Competition between energy and phase relaxation in electronic curve crossing processes

Abstract

We present results from simulations of vibrational energy and phase relaxation and electronic curve crossing using a multilevel formulation of Redfield theory, which demonstrate the shortcomings of the optical Bloch approximation and the importance of coherence transfer processes in the relaxation dynamics of multilevel systems. Specifically, we show that for a harmonic well, energy relaxation can occur with retention of vibrational phase, and that for sufficiently strong electronic coupling, the product of an electronic curve crossing process can be formed vibrationally coherent even when no coherence is present in the initially excited state.

Real-time observation of vibrational coherence persisting after internal conversion and vibrational relaxation in cyanine dye molecules

“…It is difficult to believe that the phase of wavepacket motion gets little distortion with passing through several internal conversion processes and losing large energy of 1.55 eV. However, recently there are some papers which support such phenomenon theoretically [26].…”

Spectral exhibition of electron-vibrational relaxation in P* state of Rhodobacter sphaeroides reaction centers

“…Surprisingly, this lifetime is much greater than the 100-200 fs time constant for energy transfer from B* or H* to P (van Brederode and van Grondelle 1999). The long-lived coherence was theoretically predicted by Jean and Fleming (1995) using the multilevel Redfield theory. It was shown that, for a harmonic well, the vibrational phase can be retained during energy relaxation.…”

“…Density-matrix formalism permits us to take into account the finite time of vibrational relaxations and dephasing (Redfield 1965). On the basis of the Redfield theory, a theoretical study of coherent electron transfer was performed by the approach of a single nuclear mode coupled to two electronic states (Jean and Fleming 1995;Jean et al 1992;Jean 1994). The oscillatory dynamics in the P*-stimulated emission band were theoretically studied by an approach of one electronic transition coupled to one or two vibrational modes Leegwater 1995;Lin et al 1995).…”

Vibrational Relaxation and Intersystem Crossing of Binuclear Metal Complexes in Solution

“…The harmonicity guarantees frequency matching between the vibronic levels, resulting in very efficient coherence transfer between vibronic levels. 26 The cage-like structure of the molecule protects the oscillator from the stochastically fluctuating solvent, also reducing pure dephasing. This behavior shows close resemblance to the vibrational relaxation of dihalogens in rare gas matrices.…”