skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: PHOTON-INDUCED FORMATION OF MOLECULAR HYDROGEN FROM A NEUTRAL POLYCYCLIC AROMATIC HYDROCARBON: 9,10-DIHYDROANTHRACENE

Abstract

Experimental results from infrared spectroscopy and mass spectrometry provide compelling evidence that UV irradiation of the neutral polycyclic aromatic hydrocarbon (PAH) 9,10-dihydroanthracene (DHA), trapped in solid argon (12 K), results in efficient (i.e., 90% yield) conversion to anthracene and molecular hydrogen. A number of dissociation pathways involving single or double hydrogen loss are investigated computationally. Among these, two mechanisms are most credible for a one-photon dissociation process involving UV photons <5.5 eV. For the lowest-energy pathway (2.3 eV), a simultaneous lengthening of the C-H bonds of H9 and H10 gives rise to an anthracene-H{sub 2} complex. A higher-energy mechanism (3.4 eV) involves an initial lengthening of the H9 C-H bond, followed by this hydrogen 'grabbing' H10, and forming H{sub 2}. The high yield of this photolysis reaction suggests that similar reactions may take place for other neutral PAHs, with implications for the formation of molecular hydrogen in regions of low UV exposure, such as in dark clouds.

Authors:
;
Publication Date:
OSTI Identifier:
22004343
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 744; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTROSCOPY; ANTHRACENE; ARGON; ASTROPHYSICS; HYDROGEN; INFRARED SPECTRA; MASS SPECTROSCOPY; PHOTOLYSIS; PHOTONS; POLYCYCLIC AROMATIC HYDROCARBONS

Citation Formats

Yi, Fu, Szczepanski, Jan, and Polfer, Nick C., E-mail: polfer@chem.ufl.edu. PHOTON-INDUCED FORMATION OF MOLECULAR HYDROGEN FROM A NEUTRAL POLYCYCLIC AROMATIC HYDROCARBON: 9,10-DIHYDROANTHRACENE. United States: N. p., 2012. Web. doi:10.1088/0004-637X/744/1/61.
Yi, Fu, Szczepanski, Jan, & Polfer, Nick C., E-mail: polfer@chem.ufl.edu. PHOTON-INDUCED FORMATION OF MOLECULAR HYDROGEN FROM A NEUTRAL POLYCYCLIC AROMATIC HYDROCARBON: 9,10-DIHYDROANTHRACENE. United States. https://doi.org/10.1088/0004-637X/744/1/61
Yi, Fu, Szczepanski, Jan, and Polfer, Nick C., E-mail: polfer@chem.ufl.edu. 2012. "PHOTON-INDUCED FORMATION OF MOLECULAR HYDROGEN FROM A NEUTRAL POLYCYCLIC AROMATIC HYDROCARBON: 9,10-DIHYDROANTHRACENE". United States. https://doi.org/10.1088/0004-637X/744/1/61.
@article{osti_22004343,
title = {PHOTON-INDUCED FORMATION OF MOLECULAR HYDROGEN FROM A NEUTRAL POLYCYCLIC AROMATIC HYDROCARBON: 9,10-DIHYDROANTHRACENE},
author = {Yi, Fu and Szczepanski, Jan and Polfer, Nick C., E-mail: polfer@chem.ufl.edu},
abstractNote = {Experimental results from infrared spectroscopy and mass spectrometry provide compelling evidence that UV irradiation of the neutral polycyclic aromatic hydrocarbon (PAH) 9,10-dihydroanthracene (DHA), trapped in solid argon (12 K), results in efficient (i.e., 90% yield) conversion to anthracene and molecular hydrogen. A number of dissociation pathways involving single or double hydrogen loss are investigated computationally. Among these, two mechanisms are most credible for a one-photon dissociation process involving UV photons <5.5 eV. For the lowest-energy pathway (2.3 eV), a simultaneous lengthening of the C-H bonds of H9 and H10 gives rise to an anthracene-H{sub 2} complex. A higher-energy mechanism (3.4 eV) involves an initial lengthening of the H9 C-H bond, followed by this hydrogen 'grabbing' H10, and forming H{sub 2}. The high yield of this photolysis reaction suggests that similar reactions may take place for other neutral PAHs, with implications for the formation of molecular hydrogen in regions of low UV exposure, such as in dark clouds.},
doi = {10.1088/0004-637X/744/1/61},
url = {https://www.osti.gov/biblio/22004343}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 744,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2012},
month = {Sun Jan 01 00:00:00 EST 2012}
}