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

The relations between the vaporized amounts, vaporization behavior and spectral line intensity of europium 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, 216 ppm of europium as europium oxide and various concentration of sodium fluoride as a spectrographic buffer substance. The element was excited by d. c. arc discharge, and the concentration of europium remaining in graphite powder after the discharge was measured by the neutron activation analysis. It was revealed that the vaporized amounts were increased and the temperature of anode was raised with an increase of the arc current. The spectral line intensity of Eu 2813.9Ådepended on the vaporized amounts in the argon atmosphere. Under the conditions involving arc current 4.95.0A, electrode gap 3 mm, discharge time 60 sec., and NaF concentration 1.02.0%, the vaporized amounts were 7.78×10-8g/mg sample at the anode crater in the air and 3.89×10-8g/mg sample in argon atmosphere. Under the same anode temperature, the vaporized amounts behavior of europium showed little difference in the air and in argon atmosphere, but the line intensity of Eu 2813.9Å was higher in the latter. In spite of the difference in boiling point of europium and sodium, the vaporization behaviors of the two elements in a spectrographic buffer of sodium fluoride were closely related. The vaporized amounts of europium in the sample without NaF did not depend on the discharge time, both in the air and in argon atmosphere.