The self-trapping by the nondiagonal particle-phonon interaction between two quasi-degenerate energy levels of exitonic subsystem, is studied. We propose this is realized in charge transfer exciton, where the directions of the poralization give the quasi-degeneracy, as in quasi-one-dimensional compound A-PMDA. We present a quantitative theory for the optical properties (light absorption and time-resolved luminescence) of the resonating states, which gives a consistent resolution for the long-standing puzzles in A-PMDA.
AbstractQuasi-one dimensional (1D) conductors of the TTF-TCNQ family of charge transfer salts exhibit a Peierls transition which stabilizes a periodic lattice distortion (PLD), accompanied by a charge density wave (CDW) modulation, with an incommensurate 2
Mixed-stack charge-transfer (CT) complexes undergoing the neutral-ionic (N-I) phase transition are molecular
materials formed of stacks where electron donor (D) and acceptor (A) molecules regularly alternate. In the N phase, the CT is
low and molecules are situated on inversion centers, while in the I phase, the increase of CT is accompanied by a lattice
distortion (dimerization process and symmetry breaking). The one-dimensional (1D) architecture triggers the chain
multistability by stabilizing lattice-relaxed (LR)-CT excitations ...D° A° D° A° $(D^+A^-)(D^+A^-)(D^+A^-)$ Do A"
D° A° D°... These
1D nano-scale objects are at the heart of the equilibrium N-I phase transition and govern the fascinating physical properties
such as giant dielectric response or photo-induced phase transformations. In this contribution, the 1D character of these critical
excitations will be demonstrated by direct observation using high resolution X-Ray diffraction.
Twisted One-Dimensional Charge Transfer and Related Y-Shaped Chromophores with a 4H-Pyranylidene Donor: Synthesis and Optical Properties