Photodetachment Spectroscopy of As$^{\_}$

Tunable infrared laser photodetachment spectroscopy has been performed on As$^{\_ }$ using a crossed laser-ion beam apparatus. The relative photodetachment cross section for neutral production was measured, revealing a threshold near 804.8 meV, interpreted as the opening of the As$^{\_}$ (4$p^{4} \quad ^{3}P_{2})$ to As (4$p^{3} \quad ^{4}S_{3/2})$ ground state to ground state transition. The $\Delta $E ($^{3}$P$_{1}$ -- $^{3}$P$_{2})$ fine structure splitting is also measured. The values of the present work are consistent with, and reduce the uncertainty of, previous measurements [1,2]. [1] Lippa, T. P., \textit{et al}, Journal of Chemical Physics \textbf{109}, 10727 (1998). [2] Haeffler, G., \textit{et. al}. Zeitshrift f\"{u}r Physik D \textbf{42}, 263 (1997).