Large magnetic field effect on the decay rates of triplet hydrocarbon diradicals

Journal Article · Thu Jun 15 04:00:00 EDT 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100349a019· OSTI ID:6752268

Wang, J; Doubleday, C Jr; Turro, N J ^[1]

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1. Columbia Univ., New York, NY (USA)

Intersystem crossing rate constants, k{sub ISC}, of triplet 1,n-diphenyl 1,n-diyl diradicals (n = number of carbons in diradical chain) generated by type I photolyses of {alpha},{alpha}{prime}-diphenylcycloalkanones were measured in an external magnetic field H variable up to 2 kG. No magnetic field effect was observed for n = 4 and 5, but for n = 9, 11, and 14, k{sub ISC} first increased then decreased as H was increased. For n = 11 and 14, the value of k{sub ISC} decreased to an apparent asymptotic value at high field equal to 0.17 and 0.07, respectively, of the value of k{sub ISC} at H = O. For diradicals with n {ge} 9, it is proposed that, at H = O, electron-nuclear hyperfine coupling is the only important ISC mechanism, that at H = 2 kG electronic spin-lattice relaxation is the major ISC mechanism, that the three triplet magnetic sublevels do not equilibrate during the diradical lifetime, and that one of the outer two triplet magnetic sublevels is preferentially populated initially.

• OSTI ID: 6752268
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:12; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CHEMICAL PROPERTIES
DATA
DATA ANALYSIS
DECAY
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
KINETICS
MAGNETIC FIELD CONFIGURATIONS
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
RADICALS
REACTION KINETICS