Direct and precise mapping of intramolecular H-atom motion in H2 by an electron-atom Compton scattering experiment

We report an electron-atom Compton scattering experiment on the ${\mathrm{H}}_{2}$ molecule. The momentum distribution of the H atom due to intramolecular motion was obtained by using a protocol developed for the data analysis. Furthermore, it is shown that the experimental result agrees well with associated calculations based on quantum chemistry theory. This indicates not only the validity of the protocol but also the feasibility of use of the experiment as an unconventional molecular spectroscopy, opening the door to direct and precise mapping of intramolecular motion of each atom with different masses.