TY - JOUR

T1 - Relation between CIDNP formed upon geminate and bulk recombination of radical pairs

AU - Sosnovsky, Denis V.

AU - Morozova, Olga B.

AU - Yurkovskaya, Alexandra V.

AU - Ivanov, Konstantin L.

N1 - Publisher Copyright: © 2017 Author(s).

PY - 2017/7/14

Y1 - 2017/7/14

N2 - A theoretical approach to time-resolved Chemically Induced Dynamic Nuclear Polarization (CIDNP) is proposed, which allows one to obtain the general relation between polarization formed upon recombination of geminate spin-correlated radical pairs, the so-called G-pairs, and upon recombination of radical pairs formed by encounters of free radicals in solution, the so-called F-pairs. This relation is described by a universal parameter denoted as γ. In this work, the γ value is computed for the arbitrary spin multiplicity, singlet or triplet, of the precursor of the G-pairs as well as for arbitrary recombination rate constants of radical pairs in singlet and triplet states, kS and kT, respectively. Furthermore, the treatment is extended to the situation where radicals undergo transformation resulting in different reactivity or magnetic parameters for F-pairs and G-pairs. The proposed theory enables modeling of time-resolved CIDNP data in cases where (i) both recombination channels are active and (ii) fast protonation/deprotonation of radicals changes the effective γ value.

AB - A theoretical approach to time-resolved Chemically Induced Dynamic Nuclear Polarization (CIDNP) is proposed, which allows one to obtain the general relation between polarization formed upon recombination of geminate spin-correlated radical pairs, the so-called G-pairs, and upon recombination of radical pairs formed by encounters of free radicals in solution, the so-called F-pairs. This relation is described by a universal parameter denoted as γ. In this work, the γ value is computed for the arbitrary spin multiplicity, singlet or triplet, of the precursor of the G-pairs as well as for arbitrary recombination rate constants of radical pairs in singlet and triplet states, kS and kT, respectively. Furthermore, the treatment is extended to the situation where radicals undergo transformation resulting in different reactivity or magnetic parameters for F-pairs and G-pairs. The proposed theory enables modeling of time-resolved CIDNP data in cases where (i) both recombination channels are active and (ii) fast protonation/deprotonation of radicals changes the effective γ value.

KW - DYNAMIC NUCLEAR-POLARIZATION

KW - INTEGRAL ENCOUNTER THEORY

KW - LASER FLASH-PHOTOLYSIS

KW - TIME-RESOLVED CIDNP

KW - DISSOCIATION REACTION STAGES

KW - AQUEOUS-SOLUTION

KW - MULTISTAGE REACTIONS

KW - ELECTRON-TRANSFER

KW - FT EPR

KW - KINETIC-EQUATIONS

UR - http://www.scopus.com/inward/record.url?scp=85024107783&partnerID=8YFLogxK

U2 - 10.1063/1.4986243

DO - 10.1063/1.4986243

M3 - Article

C2 - 28711061

AN - SCOPUS:85024107783

VL - 147

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 2

M1 - 024303

ER -