We demonstrate rotational excitation spectroscopy with the scanning tunneling microscope for physisorbed hydrogen and its isotopes hydrogen-deuterid and deuterium. The observed excitation energies are very close to the gas phase values and show the expected scaling with moment of inertia. Since these energies are characteristic for the molecular nuclear spin states we are able to identify the para and ortho species of hydrogen and deuterium, respectively. We thereby demonstrate nuclear spin sensitivity with unprecedented spatial resolution.
@article{arxiv.1307.7046,
title = {Distinction of Nuclear Spin States with the Scanning Tunneling Microscope},
author = {Fabian Donat Natterer and François Patthey and Harald Brune},
journal= {arXiv preprint arXiv:1307.7046},
year = {2013}
}