title: Communication: A rotationally resolved (2OH) overtone band in the water dimer (H₂O)₂.
abstract: Cw-CRDS spectra of water-rare gas supersonic expansions were recorded between 7229 and 7262 cm(-1). The effective absorption pathlength was about 1 km in jet-cooled gas and the resolution about 1 × 10(-4) cm(-1). Many well-resolved structures are observed that could be assigned from experimental evidence to H2O-Ar/Kr bands. Eight broader unresolved features are more specifically reported and assigned to small H2O multimers, in good agreement and refining previous observations by Nizkorodov et al. [J. Chem. Phys. 122, 194316 (2005)]. Among these, the band at 7256.5 cm(-1) is shown to be a Q branch of the water dimer with accompanying R and very weak P lines. The band is assigned to a K(a) = 0 ← 1 transition and rotationally analyzed, leading to a restricted set of upper state rotational constants. The upper state lifetime (60 ± 3 ps) is extracted from the linewidths.
authors.affiliation: Laboratoire de Chimie Quantique et Photophysique, CP160/09 Faculté des Sciences, Université Libre de Bruxelles, Ave. F. D. Roosevelt 50, B-1050 Brussels, Belgium.
authors.forename: T
authors.initials: T
authors.lastname: Földes
authors.affiliation: Laboratoire de Chimie Quantique et Photophysique, CP160/09 Faculté des Sciences, Université Libre de Bruxelles, Ave. F. D. Roosevelt 50, B-1050 Brussels, Belgium.
authors.forename: T
authors.initials: T
authors.lastname: Vanfleteren
authors.affiliation: Laboratoire de Chimie Quantique et Photophysique, CP160/09 Faculté des Sciences, Université Libre de Bruxelles, Ave. F. D. Roosevelt 50, B-1050 Brussels, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Herman