The one of the most common source for atomic absorption measurements is the hollow cathode lamp. Usually these kind of lamps consists of a tungsten anode and a cylindrical cathode sealed in a glass tube filled with neon or argon at the pressure of 1 to 5 torr. The cathode is constructed of the metal whose spectrum is desired or serves to support a layer of that metal .
Ionization occurs when a potential difference on the order of 300V is applied across the electrodes. The efficiency of the hollow cathode lamp depends on its geometry and the operating voltage. High voltages,and thus high currents, leads to greater intensities . READ MORE
This advantage is offset somewhat by an increase in Doppler broadening of the emission lines from the lamp. Hollow-cathode lamps are often used as source in AFS. In this application the lamps are pulsed with a duty cycle of 1% to 10% and peak current of 0.1 to 1 A, which increase their peak radiance by a factor of 10 to 100 relative to the steady state radiance of DC operation . A variety of hollow cathode lamps is available commercially . The cathodes of some consists of a mixture of several metals ;such lamps permit the determination fo more than a single element.see more in wikipedia
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