Laboratory Gas-phase Infrared Spectra of Two Astronomically Relevant PAH Cations: Diindenoperylene, C32H16+ and Dicoronylene, C48H20+

被引：29
作者：
Zhen, Junfeng [1 ,2 ,3 ,4 ]
Candian, Alessandra [1 ]
Castellanos, Pablo [1 ,2 ]
Bouwman, Jordy [2 ,5 ]
Linnartz, Harold [2 ]
Tielens, Alexander G. G. M. [1 ]
机构：
[1] Leiden Univ, Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands
[2] Leiden Univ, Leiden Observ, Sackler Lab Astrophys, POB 9513, NL-2300 RA Leiden, Netherlands
[3] Univ Sci & Technol China, Dept Astron, CAS Key Lab Res Galaxies & Cosmol, Hefei 230026, Anhui, Peoples R China
[4] Univ Sci & Technol China, Sch Astron & Space Sci, Hefei 230026, Anhui, Peoples R China
[5] Radboud Univ Nijmegen, Inst Mol & Mat, FELIX Lab, Toernooiveld 7C, NL-6525 ED Nijmegen, Netherlands
来源：
ASTROPHYSICAL JOURNAL | 2018年 / 854卷 / 01期
基金：
美国国家科学基金会; 欧洲研究理事会;
关键词：
astrochemistry; ISM: abundances; ISM: molecules; molecular data; molecular processes; POLYCYCLIC AROMATIC-HYDROCARBON; HEXA-PERI-HEXABENZOCORONENE; SPITZER-SPACE-TELESCOPE; EMISSION SPECTROSCOPY; INTERSTELLAR-MEDIUM; MOLECULES; BANDS; PHOTODISSOCIATION; NAPHTHALENE; CORONENE;
D O I：
10.3847/1538-4357/aaa7f2
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
The first gas-phase infrared spectra of two isolated astronomically relevant and large polycyclic aromatic hydrocarbon (PAH) cations-diindenoperylene (DIP) and dicoronylene (DC)-in the 530-1800 cm(-1) (18.9-5.6 mu m) range-are presented. Vibrational band positions are determined for comparison to the aromatic infrared bands. The spectra are obtained via infrared multiphoton dissociation spectroscopy of ions stored in a quadrupole ion trap using the intense and tunable radiation of the free electron laser for infrared experiments (FELIX). DIP+ shows its main absorption peaks at 737 (13.57), 800 (12.50), 1001 (9.99), 1070 (9.35), 1115 (8.97), 1152 (8.68), 1278 (7.83), 1420 (7.04), and 1550 (6.45) cm(-1)(mu m), in good agreement with density functional theory (DFT) calculations that are uniformly scaled to take anharmonicities into account. DC+ has its main absorption peaks at 853 (11.72), 876 (11.42), 1032 (9.69), 1168 (8.56), 1300 (7.69), 1427 (7.01), and 1566 (6.39) cm(-1)(mu m), which also agree well with the scaled DFT results presented here. The DIP+ and DC+ spectra are compared with the prominent infrared features observed toward NGC 7023. This results both in matches and clear deviations. Moreover, in the 11.0-14.0 mu m region, specific bands can be linked to CH out-of-plane (oop) bending modes of different CH edge structures in large PAHs. The molecular origin of these findings and their astronomical relevance are discussed.
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