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Physical Sciences and Mathematics

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Berwyck L. J. Poad

Spectra

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Full-Text Articles in Social and Behavioral Sciences

Infrared Spectra Of The Li +_(H 2)N(N=1-3) Cation Complexes, C Emmeluth, B L. J Poad, C D. Thompson, G H. Weddle, E J. Bieske May 2013

Infrared Spectra Of The Li +_(H 2)N(N=1-3) Cation Complexes, C Emmeluth, B L. J Poad, C D. Thompson, G H. Weddle, E J. Bieske

Berwyck L. J. Poad

The Li+–(H2)n n = 1–3 complexes are investigated through infrared spectra recorded in the H–H stretch region (3980–4120 cm−1) and through ab initio calculations at the MP2∕aug-cc-pVQZ level. The rotationally resolved H–H stretch band of Li+–H2 is centered at 4053.4 cm−1 [a −108 cm−1 shift from the Q1(0) transition of H2]. The spectrum exhibits rotational substructure consistent with the complex possessing a T-shaped equilibrium geometry, with the Li+ ion attached to a slightly perturbed H2 molecule. Around 100 rovibrational transitions belonging to parallel Ka = 0‐0, 1-1, 2-2, and 3-3 subbands are observed. The Ka = 0‐0 and 1-1 transitions …


Interactions Between The Chloride Anion And Aromatic Molecules: Infrared Spectra Of The Cl-_C6h5ch3, Cl-_C6h5nh2 And Cl-_C6h5oh Complexes, Corinna Emmeluth, Berwyck L. J Poad, Christopher D. Thompson, Evan J. Bieske May 2013

Interactions Between The Chloride Anion And Aromatic Molecules: Infrared Spectra Of The Cl-_C6h5ch3, Cl-_C6h5nh2 And Cl-_C6h5oh Complexes, Corinna Emmeluth, Berwyck L. J Poad, Christopher D. Thompson, Evan J. Bieske

Berwyck L. J. Poad

The Cl-−C6H5CH3·Ar, Cl-−C6H5NH2·Ar, and Cl-−C6H5OH·Ar anion complexes are investigated using infrared photodissociation spectroscopy and ab initio calculations at the MP2/aug-cc-pVDZ level. The results indicate that for Cl-−C6H5NH2 and Cl-−C6H5OH, the Cl- anion is attached to the substituent group by a single near-linear hydrogen bond. For Cl-−C6H5CH3, the Cl- is attached to an ortho-hydrogen atom on the aromatic ring and to a hydrogen atom on the methyl group by a weaker hydrogen bond. The principal spectroscopic consequence of the hydrogen-bonding interaction in the three complexes is a red-shift and intensity increase for the CH, NH, and OH stretching modes. Complexities in …


Infrared Spectra Of Mass-Selected Al+_(Ch4)Nn=1-6clusters, B Poad, C Thompson, E Bieske May 2013

Infrared Spectra Of Mass-Selected Al+_(Ch4)Nn=1-6clusters, B Poad, C Thompson, E Bieske

Berwyck L. J. Poad

Infrared spectra are recorded for Al+–(CH4)n n = 1–6 clusters in the CH stretch region (2800–3100 cm−1). The spectra, which are obtained by monitoring photofragmentation in a tandem mass spectrometer, are dominated by a single, narrow band corresponding to the totally symmetric C–H stretching mode of the CH4 subunits (rendered infrared active through the interaction with the Al+ cation). This band shifts progressively to higher wavenumber as the clusters becomes larger, concomitant with a weakening of the intermolecular Al+⋯CH4 bonds. Supporting ab initio calculations for the n = …


Mixing Laser Spectroscopy And Mass Spectrometry- Infrared Spectra Of Metal Cation- Hydrogen Complexes, Vikoras Dryza, Berwyck Poad, Evan Bieske May 2013

Mixing Laser Spectroscopy And Mass Spectrometry- Infrared Spectra Of Metal Cation- Hydrogen Complexes, Vikoras Dryza, Berwyck Poad, Evan Bieske

Berwyck L. J. Poad

We describe recent experiments in which mass spectrometry and laser spectroscopy are combined to characterize Li(+)-H(2), Na(+)-H(2), B(+)-H(2), and Al(+)-H(2) complexes in the gas-phase. The infrared spectra, which feature full resolution of rotational sub-structure, are recorded by monitoring M(+) photo fragments as the infrared wavelength is scanned. The spectra deliver detailed information on the way in which a hydrogen molecule is attached to a metal cation including the intermolecular separation, the force constant for the intermolecular bond and the H-H stretching frequency. The complexes all possess T-shaped equilibrium geometries and display a clear correlation between the length and force constant …


Infrared Spectra Of Cl-_(C6h6)Mm=1, 2, Christopher Thompson, Berwyck Poad, Corinna Emmeluth, Evan Bieske May 2013

Infrared Spectra Of Cl-_(C6h6)Mm=1, 2, Christopher Thompson, Berwyck Poad, Corinna Emmeluth, Evan Bieske

Berwyck L. J. Poad

The Cl--(C6H6)Arn n = 0,1,2 and Cl--(C6H6)2 complexes are investigated using photodissociation infrared spectroscopy in the CH stretch region and through ab initio calculations at the MP2/aug-cc-pVDZ level. The results indicate that Cl--C6H6 possesses a planar structure in which the benzene molecule is attached to the Cl- anion by a double hydrogen bond. The calculations predict that Cl (C6H6)2 has a C2 symmetry structure in which the two face-to-face benzene molecules are attached to …


Infrared Spectra Of Mass-Selected Mg+-H2 And Mg +-D2 Complexes, Viktoras Dryza, Berwyck L. Poad, Evan J. Bieske May 2013

Infrared Spectra Of Mass-Selected Mg+-H2 And Mg +-D2 Complexes, Viktoras Dryza, Berwyck L. Poad, Evan J. Bieske

Berwyck L. J. Poad

Rotationally resolved infrared spectra of Mg(+)-H(2) and Mg(+)-D(2) are recorded in the H-H (4025-4080 cm(-1)) and D-D (2895-2945 cm(-1)) stretch regions by monitoring Mg(+) photofragments. The nu(HH) and nu(DD) transitions of Mg(+)-H(2) and Mg(+)-D(2) are red-shifted by 106.2 +/- 1.5 and 76.0 +/- 0.1 cm(-1) respectively from the fundamental vibrational transitions of the free H(2) and D(2) molecules. The spectra are consistent with a T-shaped equilibrium structure in which the Mg(+) ion interacts with a slightly perturbed H(2) or D(2) molecule. From the spectroscopic constants, a vibrationally averaged intermolecular separation of 2.716 A (2.687 A) is deduced for the ground …