Improvement of the Detection Limits in Radio-frequency-powered Glow Discharge Optical Emission Spectrometry Associated with Bias-current Conduction Method

Abstract

A d.c. bias current driven by the self-bias voltage which is conducted through the r.f.-powered glow discharge plasma varies the emission characteristics drastically, leading to improvement of the detection power in the optical emission spectrometry. By conducting the bias currents of 20-30 mA, the emission intensities of the atomic resonance lines were 10-20 times larger than those obtained with conventional r.f.-powered plasmas. The detection limits for determination of alloyed elements in the Fe-based binary alloy samples were estimated to be 1.6×10^-3% Cr for Crl 425.43 nm, 7×10^-4% Mn for Mnl 403.10nm, 1.9×10^-3% Cu for Cu l 327.40 nm, 1.1x 10^-3% Al for All 396.16 nm, and 6.6×10^-3% Ni for Ni I 352.45 nm.