Phonon-assisted anti-Stokes excitation of the fluorescence of Mn2+ ions inthe CsMnCl3 center dot 2H(2)O crystal

We demonstrate that anti-Stokes excitation of Mn2+ ions in the CsMnCl3. 2H( 2)O crystal can occur through multiphonon addition to the energy of the pho tons of exciting light. The deficit dE between the energy of the Mn2+ T-4(1 ) exciton and the photon energy of the He-Ne laser used as the source of il lumination is compensated by simultaneous annihilation of several thermally activated lattice phonons. The absence of two-photon activation of the flu orescence was verified by measurement of the dependence of the fluorescence intensity on the intensity of the exciting light, which appears linear at a fixed energy mismatch dE. (C) 2000 American Institute of Physics. [S1063- 777X(00)00507-7].