Research output: Contribution to journal › Article › peer-review
Nanoviscosity effect on the spin chemistry of an electron donor/Pt-complex /electron acceptor triad - classical and quantum kinetics interpretation. / Riese, Stefan; Mungenast, Lena; Schmiedel, Alexander et al.
In: Molecular Physics, Vol. 117, No. 19, 02.10.2019, p. 2632-2644.Research output: Contribution to journal › Article › peer-review
}
TY - JOUR
T1 - Nanoviscosity effect on the spin chemistry of an electron donor/Pt-complex /electron acceptor triad - classical and quantum kinetics interpretation
AU - Riese, Stefan
AU - Mungenast, Lena
AU - Schmiedel, Alexander
AU - Holzapfel, Marco
AU - Lukzen, Nikita N.
AU - Steiner, Ulrich E.
AU - Lambert, Christoph
PY - 2019/10/2
Y1 - 2019/10/2
N2 - The magnetic-field dependent charge recombination kinetics upon ns-laser flash photolysis of a novel triarylamine/cyclometalated platinum complex/napthalenediimide triad (DPtA) have been measured in tetrahydrofuran (THF) and polytetrahydrofuran (pTHF) to study the spinchemical effect of a large increase of the macroviscosity of the solvent by a factor of about 1000. The magnetic-field dependence of the decay kinetics of the charge separated state has been accurately reproduced by a classical kinetic model, wherein the rate constants of transitions between spin substates of different Zeeman energy are represented by a single magnetic-field dependent rate constant k±. In THF, the magnetic-field dependence of k± is given by a double Lorentzian function which, in a double log plot, shows two characteristic steps that can be consistently assigned to the magnetic field inhibition of the coherent and incoherent i.e. relaxational spin mixing mechanism. In pTHF, the magnetic field effect on k± is a single step function decreasing to its limiting value at about 5 times lower fields than in THF. As shown by a quantum theoretical simulation, in this solvent coherent and incoherent processes are contributing equally at all fields. The nanoviscosity of pTHF appears to be much smaller than its macroviscosity.
AB - The magnetic-field dependent charge recombination kinetics upon ns-laser flash photolysis of a novel triarylamine/cyclometalated platinum complex/napthalenediimide triad (DPtA) have been measured in tetrahydrofuran (THF) and polytetrahydrofuran (pTHF) to study the spinchemical effect of a large increase of the macroviscosity of the solvent by a factor of about 1000. The magnetic-field dependence of the decay kinetics of the charge separated state has been accurately reproduced by a classical kinetic model, wherein the rate constants of transitions between spin substates of different Zeeman energy are represented by a single magnetic-field dependent rate constant k±. In THF, the magnetic-field dependence of k± is given by a double Lorentzian function which, in a double log plot, shows two characteristic steps that can be consistently assigned to the magnetic field inhibition of the coherent and incoherent i.e. relaxational spin mixing mechanism. In pTHF, the magnetic field effect on k± is a single step function decreasing to its limiting value at about 5 times lower fields than in THF. As shown by a quantum theoretical simulation, in this solvent coherent and incoherent processes are contributing equally at all fields. The nanoviscosity of pTHF appears to be much smaller than its macroviscosity.
KW - donor acceptor systems
KW - Photoinduced electron transfer
KW - polymer nanoviscosity
KW - spin chemistry
KW - GEMINATE RECOMBINATION
KW - MAGNETIC-FIELD DEPENDENCE
KW - COHERENT
KW - PHOTOCHEMISTRY
KW - RELAXATION
KW - CHEMICAL CONTROL
KW - MODEL
KW - RADICAL-PAIR
UR - http://www.scopus.com/inward/record.url?scp=85052946638&partnerID=8YFLogxK
U2 - 10.1080/00268976.2018.1511867
DO - 10.1080/00268976.2018.1511867
M3 - Article
AN - SCOPUS:85052946638
VL - 117
SP - 2632
EP - 2644
JO - Molecular Physics
JF - Molecular Physics
SN - 0026-8976
IS - 19
ER -
ID: 16484156