Infrared spectra of C2H4 dimer and trimer

Spectra of ethylene dimers and trimers are studied in the nu11 and (for the dimer) nu9 fundamental band regions of C2H4 (~2990 and 3100 cm-1) using a tunable optical parametric oscillator source to probe a pulsed supersonic slit jet expansion. The deuterated trimer has been observed previously, but this represents the first rotationally resolved spectrum of (C2H4)3. The results support the previously determined cross-shaped (D2d) dimer and barrel-shaped (C3h or C3) trimer structures. However, the dimer spectrum in the nu9 fundamental region of C2H4 is apparently very perturbed and a previous rotational analysis is not well verified.Comment: 21 pages, 4 figure

Three new infrared bands of the He-OCS complex

Three new infrared bands of the weakly-bound He-OCS complex are studied, using tunable lasers to probe a pulsed supersonic slit jet expansion. They correspond to the (0400) <-- (0000), (1001)<-- (0000), and (0401) <-- (0000) transitions of OCS at 2105, 2918, and 2937 cm-1, respectively. The latter band is about 7900 times weaker than the previously studied OCS nu1 fundamental. Vibrational shifts relative to the free OCS monomer are found to be additive. Since carbonyl sulfide has previously been shown to be a valuable probe of superfluid quantum solvation effects in helium clusters and droplets, the present results could be useful for future studies of vibrational effects in such systems.Comment: 16 pages, 1 figure, 4 table

Infrared diode laser spectroscopy of the CCO radical: the 2v1-v1 and v1+v3-v3 difference bands

Sherpa Romeo green journal. Permission to archive final published version. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.The 2n 12n 1 and n 11n 32n 3 difference bands of the CCO radical in the gas phase have been studied using a tunable infrared diode laser spectrometer. The CCO radical was produced using a flowing mixture of carbon suboxide and helium subjected to a hollow-cathode discharge. The spectral region between 1920– 1960 cm21 was probed. Ninety and seventy-five rovibrational transitions were measured in the 2n 12n 1 and n 11n 32n 3 bands, respectively. The analyses of these bands yielded spectroscopic constants for the ~001!, ~200!, and ~101! vibrational states. The band origins for 2n 12n 1 and n 11n 32n 3 were determined to be 1941.85761(54) cm21 and 1936.79402(56) cm21, respectively.Ye

Doped rare gas clusters up to completion of first solvation shell, CO2-(Rg)n, n = 3-17, Rg = Ar, Kr, Xe

Spectra of rare gas atom clusters containing a single carbon dioxide molecule are observed using a tunable mid-infrared (4.3 micron) source to probe a pulsed slit jet supersonic expansion. There are relatively few previous detailed experimental results on such clusters. The assigned clusters include CO2-Arn with n = 3, 4, 6, 9, 10, 11, 12, 15, and 17, as well as CO2-Krn and -Xen with n = 3, 4, and 5. Each spectrum has (at least) partially resolved rotational structure, and each yields precise values for the shift of the CO2 vibrational frequency (nu3) induced by the nearby rare gas atoms, together with one or more rotational constants. These results are compared with theoretical predictions. The more readily assigned CO2-Arn species tend to be those with symmetric structures, and CO2-Ar17 represents completion of a highly symmetric (D5h) solvation shell. Those not assigned (e.g. n = 7, 13) are probably also present in the observed spectra, but with band structures which are not well-resolved and thus not recognizable. The spectra of CO2-Ar9, -Ar15, and -Ar17 suggest the presence of sequences involving very low frequency (~2 cm-1) cluster vibrational modes, an interpretation which should be amenable to theoretical confirmation (or rejection).Comment: 34 pages, 12 figures, 9 table

Infrared spectra of the water-CO2 complex in the 4.3-3.6 micron region and determination of the ground state tunneling splitting for HDO-CO2

Spectra of water-CO2 dimers are studied using a tunable mid-infrared source to probe a pulsed slit jet supersonic expansion. H2O-CO2 and D2O-CO2 are observed in the CO2 nu3 fundamental region (~2350 cm-1), D2O-CO2 is also observed in the D2O nu3 fundamental region (~2790 cm-1), and HDO-CO2 is observed in the HDO O-D stretch fundamental region (~2720 cm-1), all for the first time in these regions. Analysis of the spectra yields excited state rotational parameters and vibrational shifts. They also yield the first experimental values of the ground state internal rotation tunneling splittings for D2O-CO2 (0.003 cm-1) and HDO-CO2 (0.0234 cm-1). The latter value is a direct determination made possible by the reduced symmetry of HDO-CO2. These results provide stringent and easily interpreted tests for theoretical water - CO2 potential energy surface calculations.Comment: 19 pages, 6 figure and 5 table