Measurement ofUIandUIIrelative oscillator strengths

Abstract

Relative $\mathrm{gf}$ values for 49 prominent ${\mathrm{U}}_{\mathrm{II}}$ lines and 21 of the strongest ${\mathrm{U}}_{\mathrm{I}}$ lines have been measured. The ${\mathrm{U}}_{\mathrm{II}}$ measurements were made using a wall-stabilized arc into which the uranium was introduced in the form of U${\mathrm{F}}_6$. The ${\mathrm{U}}_{\mathrm{I}}$ values were measured with a flow-stabilized arc which is essentially a free-burning arc stabilized by streaming argon around one of the electrodes which is formed from a molten ball of uranium held in a tungsten cup. Temperatures in the wall-stabilized and flow-stabilized arc were 10 500 K and 5500 K, respectively. The ${\mathrm{U}}_{\mathrm{I}}$ relative $\mathrm{gf}$ values were placed on an absolute scale employing a recent lifetime determination for the 27 887-${\mathrm{cm}}^{-1\mathrm{}}$ level of ${\mathrm{U}}_{\mathrm{I}}$. This absolute scale was extended to the ${\mathrm{U}}_{\mathrm{II}}$ values by measuring the relative intensity of a ${\mathrm{U}}_{\mathrm{I}}$ and a ${\mathrm{U}}_{\mathrm{II}}$ line in the wall-stabilized arc.