title: Ortho and para hydrogen dimers on G/SiC(0001): combined STM and DFT study.
abstract: The hydrogen (H) dimer structures formed upon room-temperature H adsorption on single layer graphene (SLG) grown on SiC(0001) are addressed using a combined theoretical-experimental approach. Our study includes density functional theory (DFT) calculations for the full (6√3 × 6√3)R30° unit cell of the SLG/SiC(0001) substrate and atomically resolved scanning tunneling microscopy images determining simultaneously the graphene lattice and the internal structure of the H adsorbates. We show that H atoms normally group in chemisorbed coupled structures of different sizes and orientations. We make an atomic scale determination of the most stable experimental geometries, the small dimers and ellipsoid-shaped features, and we assign them to hydrogen adsorbed in para dimers and ortho dimers configuration, respectively, through comparison with the theory.
authors.affiliation: Centro de Astrobiología INTA-CSIC, Carretera de Ajalvir, km. 4, ES-28850 Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Merino
authors.forename: M
authors.initials: M
authors.lastname: Švec
authors.forename: J I
authors.initials: JI
authors.lastname: Martínez
authors.forename: P
authors.initials: P
authors.lastname: Mutombo
authors.forename: C
authors.initials: C
authors.lastname: Gonzalez
authors.forename: J A
authors.initials: JA
authors.lastname: Martín-Gago
authors.forename: P L
authors.initials: PL
authors.lastname: de Andres
authors.forename: P
authors.initials: P
authors.lastname: Jelinek
mesh_terms: D019281:Dimerization; D006108:Graphite / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D016252:Microscopy, Scanning Tunneling; D011789:Quantum Theory
chemical_list: D006108:Graphite; D006859:Hydrogen