Toshiaki Okabayashi

Millimeter and submillimeter wave spectroscopy of HNC and DNC in the vibrationally excited states

The rotational transitions of hydrogen isocyanide (HNC) and deuterium isocyanide (DNC) in the vibrationally excited states as well as in the ground states were observed in the millimeter and submillimeter wave region. These compounds were generated in a dc glow discharge plasma containing hydrogen (or deuterium), nitrogen, and carbon atoms. The stretching vibrational modes, ν1 and ν3 states, were selectively excited in the discharge plasma; on the other hand, the bending mode ν2 state was thermally populated at the cell temperature. The precise rotational, centrifugal distortion and l‐type doubling constants were obtained for all of the first vibrationally excited states as well as the ground states. The experimental equilibrium rotational constants Be are 45 496.7769(45) and 38 207.7217(105) MHz for HNC and DNC, respectively, where uncertainties correspond to one standard deviation. The equilibrium internuclear distances are also determined to be re (H–N)=0.996 0643(29) A and re (N≡C)=1.168 3506(16) A.

Millimeter- and submillimeter-wave spectroscopy of AuF in the ground X1Σ+ state

Abstract The millimeter- and submillimeter-wave spectrum of AuF in the X 1 Σ + state was observed by employing a source-modulated microwave spectrometer. The AuF molecule was generated in a free space cell by the sputtering reaction from a gold sheet lining the inner surface of a stainless steel cathode using a dc glow plasma of CF 4 and Ar. Rotational transitions in the highly excited vibrational states enabled to determine Dunham-type molecular constants by a least-squares fit. Other constants like dissociation energy D e , vibrational wavenumber ω e and its anharmonic term ω e x e were also derived from the obtained constants.

Laboratory Rotational Spectrum of Nickel Monochloride in the Ground Electronic 2Π3/2 State

The pure rotational spectrum of nickel monochloride in the 2Π3/2 ground electronic state has been observed in the laboratory for the first time in the millimeter- and submillimeter-wave region. The NiCl radical was generated in a free-space absorption cell by a DC glow discharge in a mixture of Cl2 and Ar using a nickel cathode, from which nickel atoms were supplied by the sputtering reaction. The rotational, centrifugal distortion, and fine-structure constants were determined by a least-squares method using an effective Hamiltonian for a 2Π3/2 electronic state.

Microwave spectrum of FeCl radical in the electronic ground 6Δi state

Abstract The rotational spectrum of the FeCl radical in the electronic ground state was observed by using a source-modulated millimeter-wave spectrometer. This species was produced in a free-space cell by glow-discharging a mixture of helium and aluminum trichloride vapor. Iron atoms were extracted during the discharge from the stainless-steel electrodes in the cell. The spectrum was observed for the two lowest-lying spin components of the inverted sextet Δ state. The rotational and centrifugal distortion constants were determined by a least-squares fit to the line frequencies of each spin substate.

The rotational spectrum of the CrF radical in the X 6Σ+ state

The rotational spectrum of the CrF radical in the X 6Σ+ state was observed by employing a source modulation microwave spectrometer. The CrF radical was generated in a free space cell by a dc glow discharge in CF4 and He. The chromium atom was supplied by the sputtering reaction from chromium powder placed over a lower surface of the cylindrical electrodes. The transitions with N=12−11 to 20−19 were measured in the region between 270 and 460 GHz. The rotational, centrifugal distortion and several fine‐structure constants were obtained by a least squares analysis.

Low-energy vibrations of the group 10 metal monocarbonyl MCO (M = Ni, Pd, and Pt): rotational spectroscopy and force field analysis.

The rotational spectra of NiCO and PdCO in the ground and ν(2) excited vibrational states were observed by employing a source-modulated microwave spectrometer. The NiCO and PdCO molecules were generated in a free space cell by the sputtering reaction of nickel and palladium sheets, respectively, lining the inner surface of a stainless steel cathode with a dc glow plasma of CO and Ar. The molecular constants of NiCO and PdCO were determined by least-squares analysis. By force field analysis for the molecular constants of not only NiCO and PdCO but also of PtCO as previously reported, the harmonic force constants were determined for these three group 10 metal monocarbonyls. The vibrational wavenumbers derived for the lower M-C stretching vibrations were in good agreement with those obtained from the IR spectra in noble gas matrices and those predicted by several quantum chemical calculations published in the past. The bending vibrational wavenumbers derived by the force field analysis were also consistent with most quantum chemical calculations previously reported, but showed systematic discrepancies from the matrix IR values by about 40 cm(-1), even after reassignment (ν(2) band → 2ν(2) band) of the matrix IR spectra of PdCO and PtCO.

Detection of Free Monomeric Silver(I) and Gold(I) Cyanides, AgCN and AuCN: Microwave Spectra and Molecular Structure

The chemistry of the group 11 metal cyanide system has been of considerable interest because of the commercial importance of some of the complexes formed in this system. These metal cyanides contain one-dimensional linear -M-CN-M-CN-M- chains in the solid state; however, they have not been observed as free monomeric species. This Article reports the first detection of monomeric AgCN and AuCN in the gas phase by using rotational spectroscopy. The sputtering reaction of silver and/or gold sheets placed on a stainless steel cathode with CH3CN diluted in Ar resulted in the production of AgCN and AuCN spectra. Spectroscopic observation of the parent and several rare isotopic species allowed the determination of r(0), r(s), r(Iepsilon), r(m)(1), and r(m)(2) structures in the case of AgCN and r(0) and r(s) structures in the case of AuCN. All data indicate that these two species have a linear MCN geometry with a low-energy bending vibration.

MICROWAVE SPECTROSCOPIC STUDY OF THE BBR MOLECULE

Abstract The reactive species BBr was produced by the glow discharge of the BBr 3 vapor in a free space cell. Rotational spectra of the four isotopic species were observed between 117 and 480 GHz. For lower rotational transitions the hyperfine structure owing to the bromine nucleus has been observed, and from its analysis the nuclear quadrupole interaction constant has been determined. The breakdown of the Born-Oppenheimer approximation for the rotational constant was recognized and the relevant parameters were determined.

Laboratory Measurement of the J = 1-0 Transition of Copper Hydride

The J = 1-0 transitions of 63CuH and 65CuH were measured in the 468 GHz region with a source modulation submillimeter-wave spectrometer. The CuH molecule was generated by sputtering from copper powder in a DC glow discharge through hydrogen gas. The observed rotational transitions show the line broadening caused by the hyperfine structure due to the copper nucleus (I = 3/2). The central transition frequency, the nuclear electric quadrupole coupling constant, and the nuclear magnetic spin-rotation coupling constant were determined for each isotopomer by line-shape simulation.

Perturbation analysis for the rotational spectrum of the NiBr radical in the X2Pi3/2 and A2Delta5/2 states.

The millimeter- and submillimeter-wave spectra of the NiBr radical in the X (2)Pi(3/2) and A (2)Delta(5/2) states were observed by a source-modulated microwave spectrometer. The NiBr radical was generated in a dc glow discharge through the mixture of Br(2) vapor and Ar gas by the sputtering reaction with a Ni cathode. Observed transition frequencies were independently analyzed for both electronic states using a standard polynomial expression of a Hunds case (c) approximation. Anomalous behavior of the effective molecular constants in the X (2)Pi(3/2) state was interpreted as the result of the perturbation between the X (2)Pi(3/2) and A (2)Delta(5/2) states. The deperturbed molecular constants were derived using a simplified supermultiplet Hamiltonian including the interaction terms between the two electronic states.