Hydrogen Atomic Motions in Different Intramolecular Environments: H₂O, H₂S, and Formaldehyde (H₂CO)

Atoms within complex environments are always moving, but this motion is only investigated through spectroscopic techniques that look at the collective motion of the rotations or normal vibrational modes. Atomic momentum spectroscopy, where a high energy electron back-scatters from an atom within a molecule, has the potential to investigate the motion of specific atoms which can vary based on their chemical environment. To test and demonstrate the sensitivity of this technique, we have performed experiments on the H atomic motion within water (H₂O), hydrogen sulfide (H₂S), and formaldehyde (H₂CO) systems. Through these experiments, we benchmark and test the theoretical description of the hydrogen atom's motion within these different chemical systems. The good agreement we observe between the experimental and theoretical data and variation in behavior across the chemical series illustrate the potential of AMS as a sensitive probe of the internal atomic motions within different chemical environments.