Matrix effects on the charge resonance energy of the dimer cations. Low- temperature radiolysis of glassy aromatic solutions

Journal Article · Thu Sep 25 04:00:00 EDT 1975 · J. Phys. Chem., v. 79, no. 20, pp. 2098-2105

DOI:https://doi.org/10.1021/j100587a006· OSTI ID:4146396

Buhler, R E; Funk, W

Near-infrared absorption bands due to several aromatic hydrocarbons in irradiated organic glasses were assigned to the charge resonance band of the corresponding dimer cations. The observed drastic changes of these bands with the matrix characteristics were found to correspond to the changes in the structure of the dimer cation: a hard matrix (e.g., methylcyclohexane) strongly distorts the dimer cation, thereby reducing the charge resonance energy, unless steric effects are involved (difference between benzene and tert-butylbenzene). On softening the matrix there is a continuous relaxation process with a simultaneous increase in the charge resonance energy, until the conformation of the free dimer cation is reached. It is concluded that benzene and tert- butylbenzene do form quite loose complexes, suffering large matrix effects, that the naphthalene dimer cation is a very tight complex with no matrix effects, and that bromobenzene is intermediate. Earlier published band assignments by Ekstrom for systems with benzene are reconsidered in the context of this matrix effects. For a 3MP glass with benzene and CCl$sub 3$Br the benzene dimer cation decays isothermally (77$sup 0$K) into a new transient, absorbing at 740 nm. The corresponding changes in the absorptions cannot be related to a matrix effect. The new 740-nm band was tentatively assigned to a complex between the benzene cation and CCl$sub 3$Br. The decay of the bromobenzene dimer cation in 3MP leads to the formation of a new absorption at 570 nm. This is assigned to the (Br- BrPh) charge transfer complex. (auth)

• Research Organization: Swiss Federal Inst. of Tech., Zurich
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-000124
• OSTI ID: 4146396
• Journal Information: J. Phys. Chem., v. 79, no. 20, pp. 2098-2105, Journal Name: J. Phys. Chem., v. 79, no. 20, pp. 2098-2105; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

*AROMATICS-- RADIOLYSIS
*BIPHENYL-- RADIOLYSIS
*CYCLOALKANES-- RADIOLYSIS
*NAPHTHALENE-- RADIOLYSIS
400600* --Chemistry--Radiation Chemistry
CATIONS
DECAY
ELECTRON BEAMS
GAMMA RADIATION
INFRARED SPECTRA
LOW TEMPERATURE
N40300* --Chemistry--Radiation Chemistry
ORGANIC BROMINE COMPOUNDS
SCAVENGING
SOLUTIONS
TRANSIENTS