title: Infrared spectrum of the CS2 trimer: observation of a structure with D3 symmetry.
abstract: Infrared spectra of a carbon disulfide trimer formed in a pulsed supersonic slit-jet expansion are obtained via direct absorption of a tuneable diode laser in the region of the CS(2)ν(3) fundamental (∼1535 cm(-1)). This is the first high-resolution spectroscopic observation of (CS(2))(3). Two bands sharing the same lower state are assigned to ((12)C(32)S(2))(3). These correspond to the two infrared active trimer vibrations (a parallel and a perpendicular band) of the constituent CS(2) monomer asymmetric stretches. The weaker perpendicular band is centered at 1524.613 cm(-1), shifted by -10.74 cm(-1) with respect to the free CS(2) monomer. The parallel band is centered at 1545.669 cm(-1), a vibrational shift of +10.31 cm(-1). Transitions with K≠ 3n and those with K = 0, J = odd in the ground state are absent, establishing that this trimer has D(3) symmetry. The two parameters required to define this structure are determined to be 3.811 Å for the C-C bond distance and 61.8° for the angle between a monomer axis and the plane containing the C atoms. In addition, a parallel band arising from trimers with a single (34)S substitution is observed around 1544.46 cm(-1). Together with the recently observed cross-shaped CS(2) dimer, these results indicate a tendency for CS(2) to form highly symmetric clusters.
authors.affiliation: Department of Physics and Astronomy, University of Calgary, 2500 University Drive North West, Calgary, Alberta T2N 1N4, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Rezaei
authors.forename: J
authors.initials: J
authors.lastname: Norooz Oliaee
authors.forename: N
authors.initials: N
authors.lastname: Moazzen-Ahmadi
authors.forename: A R W
authors.initials: AR
authors.lastname: McKellar