2018A&A...610A..65M


Query : 2018A&A...610A..65M

2018A&A...610A..65M - Astronomy and Astrophysics, volume 610A, 65-65 (2018/2-1)

High-resolution IR absorption spectroscopy of polycyclic aromatic hydrocarbons in the 3 µm region: role of hydrogenation and alkylation.

MALTSEVA E., MACKIE C.J., CANDIAN A., PETRIGNANI A., HUANG X., LEE T.J., TIELENS A.G.G.M., OOMENS J. and BUMA W.J.

Abstract (from CDS):

Aim. We aim to elucidate the spectral changes in the 3µm region that result from chemical changes in the molecular periphery of polycyclic aromatic hydrocarbons (PAHs) with extra hydrogens (H-PAHs) and methyl groups (Me-PAHs).
Methods. Advanced laser spectroscopic techniques combined with mass spectrometry were applied on supersonically cooled 1,2,3,4-tetrahydronaphthalene, 9,10-dihydroanthracene, 9,10-dihydrophenanthrene, 1,2,3,6,7,8-hexahydropyrene, 9-methylanthracene, and 9,10-dimethylanthracene, allowing us to record mass-selective and conformationally selective absorption spectra of the aromatic, aliphatic, and alkyl CH-stretches in the 3.175-3.636um region with laser-limited resolution. We compared the experimental absorption spectra with standard harmonic calculations and with second-order vibrational perturbation theory anharmonic calculations that use the SPECTRO program for treating resonances.
Results. We show that anharmonicity plays an important if not dominant role, affecting not only aromatic, but also aliphatic and alkyl CH-stretch vibrations. The experimental high-resolution data lead to the conclusion that the variation in Me- and H-PAHs composition might well account for the observed variations in the 3µm emission spectra of carbon-rich and star-forming regions. Our laboratory studies also suggest that heavily hydrogenated PAHs form a significant fraction of the carriers of IR emission in regions in which an anomalously strong 3µm plateau is observed.

Abstract Copyright: © ESO 2018

Journal keyword(s): astrochemistry - molecular data - ISM: molecules - infrared: ISM

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NGC 1333 OpC 03 29 11 +31 18.6           ~ 1337 1
2 IRAS 04296+3429 pA* 04 32 56.9743899192 +34 36 12.459816288   16.13 14.09 13.64 11.64 G0Ia 139 0
3 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 805 0
4 [D75b] Em* 21-021 PN 21 29 58.4711786760 +51 04 00.323924520   15.66 14.20 13.89   O7(f)/[WC11] 235 0
5 HD 235858 pA* 22 29 10.3748806056 +54 51 06.344572284   11.40 9.52 8.47 7.34 G5Ia 244 0

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2022.08.09-02:49:19

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