We have studied the desorption of positive ions from a LiF(110) crystal surface using positron and electron irradiation at 500 eV to examine the interaction between positrons and ionic crystals. Only monatomic ions, such as ${\mathrm{H}}^{+}$, ${\mathrm{Li}}^{+}$, and ${\mathrm{F}}^{+}$, are detected under electron irradiation. However, positron irradiation leads to the significant desorption of ionic molecules, specifically, ${\mathrm{FH}}^{+}$ and ${\mathrm{F}}_2^{+}$. Molecular ion yields are more sensitive to temperature than atomic ion yields. Based on the findings, we propose a desorption model in which positronic compounds are initially produced at the surface and subsequently desorbed as molecular ions via Auger decay following positron annihilation.

• Received 26 May 2023
• Revised 2 September 2023
• Accepted 11 September 2023

DOI:https://doi.org/10.1103/PhysRevLett.131.143201