Abstract
Precision spectroscopy of molecular hydrogen can be used to test the quantum electrodynamics theory and determine the proton-to-electron mass ratio in a four-body system. Cavity-enhanced double-resonance spectroscopy is proposed to determine highly-excited rotation-vibration energies of HD with high precision. As a demonstration, the V-type comb-locked cavity-assisted double resonance (COCA-DR) spectroscopy of HD is measured by pumping the P(1) (2-0) line and probing the R(1) line in the same overtone band. The sum value of the two transition frequencies is determined to be 426 889 423 917 (26) kHz, representing a new test of theoretical calculations.
GRAPHICAL ABSTRACT
![](/cms/asset/2de878d9-5bdf-4d00-85e5-ba36f6dbd305/tmph_a_2127382_uf0001_oc.jpg)
Acknowledgments
The authors acknowledge Prof. K. K. Lehmann for discussion of the density matrix calculations.
Disclosure statement
No potential conflict of interest was reported by the author(s).