We investigated the photoyield from CsI, p and n doped and undoped amorphous silicon and some organometallic (decamethyl-ferrocene,1,1',dimethylferrocene and ruthenocene) reflective photocathodes, in the spectral range 140-220 nm. The measurements were made in a current collection mode, in vacuum and in methane. Powder and crystal forms of CsI were used for evaporation of bulk and porous photocathodes. The radiation resistance of CsI was measured at doses reaching 4500 Gy. The effect on the quantum efficiency of various n and p doping levels of amorphous silicon was measured.