Intrinsic Enhancement Factors of the Spin−Orbit Coupling Mechanism Polarization in the Duroquinone−N,N-Dimethylaniline Derivative Systems

Abstract

Dynamics of the electron spin polarization of the quinone anion radical generated from the photoinduced electron transfer between duroquinone (DQ) and N,N-dimethylaniline (DMA) as well as its p-halogen substituents (4XDMA) has been investigated by using transient absorption and FTEPR spectroscopies. The radical yield decreased with increasing atomic number of the halogen in the donor. The intrinsic enhancement factors of net absorptive polarization due to the spin−orbit coupling mechanism (SOCM) of V SOCM = 2, 17, and 25 were determined in the unit of thermal equilibrium polarization at room temperature for the DQ-4ClDMA, DQ-4BrDMA, and DQ-4IDMA systems, respectively. The net absorptive spin polarization observed has been discussed in terms of SOC interaction of the triplet contact radical ion pair (CRIP) state with the ground state, which is coupled with the singlet CRIP states in the solvent coordinate.

Spin dynamics and zero-field splitting constants of the triplet exciplex generated by photoinduced electron transfer reaction between erythrosin B and duroquinone

“…The rate constants of the exciplex formation and ET in the exciplexes were determined from the buildup and decay rates of the bands. We have found that the chemically induced dynamic electron polarization (CIDEP) technique is also a powerful tool to study triplet exciplexes [5,6,[17][18][19][20][21]. Net-emissive (E) and unusual net-absorptive (A) CIDEP spectra have been observed in several photoinduced ET reaction systems containing heavy atoms.…”

“…Net-emissive (E) and unusual net-absorptive (A) CIDEP spectra have been observed in several photoinduced ET reaction systems containing heavy atoms. These CIDEP 3 July 2002 Chemical Physics Letters 360 (2002) [13][14][15][16][17][18][19][20][21] www.elsevier.com/locate/cplett effects were interpreted in terms of the sublevel selective population type triplet mechanism (p-TM) or normal TM of the precursor triplet state and the sublevel selective depopulation type triplet mechanism (d-TM) of the triplet exciplex, respectively. The unusual net-A polarization is attributable to sublevel selective intersystem crossing (ISC) from the triplet exciplex or contact radical pair to the singlet ground state.…”

Magnetic field dependence of the deactivation rates of triplet azocumene in solution

“…especially a T 1> S 0 ISC with rates above 10 9 s ¡1 , are ful®lled only in rare cases. Thus, up to now, CIDEP from a d-type triplet mechanism has been observed experimentally only for a few radicals formed from exciplexes of some excited dye molecules with heavy atom substituted electron donors [7]. The existence of a fast state selective T 1> S 0 ISC in these exciplexes had been postulated before by Steiner et al [8,9] to explain an observed pronounced magnetic ®eld dependence of the radical yield in those systems.…”

Solvent effects on the intrinsic enhancement factors of the triplet exciplex generated by photoinduced electron transfer reaction between eosin Y and duroquinone

“…However, there have been few studies of the intrinsic enhancement factors in triplet exciplex formation systems. For the duroquinone (DQ) plus 4-halogen-N; N-dimethylaniline derivative systems we have determined the intrinsic enhancement factor of the electron spin polarization [16]. Signi®cant solvent e ects on the electron spin polarization and magnetic ®eld e ects on the radical yield were obtained [16,17].…”

“…For the duroquinone (DQ) plus 4-halogen-N; N-dimethylaniline derivative systems we have determined the intrinsic enhancement factor of the electron spin polarization [16]. Signi®cant solvent e ects on the electron spin polarization and magnetic ®eld e ects on the radical yield were obtained [16,17]. In methanol, the S±T 0 mixing due to the normal RPM was observed clearly, suggesting the formation of solvent separated radical ion pairs.…”