title: Distinction of nuclear spin states with the scanning tunneling microscope.
abstract: We demonstrate rotational excitation spectroscopy with the scanning tunneling microscope for physisorbed H(2) and its isotopes HD and D(2). The observed excitation energies are very close to the gas phase values and show the expected scaling with the 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.
authors.affiliation: Institute of Condensed Matter Physics (ICMP), Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: Fabian Donat
authors.initials: FD
authors.lastname: Natterer
authors.forename: François
authors.initials: F
authors.lastname: Patthey
authors.forename: Harald
authors.initials: H
authors.lastname: Brune