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Abstract: The pure rotational spectrum of 175Lu16O in its ground electronic state (X 2Σ+) has been observed with a cavity pulsed jet Fourier transform microwave spectrometer. The samples were prepared by laser ablation of Lu metal in the presence of gaseous oxygen, and stabilized in pulsed jets of Ar. The N =1–0 transition has been measured in the v = 0, 1 and 2 states. All the observed lines show Zeeman splittings caused chiefly by the Earth’s magnetic field. The transitions show effects of electron spin-rotation structure and of 175Lu hyperfine structure. Several hyperfine parameters have been evaluated, and are interpreted in terms of the molecular electronic structure. An improved equilibrium internuclear distance, r e, is presented. The results should facilitate astrophysical searches for the molecule. [Copyright &y& Elsevier]

Abstract: Tin metal has been ablated with pulsed radiation from a Nd:YAG laser ( nm). Carbonyl sulfide, diluted in high pressure argon, has been pulsed into the resultant Sn plasma. One of the results of this experiment has been the production of SnS. These events have allowed a rotational spectrum of tin monosulfide to be studied using a chirped-pulse Fourier transform microwave spectrometer. The resolution of the spectrum obtained was sufficient to observe hyperfine structure from the 117Sn and 119Sn-containing SnS molecules. Tin nuclear spin-rotation hyperfine constants are reported for the first time. [Copyright &y& Elsevier]

Abstract: An experimental study has been performed shedding light on the conformational energies of the asymmetric ether n-butyl ethyl ether. Rotational spectroscopy between 7.8GHz and 16.2GHz has identified two conformers of n-butyl ethyl ether, C4H9OC2H5. In these experiments spectra were observed as the target compound participated in an argon expansion from high to low pressure causing molecular rotational temperatures to be below 4K. For one conformer, 95 pure rotational transitions have been recorded, for the second conformer, 20 pure rotational transitions were recorded. Rotational constants and centrifugal distortion constants are presented for both butyl ethyl ether conformers. The structures of both conformers have been identified by exploring the multi-dimensional molecular potential energy surface using ab initio calculations. From the numerous low energy conformers identified using ab initio methods, the three lowest conformers were pursued at increasingly higher levels of theory, i.e. complete basis set extrapolations, coupled cluster methods, and also taking into consideration zero point vibrational energies. The two conformers observed experimentally are only revealed to be the two lowest energy conformers when high levels of quantum chemical methodologies are employed. [Copyright &y& Elsevier]

Abstract: The pure rotational spectrum of tin monochloride, SnCl, has been measured and analyzed using chirped pulse and cavity Fourier transform microwave spectrometers equipped with a laser ablation source. SnCl, in its electronic state, has been measured in the 8–17GHz region. Rotational constants, centrifugal distortion constants, Λ-doubling constants, magnetic hyperfine constants, and nuclear electric quadrupole coupling constants for multiple isotopologues have been determined and are reported. The bond length, nuclear magnetic and quadrupole constants have been analyzed and compared against the family of tetral halides. Analysis of the bond length and hyperfine interactions point to a Sn–Cl single bond which is largely ionic in nature. [Copyright &y& Elsevier]

Abstract: The effects of partial fluorination on acetone have been examined using broadband rotational spectroscopy within the 7.5–16.5GHz region. The broadband spectrum, which contains information on the methyl group internal rotation, was analyzed using a principal axis method, and subsequently analyzed using (i) a combined axis method and (ii) a method in which the Hamiltonian possesses matrix elements expressed as Fourier series. Spectroscopic constants and effective barriers to methyl group internal rotation are presented for the first time. Results are compared to related molecules where it is shown that the carbonyl group effectively limits the effects of fluorination on the adjacent C(ph name="sbnd" />CH3 structure. The spectroscopic analyses performed demonstrate a satisfactory convergence of the Hamiltonian in all combinations of Watson reduction and representation with the exception of A and I r . Within this combination the ratio (2A − B − C)/(B − C) is large resulting in unreasonably large values of the quartic centrifugal distortion constant δ K which in turn prohibits a satisfactory eigenvalue solution. [Copyright &y& Elsevier]

Abstract: The first far-infrared high resolution absorption measurement of the cis-methyl nitrite molecule has been recorded in the range 15–400cm−1 using the synchrotron AILES beamline radiation at SOLEIL with a resolution of 0.0011cm−1. First assignments for the pure rotational transitions (15–65cm−1) belonging to the ground νt (=ν 15)=0 and first νt =1 excited torsional state are based on measurements from previous studies performed in the 13–40GHz spectral range, as well as on new millimeter-wave measurements performed at Lille in the spectral range 75–465GHz. A few measurements and remeasurements in the 1.8–13GHz were also performed using the chirped FT-MW spectrometer located in North Texas. The pure rotational transitions in the far-infrared and in the microwave spectral range belonging to the two first torsional states have been globally fitted using the RAM (“Rho Axis Method”) dealing with the rotation–torsion Hamiltonian and implemented in the BELGI code. A total of 708 and 713 microwave transitions (6⩽ J ⩽40, ⩽23) belonging to the ground torsional state νt =0 and 1 have been fitted with root-mean-square (rms) deviations of 37.4kHz and 32.3kHz respectively, and 3170 pure rotational transitions in the far-infrared range (12⩽ Jmax ⩽65, 0⩽ ⩽48) belonging to νt =0 and 1 have been fitted with a rms deviation of 0.00017cm−1, using 35 parameters. Since in the far-infrared spectral range, the A–E internal rotor splittings have not been observed for the transitions belonging to the torsional ground νt =0 state of the cis-methyl nitrite species, another fit was performed on those lines, using a Watson type Hamiltonian for comparison. [Copyright &y& Elsevier]

A chirped pulse microwave spectrometer has been used to record microwave spectra of the 35Cl and 37Cl isotopologues of methyl chlorodifluoroacetate, CClF2C(=O)OCH3, between 8 GHz and 16 GHz. The target compound was spectroscopically examined as it participated in a supersonic expansion of argon. Only one conformer was observed. The rotational spectra were recorded with sufficient resolution to observe (i) splittings due to the internal rotation of the methyl group, and (ii) splittings from the coupling of the chlorine quadrupolar nucleus. A total of 785 transitions have had quantum numbers assigned. Analysis of the spectra observed has produced an experimental barrier to the methyl group internal rotation, V3, of 370(2) cm−1. It is noted that this barrier is a little lower than that determined for methyl acetate [V3 = 425 cm−1, J. Sheridan, W. Bossert and A. Bauder, J. Mol. Spectrosc., 80 (1980) 1–11], and this is rationalized through a comparison of molecular structures. Lastly, all components of both the 35Cl and 37Cl chlorine nuclear electric quadrupolar coupling tensor have been determined. [ABSTRACT FROM AUTHOR]

Abstract: A search accelerated correct intensity Fourier transform microwave (SACI-FTMW) spectrometer has been used to rapidly record the rotational spectrum of pivaloyl chloride between 8 and 18GHz. Both a radio frequency and regular cavity-based instrument have then been used to obtain high resolution measurements below 4GHz and in the 4–18GHz regions, respectively. Rotational constants, centrifugal distortion constants, and chlorine nuclear quadrupole coupling constants have been determined for both the 35Cl and 37Cl isotopologues. The spectrum provides no evidence concerning internal rotation in the molecule. [Copyright &y& Elsevier]