[Paper Review] Photoionization of temperature-controlled nanoparticles in a beam: Accurate and efficient determination of ionization energies and work functions

Atef A. Sheekhoon, Abdelrahman O. Haridy+2 more|arXiv (Cornell University)|Feb 17, 2026

nanoparticles nucleation surface interactions0 citations

TL;DR

The paper demonstrates a beam-based method to determine ionization energies and work functions of temperature-controlled alkali metal nanoparticles by photoionization and Fowler-function fits, achieving ~0.2% precision.

ABSTRACT

A beam of free alkali metal nanoparticles is produced by a condensation source, passed through a thermalizing tube adjustable over a broad temperature range, and ionized by tunable light. High stability of the particle flux and an automated data acquisition routine allow efficient collection of photoionization yield curves. A careful fit of the data to the universal Fowler function makes it possible to obtain nanoparticle ionization energies, and from those, the metal work functions, with $\sim$0.2% precision. The experimental arrangement, nanoparticle thermalization rates, and ionization threshold analysis are described in detail. The use of ultrapure and temperature-controlled gas-phase nanoparticles facilitates the analysis of electronic properties, such as work functions, and of their interplay with thermal lattice dynamics.

Motivation & Objective

• Motivate precise electronic-property characterization of gas-phase nanoparticles in a beam.
• Develop an experimental setup with a condensation source and adjustable thermalization to produce temperature-controlled nanoparticles.
• Enable automated, high-stability acquisition of photoionization yield curves.
• Extract ionization energies and work functions from yields using a Fowler-function fit with high accuracy.

Proposed method

• Produce free alkali metal nanoparticles with a condensation source.
• Thermally tune nanoparticles using a thermalizing tube adjustable over a broad temperature range.
• Ionize nanoparticles with tunable light to obtain photoionization yield curves.
• Apply automated data acquisition for efficient data collection.
• Fit the yields to the universal Fowler function to determine ionization energies and work functions.

Experimental results

Research questions

• RQ1 Can temperature-controlled, gas-phase nanoparticles in a beam yield precise ionization energies and work functions from photoionization data?
• RQ2 How accurately can Fowler-function fits extract electronic properties from measured photoionization yields?
• RQ3 What are the roles of nanoparticle thermalization and flux stability on the precision of extracted energies?

Key findings

• Ionization energies and work functions can be determined with ~0.2% precision from photoionization yields.
• A high-stability nanoparticle flux and automated data acquisition enable efficient collection of yield curves.
• The Fowler-function fit provides a robust method to analyze photoionization thresholds for nanoparticles in a beam.