Isotope and temperature effects on the work function of lithium and its nanoparticles

The work function (WF) of a solid surface or the ionization energy (IE) of a nanoparticle is the minimum energy required to remove an electron and is a key material property. Despite its significance, the temperature dependence of WF and IE has received relatively little attention due to the small magnitude of the effect; however, it provides valuable insights into the interplay between a material’s electronic properties and its structural dynamics. We conducted a high-precision photoionization measurement on isolated Li-6 and Li-7 nanoparticles in a beam, focusing on the temperature dependence of the photoemission threshold. We were able to resolve an isotope-dependent variation in this dependence, reflecting the differences in isotope lattice dynamics. These results highlight the role of isotope effects in the thermodynamic properties of materials and their potential influence on electronic and electrochemical behavior.