The Experts below are selected from a list of 117 Experts worldwide ranked by ideXlab platform
James R. Durig - One of the best experts on this subject based on the ideXlab platform.
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Far infrared Spectrum, barrier to internal rotation, and ab initio calculations for 3,3,3-trifluoropropene
Vibrational Spectroscopy, 2000Co-Authors: Gamil A. Guirgis, Huimin Zhen, J.b. Robb, James R. DurigAbstract:Abstract The far infrared Spectrum of gaseous 3,3,3-trifluoropropene, CH 2 CHCF 3 , between 350 and 30 cm −1 has been recorded at a resolution of 0.10 cm −1 . The torsional fundamental for the CF 3 rotor is observed at 83.52 cm −1 . There are three and possibly four “hot bands”, which accompany this fundamental falling to lower wavenumbers with decreasing intensities. Utilizing these torsional data along with structural parameters obtained from MP2/6-311+G** ab initio calculations to calculate the kinetic constant F , the barrier to internal rotation has been determined to be 630±10 cm −1 (7.54±0.12 kJ/mol) and the V 6 term is relatively small with a value of −30±5 cm −1 (−0.36±0.06 kJ/mol). These results are compared to the CH 3 barrier of propene as well as to those of several CF 3 rotors. The harmonic force fields, infrared intensities, Raman activities, and depolarization ratios have been obtained from both ab initio RHF/6-31G* and MP2/6-31G* calculations and the results compared. Additionally, predicted quantities are compared to the corresponding experimental values when appropriate as well as with some corresponding results for some similar molecules.
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Far-Infrared Spectrum, ab Initio, and DFT Calculations and Two-Dimensional Torsional Potential Function of Dimethylallene (3-Methyl-1,2-butadiene)
The Journal of Physical Chemistry A, 2000Co-Authors: Stephen Bell, Peter Groner, And Gamil A. Guirgis, James R. DurigAbstract:The Far-Infrared and infrared spectra of gaseous dimethylallene (3-methyl-1,2-butadiene), (CH3)2CCCH2, were measured as well as the Raman spectra of the compound in all three physical phases. The spectra were assigned using infrared band contours, Raman depolarization ratios and ab initio predicted harmonic frequencies and intensities as criteria. The torsional energy level splittings were determined for the ground state and one torsional excited state from previously published microwave spectra by fitting the frequencies to an effective rotational Hamiltonian for molecules with two periodic large-amplitude motions. The splittings and the data from the Far-Infrared Spectrum were used to derive the two-dimensional torsional potential function of dimethylallene. This function with an effective barrier V3eff = 726(4) cm-1 is compared with the results from the microwave analysis and with the potential function calculated by a number of ab initio methods (among them B3LYP/6-31G(d) and MP2/DZ(d)).
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Far Infrared Spectrum, ab Initio Calculations, and Conformational Analysis of 1-Pentyne
The Journal of Physical Chemistry A, 1997Co-Authors: Stephen Bell, Gamil A. Guirgis, James R. DurigAbstract:The far infrared Spectrum of 1-pentyne, CH3CH2CH2C⋮CH, has been recorded in the gas phase. The fundamental asymmetric torsional transitions have been observed at 114 and 109 cm-1 for the gauche (synclinal) and trans (antiperiplanar; methyl group trans to the acetylenic group) conformers, respectively. The methyl torsional fundamental (249.8 cm-1) has only been observed for the gauche conformer. Infrared spectra (3500−400 cm-1) of 1-pentyne dissolved in liquid xenon have been recorded from which variable temperature (−60 to −100 °C) studies have been carried out. From these data, the enthalpy difference has been determined to be 113 ± 26 cm-1 (323 ± 74 cal/mol) with the trans conformer more stable than the gauche form. The Raman Spectrum (3500−40 cm-1) has also been recorded of the liquid to aid in the assignment of the fundamentals. Ab initio electronic structure calculations of energies, conformational geometries, vibrational frequencies, and potential energy functions have been carried out to complement...
