Seeing melting through an electronic measurement
The work function of isolated sodium and potassium nanoparticles changes measurably at the solid–liquid transition.
What the experiment revealed
Temperature-dependent work functions show a gradual decline in the solid phase, followed by a discontinuity and change of slope at melting. The reported transition temperatures are approximately 280 K for sodium and 240 K for potassium nanoparticles, below the corresponding bulk melting points.
For particles approximately 7–9 nm in diameter, the melting-point depression is consistent with finite-size Gibbs–Thomson behavior. The result establishes photoionization threshold measurements as a probe of phase transitions in free nanoparticles.
Publication: A. O. Haridy, A. A. Sheekhoon, and V. V. Kresin, Physical Review B 113, L041404 (2026). Editors’ Suggestion.