Search for Light-Induced Intrinsic Localized Modes: Negative Result

Abstract

We have attempted to induce the theoretically predicted anharmonic lattice modes called intrinsic localized modes in the NaI single crystal lattice by UV excitation of the impurity electronic states of Tl⁺ substitution centers. Comparison of low-temperature phonon density of states measured by inelastic neutron scattering with and without simultaneous UV illumination of the sample did not reveal significant difference. Results are discussed in the context of possible improvements of the proposed experiment.

Keywords:

• Alkali halides
• intrinsic localized modes
• phonon density of states
• inelastic neutron scattering

Acknowledgments

This work was supported by the Czech Science Foundation (Project GACR P204/11/P404). The authors are grateful to Martin Nikl from the Institute of Physics, Academy of Sciences of the Czech Republic, for encouragement and critical reading of the manuscript.