Holographic scattering in centrosymmetric Na-2[Fe(CN)(5)NO]center dot 2H(2)O

Holographic light scattering is discovered in single crystals of sodiumnitr oprusside, Na-2[Fe(CN)(5)NO] . 2H(2)O, although light amplification on the basis of wave mixing is in centrosymmetric crystals forbidden. By excitatio n of long-living metastable states at temperatures below T = 100 K a radial ly symmetric intensity distribution appears round the directly transmitted pump beam, which results from diffraction of the incoming light at written parasitic holographic phase gratings. Tilting the crystal the corona turns into two cones of diffracted light as a result of the Bragg conditions. [S0 031-9007(99)08849-3].