Photoionization and Ensuing Ion-Molecule Reactions of Polycyclic Aromatic Hydrocarbons in Alkane and Alcohol Solutions

Journal Article · Thu Apr 15 04:00:00 EDT 1993 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100117a027· OSTI ID:6043631

Liu, A; Loffredo, D M; Trifunac, A D ^[1]

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1. Argonne National Lab., IL (United States)

A common reaction pathway involving ion-molecule reactions of excited ions in indicated for a series of polycyclic aromatic hydrocarbons photoionized using intense pulsed excimer lasers (248 and 308 nm). The overall yields of free electrons and free aromatic radical cations created by two-photon ionization are measured by laser flash photolysis in cyclohexane and in 2-propanel solutions. The electron yields increase with increasing photon energies and photon flux, but the yield of radical cation is found to decrease with increasing photon flux. Photoproducts derived from aryl and solvent radicals are observed and quantified by GC and GC-MS, and their yields increase with increasing photon energy and photon flux. The diminished yield of radical ions at higher photon flux suggests an alternate higher energy reaction pathway for the radical cation. While aryl radical cations are relatively unreactive, an excited aryl radical cation could protonate the surrounding solvent, leading to aryl radical formation (AH[sup [center dot]+*] + RH [yields] A[sup [center dot]] + RH[sub 2][sup +]). Solvent radical formation would then result from hydrogen atom abstraction by aryl radicals. Product studies support this ion-molecule reaction pathway and exclude alternate mechanisms involving neutral excited state homolysis. 22 refs., 13 figs., 4 tabs.

• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6043631
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 97:15; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ALCOHOLS
ALKANES
AROMATICS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DISPERSIONS
EXPERIMENTAL DATA
HYDROCARBONS
HYDROXY COMPOUNDS
INFORMATION
IONIZATION
KINETICS
MIXTURES
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOIONIZATION
POLYCYCLIC AROMATIC HYDROCARBONS
RADICALS
REACTION KINETICS
SOLUTIONS
SOLVENTS