Vacuum Ultraviolet Light-Source, 30nm+

The McPherson, Inc. Model 629 is a windowless, hollow cathode source in which the negative discharge glow is viewed directly. Ionized gas emission lines are produced and can be conveniently viewed with little or no absorption by neutral gas. The sources water-cooled anode and cathode are electrically isolated. A differential pumping stage is available as accessory to allow direct connection to experiment systems operating at lower vacuum pressures.

The McPherson Model 629 may be operated with a variety of inert gases. Helium (He) is among the most popular. Operating pressures ~3*10-1 torr and discharge current ~500mA are optimum for emission of He II ion lines around 30.4nm. With unchanged discharge current, higher pressure (~1 torr) provides optimum output at He I, 58.4nm. Argon and Neon are other popular gases. This source may be used directly for ultraviolet spectroscopy experiments where unfiltered multi-line excitation is acceptable. Combine the Model 629 source with a high throughput vacuum monochromator like the 200mm focal length McPherson Model 234/302 to benefit applications requiring greater specificity. This McPherson monochromator provides sub nanometer wavelength resolution – easily discriminating between multiple emission lines - and rejecting out of band energy. Line of sight optical path is optionally available for the Model 629 light source simplifying alignment with optical or sampling systems. The Model 629 windowless, hollow cathode source is useful for wavelength calibration and as general emission source for wavelengths 30nm and longer.