Defect pairs ofFcenters and substitutionalH−ions (Ucenters) in alkali halides. Reso

Abstract

Defect pairs of F and U centers ["FH(H } centers"] were observed for the first time, created by laserlight induced aggregation of F centers in NaC1, Kcl, and RbC1 crystals doped with high concentrations of substitutional H defects {U centers). The formation of these pairs was indentified by the appearance of three sharp H local-mode lines in the Raman spectrum of F centers (due to the replacement of one of the 12 Cl neighbors by a small-mass H ion). Raman studies of these local mode lines observed in diA'erent scattering geometries (A, g Eg T2g) and in first and second order, reveal their symmetry and identify them as the three orthogonal linear vibrations of the H defect in a (110)pair configuration with the F center.A simple mode1, based on the Van der %'aal interaction between the vibrating 0 dipole and the induced electronic dipole at the F center, explains well the observed local-model shifts, A speculative discussion is given on the absorption, emission, and photochemical properties of this pair formed from the two simplest prototypes of an electronic and local-model defect

Dynamics of nuclear wave packets at theFcenter in alkali halides

“…Modulation spectroscopy with external perturbations such as stress [14][15][16][17][18][19][20], electric [21][22][23][24][25][26] and magnetic fields [27][28][29][30][31][32] has shown relative strengths of the electron-phonon couplings and electronic structures influenced by the pseudo-Jahn-Teller effect. Raman scattering spectroscopy has directly elucidated the strengths of the electron-phonon couplings [33][34][35][36][37][38][39][40][41][42][43][44]. These measurements have revealed adiabatic potential energy surfaces (APESs) of the (meta-)stable states, i.e.…”

Dynamics of nuclear wave packet in the excited state of KCl F centers

“…This result suggests that the LO mode couples strongly to the electron which has a spatially spread wave function [15,16]. In the present experiment, we observe the NWP oscillation around the RES, which corresponds to the equilibrium position of the lattice in the excited state.…”

Observation of nuclear wave packets in the excited state of the F-center in alkali halides

“…In the Raman spectra [6], the enhancement of the LO modes around 6.0 THz is observed under excitation resonant with the higher excited states (3p, 4p,y) rather than the first excited state (2p state). This result suggests that the LO mode at 6.0 THz couples strongly to the electron with a spatially spread wave function [18,19]. The electron-nuclear double-resonance (ENDOR) measurement [20] reveals that in the RES the probability amplitude of the radial electron wave function approaches the maximum at 3d (d is the nearest cation-anion distance, i.e., d ¼ a/2) and decreases very gradually; the amplitude has one-tenth of the maximum value at 6.6d.…”