John G. Smith

The Millimeter-Wave Rotational Spectrum of CF3CCH in the Excited Vibrational State v10 = 2

Abstract The millimeter-wave rotational spectra of the excited vibrational state ν 10 = 2 of the symmetric top species 3,3,3-trifluoropropyne (trifluoromethylacetylene), CF 3 CCH, have been recorded for J ″ = 12 up to J ″ = 34. The l = ±2 and l = 0 series have been assigned and the spectra analyzed to give rotational parameters including x ll = 8260.44 MHz. The main interactions between states of different l are the r t (2, −1) and q + t (2, 2) interaction terms. Two types of l -resonance are identified, one of which is due to an avoided crossing between the l = 0 and l = 2 series.

The millimetre wave spectrum of trichlorosilane

Abstract Millimetre wave rotational spectra have been recorded for Si 35 Cl 3 H in the ground and v 6 = 1 excited vibrational state. The l -resonance in the latter has been analysed. The asymmetric top species Si 37 Cl 35 Cl 2 H has been subjected to a centrifugal distortion constant analysis and the results of this and the parent isotopic species constants have been used to determine the harmonic force field of the molecule.

Analysis of the quadrupole coupling in the millimeter-wave spectrum of trichlorosilane

Abstract The splittings due to the three chlorine quadrupoles, observed in the millimeter-wave rotational spectra of Si 35 Cl 3 H in the ground and ν 6 = 1 excited vibrational states, have been analyzed and the quadrupole parameters determined. In particular, splittings observed for the kl − 1 = −1 lines in ν 6 = 1 are explained in terms of the asymmetry parameter η Q . The value obtained is consistent with the electric field gradient at the 35 Cl nuclei having cylindrical symmetry about the SiCl bond.

Millimeter-wave spectra of 2-chloro-2-methylpropane

Abstract The millimeter-wave rotational spectra of 2-chloro-2-methylpropane have been recorded and analyzed for the ground and several excited vibrational states. For all three of the doubly degenerate vibrations, moderate l-resonance occurs and Coriolis constants have been determined. The quadrupole splitting due to the chlorine nucleus has been analyzed.

The millimeter-wave spectrum of CF3C35Cl3 in its ground and excited vibrational states

Abstract The millimeter-wave rotational spectrum of CF 3 C 35 Cl 3 has been recorded. For the ground state, the results are in agreement with previous work; the very small value of D JK results in no measurable k -splitting. The rotational spectra of the torsional states have been recorded for v 6 = 1 to v 6 = 5. In addition, the rotational spectrum in the lowest doubly degenerate excited state has been analysed to yield values of the l -resonance parameters q i + = 0.7474(6) MHz and A ζ t = 283.2(2) MHz.

Direct observation of the ν6 band in the IR spectrum of CF3I dissolved in liquid xenon

Abstract The IR spectrum of CF3I dissolved in liquefied xenon at 185 K shows a very weak peak at 265.2 cm−1 due to the ν6 fundamental vibration. The separation, ν 3  ν 6, 19.3 cm−1 is the same as that deduced from the microwave spectrum of CF3I in the gas phase.

The millimeter-wave spectrum of methyltrichlorosilane

Abstract The millimeter-wave rotational spectra of CH 3 SiCl 3 have been recorded and analyzed for both the ground and the two lowest degenerate fundamental vibrational states. The quadrupole splitting due to the presence of three 35 Cl nuclei has been analyzed for the ground state. For the two excited states, the l -resonance has been analyzed and values of the Coriolis constants have been determined. The C rotational constant has been determined for one of these states.

The millimeter-wave spectrum of trifuooromethylsilane

Abstract Millimeter-wave rotational spectra have been recorded for trifluoromethylsilane in its ground and some excited vibrational states. The l resonance in two of the degenerate vibrations has been analyzed in detail to yield Coriolis constants ζ12z = 0.2531(1) and ζ11z = −0.6955(46). The 13C isotopic species has been located for the first time. These results confirm previous work on the structure and force field of this molecule.

The millimeter-wave spectrum of trimethylphosphine

Abstract Millimeter-wave rotational spectra have been recorded for trimethylphosphine in its ground and some excited vibrational states. The l-resonance in two of the degenerate vibrations has been analyzed in detail. Internal rotation effects in one of these states are described.