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Far-Infrared Spectrum and barriers to internal rotation of propanal
8th Intl Conf on Fourier Transform Spectroscopy, 1992Co-Authors: Gamil A. Guirgis, W. E. Brewer, Jian Liu, Stephen Bell, James R. DurigAbstract:The Far-Infrared Spectrum has been recorded from 50 to 360 cm-1 at a resolution of 0.10 cm-1 for propanol, CH3CH2CHO, as well as for three additional isotopic species, CH3CH2CDO, CH3CD2CHO, and CD3CD2CHO. The fundamental methyl torsional transitions have been observed for both the s-cis and gauche conformers for all four isotopic species from which the threefold barriers to internal rotation have been calculated. For the gauche conformer V3 equals 1040 +/- 50 cm-1 and V6 equals 23 +/- 11 cm-1, and for the s-cis conformer V3 equals 850 +/- 50 cm-1. The asymmetric torsional transitions for each isotopic species have also been assigned, and the potential function governing the internal rotation of the CHO rotor has been determined. The data include significant coupling between the symmetric and asymmetric rotors.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Chunrui Wang - One of the best experts on this subject based on the ideXlab platform.
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Raman scattering, far infrared Spectrum of BiI3 nanocrystallites
Materials Letters, 2003Co-Authors: Yijun Yang, Chunrui Wang, Junqing Hou, Jianming DaiAbstract:Abstract The optical properties of BiI 3 nanocrystallites have been investigated by Raman scattering, far infrared Spectrum and UV–vis absorption at room temperature. The Raman and far infrared Spectrum of the BiI 3 nanocrystallites have a shift in comparison with that of the BiI 3 single crystals. The shift is mainly attributed to nanosize effect. The first exciton peak of BiI 3 nanocrystallites is a slight blue shift in comparison with the band gap of the bulk materials.
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Raman scattering, far infrared Spectrum and photoluminescence of SnS2 nanocrystallites
Chemical Physics Letters, 2002Co-Authors: Chunrui Wang, Kaibin Tang, Qing Yang, Yitai QianAbstract:Abstract The optical property of SnS2 nanocrystallites has been investigated by Raman scattering, far infrared Spectrum and photoluminescence at room temperature. The Raman and far infrared Spectrum of the SnS2 nanocrystallites have a shift in comparison with that of the SnS2 single crystals. The shift is mainly attributed to nanosize effect. The intralayer and interlayer force constant of SnS2 nanocrystallites have been calculated by using a linear chain model. The photoluminescence of SnS2 nanocrystallites is reported for the first time.
Stephen Bell - One of the best experts on this subject based on the ideXlab platform.
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Far-Infrared Spectrum, ab Initio, and DFT Calculations and Two-Dimensional Torsional Potential Function of Dimethylallene (3-Methyl-1,2-butadiene)
The Journal of Physical Chemistry A, 2000Co-Authors: Stephen Bell, Peter Groner, And Gamil A. Guirgis, James R. DurigAbstract:The Far-Infrared and infrared spectra of gaseous dimethylallene (3-methyl-1,2-butadiene), (CH3)2CCCH2, were measured as well as the Raman spectra of the compound in all three physical phases. The spectra were assigned using infrared band contours, Raman depolarization ratios and ab initio predicted harmonic frequencies and intensities as criteria. The torsional energy level splittings were determined for the ground state and one torsional excited state from previously published microwave spectra by fitting the frequencies to an effective rotational Hamiltonian for molecules with two periodic large-amplitude motions. The splittings and the data from the Far-Infrared Spectrum were used to derive the two-dimensional torsional potential function of dimethylallene. This function with an effective barrier V3eff = 726(4) cm-1 is compared with the results from the microwave analysis and with the potential function calculated by a number of ab initio methods (among them B3LYP/6-31G(d) and MP2/DZ(d)).
