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Title: High resolution spectroscopy of jet cooled phenyl radical: The ν 1 and ν 2 a 1 symmetry C–H stretching modes

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 145; Journal Issue: 4; Related Information: CHORUS Timestamp: 2016-12-27 20:32:23; Journal ID: ISSN 0021-9606
American Institute of Physics
Country of Publication:
United States

Citation Formats

Chang, Chih-Hsuan, and Nesbitt, David J. High resolution spectroscopy of jet cooled phenyl radical: The ν 1 and ν 2 a 1 symmetry C–H stretching modes. United States: N. p., 2016. Web. doi:10.1063/1.4955295.
Chang, Chih-Hsuan, & Nesbitt, David J. High resolution spectroscopy of jet cooled phenyl radical: The ν 1 and ν 2 a 1 symmetry C–H stretching modes. United States. doi:10.1063/1.4955295.
Chang, Chih-Hsuan, and Nesbitt, David J. 2016. "High resolution spectroscopy of jet cooled phenyl radical: The ν 1 and ν 2 a 1 symmetry C–H stretching modes". United States. doi:10.1063/1.4955295.
title = {High resolution spectroscopy of jet cooled phenyl radical: The ν 1 and ν 2 a 1 symmetry C–H stretching modes},
author = {Chang, Chih-Hsuan and Nesbitt, David J.},
abstractNote = {},
doi = {10.1063/1.4955295},
journal = {Journal of Chemical Physics},
number = 4,
volume = 145,
place = {United States},
year = 2016,
month = 7

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4955295

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  • The 3/ bands of /sup 187/Os/sup 16/O/sub 4/, /sup 189/Os/sup 16/O/sub 4/, and /sup 192/Os/sup 16/O/sub 4/ have been recorded using both a Michelson interferometer (resolution 0.06 cm/sup -1/) and a tunable semiconductor diode laser (resolution limited by the Doppler width, approx.0.0007 cm/sup -1/). The rotational fine structure differs from that of most other spherical-top molecules, for only rotational levels of A symmetry exist. A total of 112 individual vibration--rotation lines in the P and R branches of the three isotopic species were calibrated against stimulated emission lines from a high-voltage CO/sub 2/ gain cell, and were used tomore » determine three scalar and two tensor spectroscopic constants for each species; an additional scalar constant was obtained from an analysis of the Q branch of /sup 192/OsO/sub 4/. The strength of P (11) A/sub 2//sup ts0/ was measured for /sup 192/OsO/sub 4/ and yields a vibrational transition moment for 3/ of 0.17 +- 0.02 D. Transitions of all isotopic species that are expected to fall near CO/sub 2/ laser lines in the region 949--972 cm/sup -1/ are tabulated as an aid in the interpreation of saturation spectroscopy experiments. The general quadratic symmetry and valence force constants of OsO/sub 4/ were redetermined, using the isotope shifts in 3/ as the additional constraints for the F/sub 2/ symmetry block.« less
  • The {ital {tilde A}}({sup 1}{ital B}{sub 1}){l_arrow}{ital {tilde X}}({sup 1}{ital A}{sub 1}) electronic transition of difluorocarbene (CF{sub 2}) has been studied by laser-induced fluorescence spectroscopy in a supersonic free jet and by {ital ab} {ital initio} theoretical methods. The radical was formed by pyrolysis of C{sub 2}F{sub 4} at {similar_to}1000 {degree}C with a heating chamber at the tip of the nozzle just prior to the gas expansion. Fairly complete rotational cooling, but incomplete vibrational cooling allowed the identification of several new hot band transitions. {ital Ab} {ital initio} calculations for the {ital {tilde X}}({sup 1}{ital A}{sub 1}), {ital {tilde a}}({supmore » 3}{ital B}{sub 1}), and {ital {tilde A}}({sup 1}{ital B}{sub 1}) electronic states were performed using the CASSCF method in conjunction with Dunning`s cc-pVTZ basis set, as well as two smaller sets. The calculations allow us to distinguish between several possible assignments of the observed transitions, and hence determine the vibrational frequencies of the two previously unassigned {ital {tilde A}}-state stretching frequencies: {nu}{sub 3}{sup {prime}}=1180{plus_minus}2 cm{sup {minus}1} and {nu}{sub 1}{sup {prime}}=1011{plus_minus}2 cm{sup {minus}1}. The ordering of these modes is different from that in the ground state ({nu}{sub 1}{sup {double_prime}}{gt}{nu}{sub 3}{sup {double_prime}}) and mechanisms for the switching are discussed.« less
  • Detailed ESR studies are reported for the acetaldehyde radical cation (CH/sub 3/CHO/sup +/) trapped in neon matrices. The cation was generated by photoionization, electron bombardment, or laser multiphoton ionization of dilute acetaldehyde neon mixtures (10/sup 2/ to 10/sup 4/ dilution factor) during codeposition on a flat target at 4 K. Its ESR spectrum was well resolved and showed strong preferential orientation effects, two sets of strong features being observed for field directions in the target plane, while another set of weaker line components became strongly enhanced when the field was applied normal to this plane. These results indicate that themore » cations are aligned with their CCHO planes parallel to the deposition surface. Accordingly, the largest principal value of the g tensor is found to perpendicular to the CCHO plane, as previously determined for the formaldehyde cation (H/sub 2/CO/sup +/). The measured values of the g and aldehydic /sup 1/H hyperfine tensors are consistent with the assignment of the unpaired electron to the nonbonding oxygen-centered 10a' molecular orbital which is, however, about 50% delocalized onto the aldehydic hydrogen (1s) and methyl carbon (2p) orbitals. The g and aldehydic /sup 1/H A tensor components are the following: g/sub x/ = 2.0069 (3), A/sub x/ = 355 (1) MHz; g/sub z/ = 2.0019 (6), A/sub z/ = 374 (3) MHz, g/sub y/ = 2.0026 (3), A/sub y/ = 353 (1) MHz. The much smaller hyperfine interaction (4.3 MHz) with the hydrogens of the methyl group is exceedingly well resolved into a 1:1:1:1 quartet at 4 K with the field normal to the CCHO plane. In contrast to the neon studies, the ESR spectra of the acetaldehyde radical cation in Freon matrices show much poorer resolution and are complicated by the appearance of a highly structures anisotropic /sup 35/Cl hyperfine interaction below 120 K.« less
  • A detailed study of the umbrellalike vibration in inner-shell spectroscopy is presented. The high-resolution x-ray absorption spectrum for the lowest lying core excitation of the CH{sub 3} free radical was recorded. High quality potential energy surfaces (PES) for the initial and final states of the transition were calculated as a function of the symmetrical stretching and the umbrella deformation coordinates. The strong anharmonicity along the umbrella coordinate in the double-well region of the PES of the core excited state has a strong effect on the bending vibrational progressions. The excellent agreement between the experiment and theory allows an accurate spectroscopicmore » characterization of the vibrational structure of the electronic transition, and the estimation of the umbrella inversion time of 149 fs.« less