title: Ultrafast Photochemistry of Copper(II) Monochlorocomplexes in Methanol and Acetonitrile by Broadband Deep-UV-to-Near-IR Femtosecond Transient Absorption Spectroscopy.
abstract: Photochemistry of copper(II) monochlorocomplexes in methanol and acetonitrile solutions is studied by UV-pump/broadband deep-UV-to-near-IR probe femtosecond transient absorption spectroscopy. Upon 255 and 266 nm excitation, the complexes in acetonitrile and methanol, respectively, are promoted to the excited ligand-to-metal charge transfer (LMCT) state, which has a short (sub-250 fs) lifetime. From the LMCT state, the complexes decay via internal conversion to lower-lying ligand field (LF) d-d excited states or the vibrationally hot ground electronic state. A minor fraction of the excited complexes relaxes to the LF electronic excited states, which are relatively long-lived with lifetimes >1 ns. Also, in methanol solutions, about 3% of the LMCT-excited copper(II) monochlorocomplexes dissociate forming copper(I) solvatocomplexes and chlorine atoms, which then further react forming long-lived photoproducts. In acetonitrile, about 50% of the LMCT-excited copper(II) monochlorocomplexes dissociate forming radical and ionic products in a ratio of 3:2. Another minor process observed following excitation only in methanol solutions is the re-equilibration between several forms of the copper(II) ground-state complexes present in solutions. This re-equilibration occurs on a time scale from sub-nanoseconds to nanoseconds.
authors.affiliation: Saint-Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg, 199034 Russia.
authors.forename: Andrey S
authors.initials: AS
authors.lastname: Mereshchenko
authors.affiliation: Saint-Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg, 199034 Russia.
authors.forename: Pavel K
authors.initials: PK
authors.lastname: Olshin
authors.affiliation: Saint-Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg, 199034 Russia.
authors.forename: Olesya S
authors.initials: OS
authors.lastname: Myasnikova
authors.affiliation: Saint-Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg, 199034 Russia.
authors.forename: Maxim S
authors.initials: MS
authors.lastname: Panov
authors.affiliation: Saint-Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg, 199034 Russia.
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Kochemirovsky
authors.affiliation: Saint-Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg, 199034 Russia.
authors.forename: Mikhail Yu
authors.initials: MY
authors.lastname: Skripkin
authors.forename: Pavel N
authors.initials: PN
authors.lastname: Moroz
authors.forename: Mikhail
authors.initials: M
authors.lastname: Zamkov
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Tarnovsky