Angular Distributions and Total Yields of Bi Sputtered by 20 keV He$^{+}$, Ne$^{+}$ and Ar$^{+}$

The angular distributions of neutral atoms sputtered from the surface of solid Bi by normally incident 20 keV He$^{+}$, Ne$^{+}$ and Ar$^{+}$ ions have been measured. The sputtered atoms were collected on pure aluminum foils under ultrahigh vacuum conditions, and the collector foils were subsequently analyzed using heavy ion Rutherford backscattering spectroscopy. The angular distributions obtained were integrated to determine the total sputtering yields of Bi for the different incident ions. Details of the measurements and data analysis are presented.