Ck. Pan et Fl. King, ATOMIC-EMISSION SPECTROMETRY EMPLOYING A PULSED RADIO-FREQUENCY-POWERED GLOW-DISCHARGE, Applied spectroscopy, 47(12), 1993, pp. 2096-2101
A radio-frequency (rf)-powered glow discharge pulsed at 50 Hz with a 2
5% duty cycle is used as an atomization/excitation source for analytic
al atomic emission spectrometry. Compromise working conditions are est
ablished at 0.8 Torr argon pressure and 80 to 90 W peak applied power.
Analyte emission intensities are found to increase with increases in
discharge pressure and peak applied rf power to an upper limit corresp
onding with the onset of discharge instability. The observed emission
signal intensity is influenced strongly by changes in the cathode-to-a
node separation distance. Long-term analytical signal stability is exh
ibited by this source at rf powers up to 90 W in the absence of extern
al cooling because of operation in the pulsed mode. The maximum attain
able stable emission signal with pulsed operation is approximately fou
r times greater than that attainable with steady-state operation. The
analytical utility of this source is demonstrated through determinatio
ns of trace elements in coal fly ash and graphite samples with limits
of detection in the tens of parts-per-million range.