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Far Infrared Spectrum, ab Initio Calculations, and Conformational Analysis of 1-Pentyne
The Journal of Physical Chemistry A, 1997Co-Authors: Stephen Bell, Gamil A. Guirgis, James R. DurigAbstract:The far infrared Spectrum of 1-pentyne, CH3CH2CH2C⋮CH, has been recorded in the gas phase. The fundamental asymmetric torsional transitions have been observed at 114 and 109 cm-1 for the gauche (synclinal) and trans (antiperiplanar; methyl group trans to the acetylenic group) conformers, respectively. The methyl torsional fundamental (249.8 cm-1) has only been observed for the gauche conformer. Infrared spectra (3500−400 cm-1) of 1-pentyne dissolved in liquid xenon have been recorded from which variable temperature (−60 to −100 °C) studies have been carried out. From these data, the enthalpy difference has been determined to be 113 ± 26 cm-1 (323 ± 74 cal/mol) with the trans conformer more stable than the gauche form. The Raman Spectrum (3500−40 cm-1) has also been recorded of the liquid to aid in the assignment of the fundamentals. Ab initio electronic structure calculations of energies, conformational geometries, vibrational frequencies, and potential energy functions have been carried out to complement...
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Far-Infrared Spectrum and barriers to internal rotation of propanal
8th Intl Conf on Fourier Transform Spectroscopy, 1992Co-Authors: Gamil A. Guirgis, W. E. Brewer, Jian Liu, Stephen Bell, James R. DurigAbstract:The Far-Infrared Spectrum has been recorded from 50 to 360 cm-1 at a resolution of 0.10 cm-1 for propanol, CH3CH2CHO, as well as for three additional isotopic species, CH3CH2CDO, CH3CD2CHO, and CD3CD2CHO. The fundamental methyl torsional transitions have been observed for both the s-cis and gauche conformers for all four isotopic species from which the threefold barriers to internal rotation have been calculated. For the gauche conformer V3 equals 1040 +/- 50 cm-1 and V6 equals 23 +/- 11 cm-1, and for the s-cis conformer V3 equals 850 +/- 50 cm-1. The asymmetric torsional transitions for each isotopic species have also been assigned, and the potential function governing the internal rotation of the CHO rotor has been determined. The data include significant coupling between the symmetric and asymmetric rotors.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Gamil A. Guirgis - One of the best experts on this subject based on the ideXlab platform.
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Far infrared Spectrum, barrier to internal rotation, and ab initio calculations for 3,3,3-trifluoropropene
Vibrational Spectroscopy, 2000Co-Authors: Gamil A. Guirgis, Huimin Zhen, J.b. Robb, James R. DurigAbstract:Abstract The far infrared Spectrum of gaseous 3,3,3-trifluoropropene, CH 2 CHCF 3 , between 350 and 30 cm −1 has been recorded at a resolution of 0.10 cm −1 . The torsional fundamental for the CF 3 rotor is observed at 83.52 cm −1 . There are three and possibly four “hot bands”, which accompany this fundamental falling to lower wavenumbers with decreasing intensities. Utilizing these torsional data along with structural parameters obtained from MP2/6-311+G** ab initio calculations to calculate the kinetic constant F , the barrier to internal rotation has been determined to be 630±10 cm −1 (7.54±0.12 kJ/mol) and the V 6 term is relatively small with a value of −30±5 cm −1 (−0.36±0.06 kJ/mol). These results are compared to the CH 3 barrier of propene as well as to those of several CF 3 rotors. The harmonic force fields, infrared intensities, Raman activities, and depolarization ratios have been obtained from both ab initio RHF/6-31G* and MP2/6-31G* calculations and the results compared. Additionally, predicted quantities are compared to the corresponding experimental values when appropriate as well as with some corresponding results for some similar molecules.
