Field - and Photoassisted Field Emission Studies of Calcium Fluoride Coated Silicon Tips V.N. Konopsky, V.V. Zhirnov, N.S. Sokolov, J.C. Alvarez, E.I. Givargizov, L.V. Bormatova, V.S. Letokhov and S.K. Sekatskii J. Phys. IV France, 06 C5 (1996) C5-129-C5-134 DOI: 10.1051/jp4:1996521