Browsing by Author "Ogilvie, J. F."

Now showing 1 - 5 of 5

Absorption spectra in the vacuum ultraviolet region of methanol in condensed phases
(2007-10-15)
Kuo, Yu-Ping
;
Lu, Hsiao-Chi
;
Wu, Yu-Jong
;
Cheng, Bing-Ming
;
Ogilvie, J. F.
With radiation from a synchrotron we measured the spectra of pure solid methanol and of methanol dispersed in solid argon (molar ratio 200) and krypton (molar ratio 250) at 10 K from the onset of absorption in the vacuum ultraviolet region until the limits imposed by LiF windows or the Ar or Kr dispersant. We fitted the total absorption profile divided by wavenumber to gaussian curves of minimal number. and made tentative assignments of electronic transitions and vibrational structure by comparison with spectra of gaseous methanol and with energies and intensities from our published quantum-chemical calculations. (C) 2007 Elsevier B.V. All rights reserved.
Absorption spectra in the vacuum ultraviolet region of small molecules in condensed phases
(2008-12-15)
Lu, Hsiao-Chi
;
Chen, Hong-Kai
;
Cheng, Bing-Ming
;
Ogilvie, J. F.
;
材料科學與工程學系
With radiation from a synchrotron we measured the spectra of several small molecular species in the, solid phase at 10K, either pure -O(2), NO, CO(2), N(2)O, H(2)O and NH(3) - or, for NH3 also dispersed in Ar at, molar ratio 1/250, from the onset of absorption in the ultraviolet region until the limits of transmission by crystalline LiF or solid At. In a quantitative treatment of spectral data, we fitted the total absorption profile divided by wavenumber to Gaussian curves of minimal number, and made tentative assignments of electronic transitions and vibrational structure by comparison with spectra of gaseous species. These results illuminate the nature of electronic spectra of samples in solid phases in the vacuum ultraviolet region. (C) 2008 Elsevier B.V. All rights reserved.
Dynamics of reactions O((1)D)+C(6)H(6) and C(6)D(6)
(2008-11-07)
Chen, Hui-Fen
;
Liang, Chi-Wei
;
Lin, Jim J.
;
Lee, Yuan-Pern
;
Ogilvie, J. F.
The reaction between O((1)D) and C(6)H(6) (or C(6)D(6)) was investigated with crossed-molecular-beam reactive scattering and time-resolved Fourier-transform infrared spectroscopy. From the crossed-molecular-beam experiments, four product channels were identified. The major channel is the formation of three fragments CO+C(5)H(5)+H; the channels for formation of C(5)H(6)+CO and C(6)H(5)O+H from O((1)D)+C(6)H(6) and OD+C(6)D(5) from O((1)D)+C(6)D(6) are minor. The angular distributions for the formation of CO and H indicate a mechanism involving a long-lived collision complex. Rotationally resolved infrared emission spectra of CO (1 <=upsilon <= 6) and OH (1 <=upsilon <= 3) were recorded with a step-scan Fourier-transform spectrometer. At the earliest applicable period (0-5 mu s), CO shows a rotational distribution corresponding to a temperature of similar to 1480 K for upsilon=1 and 920-700 K for upsilon=2-6, indicating possible involvement of two reaction channels; the vibrational distribution of CO corresponds to a temperature of similar to 5800 K. OH shows a rotational distribution corresponding to a temperature of similar to 650 K for upsilon=1-3 and a vibrational temperature of similar to 4830 K. The branching ratio of [CO]/[OH]=2.1 +/- 0.4 for O((1)D)+C(6)H(6) and [CO]/[OD]>2.9 for O((1)D)+C(6)D(6) is consistent with the expectation for an abstraction reaction. The mechanism of the reaction may be understood from considering the energetics of the intermediate species and transition states calculated at the G2M(CC5) level of theory for the O((1)D)+C(6)H(6) reaction. The experimentally observed branching ratios and deuterium isotope effect are consistent with those predicted from calculations.
FORMATION AND IDENTIFICATION OF INTERSTELLAR MOLECULE LINEAR C(5)H FROM PHOTOLYSIS OF METHANE DISPERSED IN SOLID NEON
(2009-08-10)
Wu, Yu-Jong
;
Chen, Hui-Fen
;
Camacho, Cristopher
;
Witek, Henryk A.
;
Hsu, Sheng-Chuan
Photolysis of methane dispersed (1/1000) in solid Ne at 3 K with vacuum-ultraviolet light from a synchrotron produced infrared absorption lines of several products, including new lines at 3319.3 and 1955.5 cm(-1). Based on experiments with isotopic labeling and results of quantum-chemical calculations, these lines are assigned to the C-H stretching and C=C stretching modes, respectively, of interstellar molecule linear C(5)H radicals.
FORMATION AND IDENTIFICATION OF INTERSTELLAR MOLECULE LINEAR C5H FROM PHOTOLYSIS OF METHANE DISPERSED IN SOLID NEON
(2009-08-10)
Wu, Yu-Jong
;
Chen, Hui-Fen
;
Camacho, Cristopher
;
Witek, Henryk A.
;
Hsu, Sheng-Chuan
Photolysis of methane dispersed (1/1000) in solid Ne at 3 K with vacuum-ultraviolet light from a synchrotron produced infrared absorption lines of several products, including new lines at 3319.3 and 1955.5 cm(-1). Based on experiments with isotopic labeling and results of quantum-chemical calculations, these lines are assigned to the C-H stretching and C=C stretching modes, respectively, of interstellar molecule linear C5H radicals.