High Precision Determination of the Planck Constant by Modern Photoemission Spectroscopy

TL;DR

This paper reports a highly precise measurement of the Planck constant using modern photoemission spectroscopy, significantly improving accuracy over previous photoelectric effect methods and demonstrating its potential as a competitive technique in fundamental constant determination.

Contribution

It introduces a novel application of photoemission spectroscopy for measuring the Planck constant with unprecedented precision, surpassing earlier photoelectric effect methods.

Findings

Measured Planck constant with 4-5 orders of magnitude improved accuracy.

Demonstrated photoemission spectroscopy as a highly precise method.

Proposed potential for further precision enhancements.

Abstract

The Planck constant, with its mathematical symbol $h$, is a fundamental constant in quantum mechanics that is associated with the quantization of light and matter. It is also of fundamental importance to metrology, such as the definition of ohm and volt, and the latest definition of kilogram. One of the first measurements to determine the Planck constant is based on the photoelectric effect, however, the values thus obtained so far have exhibited a large uncertainty. The accepted value of the Planck constant, 6.62607015$\times$10$^{-34}$ J$\cdot$s, is obtained from one of the most precise methods, the Kibble balance, which involves quantum Hall effect, Josephson effect and the use of the International Prototype of the Kilogram (IPK) or its copies. Here we present a precise determination of the Planck constant by modern photoemission spectroscopy technique. Through the direct use of the Einstein's photoelectric equation, the Planck constant is determined by measuring accurately the energy position of the gold Fermi level using light sources with various photon wavelengths. The precision of the measured Planck constant, 6.62610(13)$\times$10$^{-34}$ J$\cdot$s, is four to five orders of magnitude improved from the previous photoelectric effect measurements. It has rendered photoemission method to become one of the most accurate methods in determining the Planck constant. We propose that this direct method of photoemission spectroscopy has advantages and a potential to further increase its measurement precision of the Planck constant to be comparable to the most accurate methods that are available at present.