Poole-Frenkel ionization of excitons in solid Kr J. Kraft, A. Schrimpf, B. Schweitzer, K. Ibbeken and H.-J. Stöckmann Europhys. Lett., 39 4 (1997) 459-464 Published online: 01 September 2002 DOI: 10.1209/epl/i1997-00377-0