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Laser-excited photoelectron emission from a variety of materials can provide modulated electron beams of high-current density and brightness. In applications such as lithography and in electronbeam devices where current density is important, the incident laser intensity at the emitter surface will be high, and the photocathode materials properties should be different from those needed, for example, in optical detectors. For process applications it is important that the electron source be unaffected by exposure to air. Thin films of organic materials on metallic substrates are attractive because they exhibit higher quantum yields than most metals, resist oxidation, and have intermediate electronic states which enhance two-photon photoelectric generation. Two-photon emission is interesting because chemically inert surfaces tend to have photoelectric threshold wavelengths below 300 nm, where simple continuous or highrepetition-rate lasers are not yet available. At the high-current (and power) densities required in several applications, use of a nonlinear emission mechanism may not pose additional problems, yet it permits use of more convenient laser wavelengths. The excited singlet or lowest triplet states of dye molecules can serve as the resonant intermediate level in such a process. Our calculations show that for a reasonable choice of parameters it should be possible to generate current densities in the 1-100-A/cm 2 range by this method.We measured the electron emissions of a variety of materials using ArF, nitrogen, and neodymium lasers at wavelengths from 193 to 355 nm (Nd third harmonic). Single-photon and two-photon responses were separated by noting the dependence of the photoelectron flux on the laser beam spot size. The organic coatings were produced by deposition from solvents, by spinning using photoresist technology, and by direct evaporation in high vacuum. Photoelectrons are created only within the outer 10 nm of the film, and reduced emission due to surface charging occurs for layers thicker than ~100 nm. Our best results to date have been obtained with vacuum evaporated films on copper substrates.Irradiation at 193 and 266 nm produced singlephoton electron emission. Technologically useful quantum yields (10 -4 -3 X 10~4) have been measured for phthalocyanine, chlorophyll, crystal violet, and rhodamine 6G coatings. At high intensities with 355-or 337-nm illumination, intense nonlinear emission is also obtained. Yields above 10~5 electron/incident photon can be reached near 1 MW/cm 2 with coumarin 480 and POPOP, for example.Single-nanosecond pulse excitation cannot exploit the triplet manifold because singlet-triplet crossing rates are 10 7 -10 8 /s. Experiments with long-pulse and continuous lasers to demonstrate triplet photoemission are beginning.(Poster paper)THK18 .pdf