Where gaseous samples are encountered (semiconductor end-point determination of CVD chamber cleaning) the process becomes more like atomic absorption spectroscopy (AAS). The McPherson Model 629 windowless discharge lamp operated with Helium as a carrier gas offers a low clean background. The relative intensity of emission indicates concentration of an element within the sample. They emit radiation at characteristic ‘fingerprint’ wavelengths of the elements involved. Molecules of sample media are broken into charged ions after colliding with the electrons and charged ions in the lamps plasma. This windowless hollow cathode UV lamp is versatile it can simultaneously introduce and ionize samples. Since there is no limiting window, this UV source works in the more energetic range of wavelengths from double ionized Helium at 30 nanometers up to the Visible light range (2 to 40 eV). Mirrors can reflect the light to an analytical optical system, a spectrometer or spectrophotometer. It is similar to inductively coupled plasma (ICP) atomic emission spectroscopy systems. These emit electromagnetic radiation at wavelengths characteristic of the gas flowing through the system. The Model 629 hollow cathode UV lamp produces excited atoms and ions. Computer controlled gas flow and constant current power supply improve stability for better spectroscopy. This broad-spectrum source emits ionized gas emission lines with little or no absorption by neutral gas. > VUV Sample Chambers New improved stability windowless hollow cathode UV lampĬhelmsford, MA, Aug– McPherson is pleased to announce new and improved stability with flow controlled McPherson windowless, hollow cathode UV lamp Model 629.
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