Pulsed Hollow Cathode Lamp Research Articles

Atomic Absorption Measurements in a Q-Switched Laser Plume Using Pulsed Hollow Cathode Lamps

Quantitative atomic absorption measurements on transient plasmas induced by a Q-switched laser beam were made using pulsed hollow cathode lamps. Calibration curves were obtained for 0.002 to 0.15% Cu in an aluminum alloy and 0.013 to 0.124% Mn in graphite pellets. The dependence of the atomic absorption characteristics upon changes in laser energy and upon atmospheric gas and pressure is discussed.

The Improvement of Signal to Noise Ratio Using a Pulsed Hollow Cathode Lamp and Gated Detector for Atomic Fluorescence Measurements

Abstract An expression for the maximum increase in signal to noise ratio obtainable with a pulsed hollow cathode lamp as primary source for atomic fluorescence measurements is derived under certain assumptions. Experience with copper and calcium hollow cathode lamps showed that by using these lamps in the pulsed mode in conjunction with a gated detector, the increase in signal to noise ratios obtained are less than a factor of 5, due to self-absorption broadening of the primary source emission lines.

The Use of Pulsed Hollow Cathode Lamps in Atomic Fluorescence Flame Spectrometry

Abstract An initial investigation of a pulsed hollow cathode lamp has been made to determine its advantage in decreasing the limit of detection in atomic fluorescence flame spectrometry. From the results obtained with the pulsed system utilizing a boxcar integrator readout, it can be concluded that pulsed hollow cathode lamps provide a greatly improved signal-to-noise ratio as compared with the conventional hollow cathode system.

Pulsed hollow cathode light sources

Spectroscopic measurements of the light emitted by pulsed hollow cathode lamps have been made as a function of cathode material and geometry, buffer gas and buffer gas pressure, and the size and shape of the exciting current pulse. From these observations the following generalizations can be made. The source exhibits the same general properties with any metal cathode material and with any geometry. Excitation increases with increasing peak current between 30 and 1500 A and is essentially independent of the shape of the current pulse as long as the pulse is not oscillatory. It increases with increasing buffer gas pressure over the range of stable operation of the source between 5 and 50 torr. Buffer gases with high ionization potentials increase ionization while molecular gases depress it. Time-resolved measurements show that the excitation temperature in the afterglow decreases almost linearly with time. Electron density is independent of pressure but increases linearly with increasing peak current. Electron density also decreases linearly with time in the afterglow. Finally, lines from higher ionization stages appear earliest in the light source output. The dependence of excitation and ionization on pressure, buffer gas, peak current and time can be used to roughly sort lines by their upper energy level in the analysis of complex atomic spectra.