Nonradiative DKR processes: revisiting the theory. III. Multimode approaches

TL;DR

This paper revisits the theory of nonradiative DKR processes, proposing a multimode approach to model relaxation in NaI F centers, and assesses the efficiency of nonradiative deexcitation mechanisms.

Contribution

It introduces a method using a single effective frequency for multimode relaxation and discusses 2s-2p mixing via a T_{1u} vibrational mode, providing new insights into nonradiative rates.

Findings

Nonradiative deexcitation rates are lower than intervibrational relaxations.

The effective frequency approach simplifies multimode relaxation modeling.

Nonradiative processes are inefficient due to phonon exchange complexity.

Abstract

We outline a method for dealing with the relaxation of optically excited NaI F centers in terms of a single effective frequency along a multimode coordinate. The 2s-2p mixing through coupling to a T_{1u} vibrational mode is also discussed with optimistic conclusions. Equilibrium nonradiative deexcitation rates are estimated and compared with intervibrational relaxations so as to assess the efficiency of the nonequilibrium DKR deexcitation. They show the former not to be competitive, due to the large number of phonons exchanged.