The Fundamental Vibration of Molecular Hydrogen

TL;DR

This study precisely measures the fundamental vibrational frequency of molecular hydrogen isotopologues using Doppler-free laser spectroscopy, providing a critical test of quantum electrodynamics in molecules.

Contribution

It offers highly accurate experimental data for molecular hydrogen vibrations, validating ab initio quantum electrodynamics calculations.

Findings

Measured vibrational frequencies with 2 x 10^-4 cm^-1 accuracy.

Experimental results agree within 1σ with theoretical calculations.

Provides a stringent test of quantum electrodynamics in molecules.

Abstract

The fundamental ground tone vibration of H2, HD, and D2 is determined to an accuracy of 2 x 10^-4 cm^-1 from Doppler-free laser spectroscopy in the collisionless environment of a molecular beam. This rotationless vibrational splitting is derived from the combination difference between electronic excitation from the X^1Sg+, v=0 and v=1 levels to a common EF^1g+, v=0 level. Agreement within $1\sigma$ between the experimental result and a full ab initio calculation provides a stringent test of quantum electrodynamics in a chemically-bound system.