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far infrared Spectrum ab initio calculations conformational energy differences barriers to internal rotation and r0 structure of propanal
Journal of Physical Chemistry A, 1997Co-Authors: J. R. Durig, Gamil A. Guirgis, And Stephen Bell, W. E. BrewerAbstract:The Far-Infrared Spectrum has been recorded from 50 to 360 cm-1 at a resolution of 0.10 cm-1 for normal propanal CH3CH2CHO and for the three isotopic species CH3CH2CDO, CH3CD2CHO, and CD3CD2CHO. Along with the fundamental asymmetric torsional transition, several hot band transitions of the cis conformer have been observed and assigned for each isotopic species. The geometrical structures of the cis and gauche conformers have been determined by ab initio calculations in order to compare them with previously reported microwave structures and to calculate inertial constants for the two internal rotations. A wide range of basis sets and ab initio theoretical methods up to MP4 have been used in order to determine the cis to gauche conformational energy difference. Using both the observed and calculated data, along with the previously reported gauche dihedral angle and microwave splittings for the gauche ground state for the CH3CH2CHO and CH3CH2CDO molecules, the asymmetric torsional potential function has been...
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Far Infrared Spectrum, ab Initio Calculations, and Conformational Analysis of 1-Pentyne
The Journal of Physical Chemistry A, 1997Co-Authors: Stephen Bell, Gamil A. Guirgis, James R. DurigAbstract:The far infrared Spectrum of 1-pentyne, CH3CH2CH2C⋮CH, has been recorded in the gas phase. The fundamental asymmetric torsional transitions have been observed at 114 and 109 cm-1 for the gauche (synclinal) and trans (antiperiplanar; methyl group trans to the acetylenic group) conformers, respectively. The methyl torsional fundamental (249.8 cm-1) has only been observed for the gauche conformer. Infrared spectra (3500−400 cm-1) of 1-pentyne dissolved in liquid xenon have been recorded from which variable temperature (−60 to −100 °C) studies have been carried out. From these data, the enthalpy difference has been determined to be 113 ± 26 cm-1 (323 ± 74 cal/mol) with the trans conformer more stable than the gauche form. The Raman Spectrum (3500−40 cm-1) has also been recorded of the liquid to aid in the assignment of the fundamentals. Ab initio electronic structure calculations of energies, conformational geometries, vibrational frequencies, and potential energy functions have been carried out to complement...
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Far-Infrared Spectrum and barriers to internal rotation of propanal
8th Intl Conf on Fourier Transform Spectroscopy, 1992Co-Authors: Gamil A. Guirgis, W. E. Brewer, Jian Liu, Stephen Bell, James R. DurigAbstract:The Far-Infrared Spectrum has been recorded from 50 to 360 cm-1 at a resolution of 0.10 cm-1 for propanol, CH3CH2CHO, as well as for three additional isotopic species, CH3CH2CDO, CH3CD2CHO, and CD3CD2CHO. The fundamental methyl torsional transitions have been observed for both the s-cis and gauche conformers for all four isotopic species from which the threefold barriers to internal rotation have been calculated. For the gauche conformer V3 equals 1040 +/- 50 cm-1 and V6 equals 23 +/- 11 cm-1, and for the s-cis conformer V3 equals 850 +/- 50 cm-1. The asymmetric torsional transitions for each isotopic species have also been assigned, and the potential function governing the internal rotation of the CHO rotor has been determined. The data include significant coupling between the symmetric and asymmetric rotors.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Jianming Dai - One of the best experts on this subject based on the ideXlab platform.
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Raman scattering, far infrared Spectrum of BiI3 nanocrystallites
Materials Letters, 2003Co-Authors: Yijun Yang, Chunrui Wang, Junqing Hou, Jianming DaiAbstract:Abstract The optical properties of BiI 3 nanocrystallites have been investigated by Raman scattering, far infrared Spectrum and UV–vis absorption at room temperature. The Raman and far infrared Spectrum of the BiI 3 nanocrystallites have a shift in comparison with that of the BiI 3 single crystals. The shift is mainly attributed to nanosize effect. The first exciton peak of BiI 3 nanocrystallites is a slight blue shift in comparison with the band gap of the bulk materials.
