title: Higher triplet excited states of benzophenones and bimolecular triplet energy transfer measured by using nanosecond-picosecond two-color/two-laser flash photolysis.
abstract: The lifetimes of benzophenone in the higher triplet excited state (BP(T(n))) and several BP derivatives in the T(n) states were measured directly to be tau(T(n))=37+/-7 ps and 20-33 ps, respectively, by using the nanosecond-picosecond (ns-ps) two-color/two-laser flash photolysis method. Based on the direct measurements of tau(T(n)) of BP(T(n)), the triplet energy transfer (TET) from BP(T(n)) to quenchers (Q), such as carbon tetrachloride (CCl4), benzene (Bz), and p-dichlorbenzene (DCB), was investigated. The fast TET from BP(T(n)) to Q can be attributed to the lifetime-dependent quenching process, according to the Ware theoretical model of the bimolecular energy transfer reaction. The contribution of the lifetime-dependent term on k(TET) was 27, 60, and 86% for CCl4, Bz, and DCB as the Q of BP(T(n)), respectively, indicating that the TET from BP(T(n)) to Q is influenced not only by tau(T(n)), but also by the size of Q.
authors.affiliation: Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Xichen
authors.initials: X
authors.lastname: Cai
authors.forename: Masanori
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Mamoru
authors.initials: M
authors.lastname: Fujitsuka
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Majima
mesh_terms: D000042:Absorption; D001554:Benzene / Q000737:chemistry; D001577:Benzophenones / Q000737:chemistry*; D002251:Carbon Tetrachloride / Q000737:chemistry; D002722:Chlorobenzenes / Q000737:chemistry; D004735:Energy Transfer; D007700:Kinetics; D007834:Lasers; D010782:Photolysis; D011789:Quantum Theory; D013997:Time Factors
chemical_list: D001577:Benzophenones; D002722:Chlorobenzenes; D002251:Carbon Tetrachloride; C018511:4-dichlorobenzene; D001554:Benzene