Dept. of Applied Physics
Oregon Graduate Center
A noble gas ion laser with strong transitions in the 196-225 nm wavelength region has been developed for use as an illuminator in a photoelectron microscope. The laser is pulsed, and it can be operated at repetition rates up to 200 Hz to produce average output powers up to 5.0 mW at 219 nm. This is comparable to the output of the brightest available incoherent source, a Hg-Xe-Cd arc lamp that produces 2.6 mW of usable light in the 221-226 nm range. The laser has the advantage that it can be focused to produce much higher intensities than the arc lamp, and less total power is necessary. But the pulsed laser has a low duty cycle (~ 10[superscript minus 5]), and the corresponding peak powers (~ 300 watts) result in a space-charge-limited resolution of approximately 500 Ã when the laser illuminates a phthalocyanine target. The magnitude of this aberration is proportional to beam current. Consequently, the resolution o can be improved to about 50 Ã by decreasing the input power, or increasing the duty cycle, by a factor of 100-1000. Techniques for achieving such an improvement are suggested.
Plummer, Brian P., "Ultraviolet laser sources for photoelectron microscopy" (1979). Scholar Archive. 63.