Advantage of Argon-helium Mixed Gas Plasmas for Carbon Determination in Glow Discharge Optical Emission Spectrometry.

For the sensitive determination of carbon in steel samples, an argon–helium mixture plasma gas was employed in glow discharge optical emission spectrometry. The emission lines of carbon have relatively high excitation energies, which implies that the excitations by helium whose ions and metastable atoms have larger internal energies could produce the excited states of carbon more readily. Comparison in the calibration curves yields the detection sensitivity obtained with the argon–helium mixture was enhanced than with the argon gas alone by a factor of 3.