Light-driven water flips in crystalline solids: science and applications in optical data storage

Program Code: 

Prof Hans Riesen (

Description of Work: 


The project aims to exploit our recent discovery of a thousandfold increase in the efficiency of non-photochemical spectral hole-burning upon partial deuteration of Cr3+ doped NaMgAl(oxalate)3. 9H2O with the effect vanishing on complete deuteration. This observation is a significant discovery in hole-burning spectroscopy of inorganic systems in the solid state. The mechanism is based on photo induced 180o flips of the partially deuterated water molecules of crystallization. Importantly, the nonphotochemical holes are stable up to 120 K and hence suitable for applications at liquid nitrogen temperatures.

Description of Work:

  • Water flips induced by d-d and f-f transitions of one or more of the transition metal and lanthanide ions in inorganic hydrates will be explored by holeburning spectroscopy. Because of their low electron-phonon coupling, f-f transitions are prime candidates for higher temperature hole-burning materials.
  • The dependence of spectral hole-burning properties, such as quantum efficiency and spontaneous hole-filling on: structural details, the temperature, the potential barrier height, rotational tunnelling splittings, external electric and magnetic fields and the degree of deuteration, will be investigated in a range of selected compounds.
  • The potential of the selected materials as the active media in portable frequency standards, in laser stabilization schemes and in optical data storage and signal processing devices will be explored.