skip to main content


5 results for: All records
Author ORCID ID is 0000000244685748
Full Text and Citations
  1. The conformational preferences of pentyl- through decylbenzene are studied under jet-cooled conditions in the gas phase. Laser-induced fluorescence excitation spectra, fluorescence-dip infrared spectra in the alkyl CH stretch region, and Raman spectra are combined to provide assignments for the observed conformers. Density functional theory calculations at the B3LYP-D3BJ/def2TZVP level of theory provide relative energies and normal mode vibrations that serve as inputs for an anharmonic local mode theory introduced in earlier work on alkylbenzenes with n = 2–4. This model explicitly includes anharmonic mixing of the CH stretch modes with the overtones of scissors/bend modes of the CH 2 andmore » CH 3 groups in the alkyl chain, and is used to assign and interpret the single-conformation IR spectra. In octylbenzene, a pair of LIF transitions shifted -92 and -78 cm -1 from the all-trans electronic origin have unique alkyl CH stretch transitions that are fit by the local model to a g1g3g4 conformation in which the alkyl chain folds back over the aromatic ring π cloud. Its calculated energy is only 1.0 kJ mol -1 above the all-trans global minimum. This fold is at an alkyl chain length less than half that of the pure alkanes (n = 18), consistent with a smaller energy cost for the g1 dihedral and the increased dispersive interaction of the chain with the π cloud. Local site frequencies for the entire set of conformers from the local mode model show ‘edge effects’ that raise the site frequencies of CH 2(1) and CH 2(2) due to the phenyl ring and CH 2(n - 1) due to the methyl group. The g1g3g4 conformer also shows local sites shifted up in frequency at CH 2(3) and CH 2(6) due to interaction with the π cloud.« less

"Cited by" information provided by Web of Science.

DOE PAGES offers free public access to the best available full-text version of DOE-affiliated accepted manuscripts or articles after an administrative interval of 12 months. The portal and search engine employ a hybrid model of both centralized and distributed content, with PAGES maintaining a permanent archive of all full text and metadata.