taylor & Francis Ltd
• Subjects: ammonia; CW-CRDS; lifetime; molecular complex; overtone spectroscopy; Spectrum analysis
• ISSN: 0026-8976; 1362-3028
• DOI: 10.1080/00268976.2015.1072252

We have recorded between 6561 and 6671 cm - 1 the spectrum of jet-cooled ammonia seeded in Ne, Ar and Kr, using continuous wave cavity ring-down spectroscopy (CW-CRDS). The equivalent absorption pathlength was around 750 m. Three bands are assigned to Π(1 1 )←Σ(0 0 ), Π(1 1 )←Π(1 0 ) and Δ(?)←Π(1 0 ) in the 2NH, ν 1 +ν 3 ←GS transition of the ortho NH 3 -Ar dimer. They are rotationally analysed and a simultaneous fitting procedure, together with one far-infrared ground state band from the literature is successfully achieved. A possible M j -dependent cooling process is reported. Only the first of these bands is observed in the ortho NH 3 -Kr dimer, and rotationally analysed. Individual line perturbations and anomalous line broadening effects are reported. A J-dependent vibrational predissociation lifetime with a mean value around 0.6 ns is obtained for the Π(1 1 ) sub-state in NH 3 -Ar and NH 3 -Kr. Two additional bands are assigned to NH 3 -Ar involving close Π upper sub-states. A group of close bands from the para dimer is identified in NH 3 -Ar. The energy of all observed ortho and para sub-states is extracted from the analysis. Finally, more bands are reported but their carriers could not be identified.