Metal Halide Arc Lamp for Spectroscopic Measurement

An arc discharge in metal halide vapor was investigated to use as an ultraviolet lamp for spectroscopic measurement. The arc tube of the lamp contains mercury, mercury iodide, tantalum, and xenon. The absolute spectral radiance of the new lamp was measured. The strong continuum emission was observed in the wavelength region between 220 and 450 nm. Several lines in this region are also strong as well as the continuum. Short term fluctuations were 0.2% when measured with a measurement system of 0.4-sec response time. The long term decay of the radiance was less than 52% in 2000-hr operation.These characteristics of the new lamp indicate that the lamp is applicable to the light source for spectroscopic measurement, especially for the fluorescent type detector of the liquid chromatography apparatus.