Crossover between the Adiabatic and Nonadiabatic Limits of Thermal Electron Transfer: Verifying the Landau-Zener Formula

The semiclassical models of nonadiabatic transition were proposed first by Landau and Zener in 1932, which has been widely used in study of electron transfer (ET); however, experimental substantiation of the Landau-Zener formula remains challenging. Herein, employing the Marcus-Hush theory, thermal ET in mixed-valence complexes { [Mo2]-(ph)n-[Mo2] }+ (n = 1-3) is investigated and the Landau-Zener analysis performed in the adiabatic and nonadiabatic limits. Evidently, the Landau-Zener formula is valid in the adiabatic regime in a broader range of conditions than the theoretical limitation known as the narrow avoided-crossing. The intermediate system is identified with an overall transition probability (𝛋el) of ~ 0.5, which is resolved by the contributions from the single and the first multiple passage. The results unify the contemporary ET theories under the semiclassical framework. The obtained insights help to understand and control the ET processes in biological and chemical systems.

Effect of Vibrational Transitions on the Nonthermal Charge Transfer Probability

In the framework of the stochastic approach, the effect of transitions between the vibrational sublevels of products on the ultrafast dynamics of “hot” (non-thermal) electron transfer in donor — acceptor complexes dissolved in a polar medium has been investigated. An analytical expression has been obtained for the probability of electron transfer, which takes into account the transition between the vibrational states of products and the mutual influence of sinks. Quantitative estimates of the scale of the mutual influence of sinks on the probability of electron transfer are made.

Перенос электрона между разнородными лантаноидами в кристаллах BaF-=SUB=-2-=/SUB=- --- II механизмы переноса

The processes of electron transfer from a divalent lanthanide acceptor (Eu, Sm, Yb) to a trivalent lanthanide donor (Nd, Sm, Dy, Tm, Yb) and reverse thermal transfer are studied in barium fluoride crystals. Electron phototransfer at room temperatures is accompanied by a counter-movement of the charge-compensating interstitial fluorine. In the process of photobleaching at low temperatures, the divalent lanthanide donor turns out to be near the interstitial fluorine, which causes its 4f-5d absorption bands to shift to the red. The magnitude of the shift increases with decreasing size of the lanthanide in the series (Nd, Sm, Dy, Tm, Yb). Detailed mechanisms of photo and thermal electron transfer between heterogeneous lanthanides in BaF2 crystals are analyzed.

Photocatalytic fluoroalkylation reactions of organic compounds

Photocatalytic methods for fluoroalkyl-radical generation provide more convenient alternatives to the classical perfluoroalkyl-radical (Rf) production through chemical initiators, such as azo or peroxide compounds or the employment of transition metals through a thermal electron transfer (ET) initiation process.