The vaporized amounts, vaporization behavior and spectral line intensity of copper in graphite powder by arc discharge

The relations between vaporized amounts, vaporization behavior and spectral line intensity of copper in graphite powder have been examined with graphite electrodes under varying arc discharge conditions and buffer concentrations. Standard samples were prepared with highly purified graphite powder, 10 ppm of copper as cupric oxide and various amounts of lithium fluoride as a spectrographic buffer substance. The element was excited by the d.c. arc discharge, and the concentration of copper remaining in graphite powder after the discharge was measured by the neutron activation analysis. It was shown that the vaporized amounts were increased and the temperature of anode was raised with an increase of the arc current. Under the conditions involving arc current 8.512.6A, electrode gap 3 mm, discharge time 60 sec., the vaporized amounts were 9×10-9g/mg sample on both anode and cathode craters in the air, and 5×10-9g/mg sample in argon atmosphere. The argon atmosphere gave, under the same vaporized amounts as in the air, a lower line intensity of Cu 3247.5Å. The ratio of Cobs. to Cstand. in the air, characterizing a vaporaization behavior of copper, depended mostly on the arc current and the discharge time. The vaporized amounts on both anode and cathode craters as well as the line intensity of Cu 3247.5Å were increased by an addition of lithium fluoride of a concentration from 0.5 to 2.0% to the sample under arc discharge.