title: Infrared spectra of ovalene (C32H14) and hydrogenated ovalene (C32H15˙) in solid para-hydrogen.
abstract: We report the infrared (IR) spectra of ovalene (C32H14) and hydrogenated ovalene (C32H15˙) in solid para-hydrogen (p-H2). The hydrogenated ovalene and protonated ovalene were generated from electron bombardment of a mixture of ovalene and p-H2during deposition of a matrix at 3.2 K. The features that decreased with time have been previously assigned to 7-C32H15+, the most stable isomer of protonated ovalene (Astrophys. J., 2016, 825, 96). The spectral features that increased with time are assigned to the most stable isomer of hydrogenated ovalene (7-C32H15˙) based on the expected chemistry and on a comparison with the vibrational wavenumbers and IR intensities predicted by the B3PW91/6-311++G(2d,2p) method. The mechanism of formation of 7-C32H15˙ is discussed according to the observed changes in intensity and calculated energetics of possible reactions of H + C32H14and isomerization of C32H15˙. The formation of 7-C32H15˙ is dominated by the reaction H + C32H14→ 7-C32H15˙, implying that, regardless of the presence of a barrier, the hydrogenation of polycyclic aromatic hydrocarbons occurs even at 3.2 K.
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Sciences, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan. tsuge@nctu.edu.tw yplee@mail.nctu.edu.tw.
authors.forename: Masashi
authors.identifier: http://orcid.org/0000-0001-9669-1288
authors.initials: M
authors.lastname: Tsuge
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Sciences, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan. tsuge@nctu.edu.tw yplee@mail.nctu.edu.tw.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Bahou
authors.affiliation: National Synchrotron Radiation Research Center, 101, Hsin-Ann Road, Hsinchu 30076, Taiwan.
authors.forename: Yu-Jong
authors.initials: YJ
authors.lastname: Wu
authors.affiliation: The Astrophysics and Astrochemistry Laboratory, NASA Ames Research Center, Moffett Field, CA 94035, USA.
authors.forename: Louis
authors.initials: L
authors.lastname: Allamandola
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Sciences, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan. tsuge@nctu.edu.tw yplee@mail.nctu.edu.tw and Institute of Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: Yuan-Pern
authors.identifier: http://orcid.org/0000-0001-6418-7378
authors.initials: YP
authors.lastname: Lee