Effect of target surface on the elastic properties of fast fullerenes

Abstract

C + 60 fullerenes with keV energies are scattered at grazing angles of incidence from atomically clean and flat LiF(001), KCl(001), Al(001), Be(0001), Ni(110) surfaces as well as p(2×1) and p(3×1) oxygen superstructures on Ni(110). The elastic properties of C60 are derived from a comparison of experimental data with 3D molecular dynamics simulations for different interaction potentials. In terms of a simple model for the hybridization of C60 with the surface, we find evidence for a close relation between electronic structure of the surface and elasticity of C60.PACS numbers: 79.20. Rf, 34.35.+a, 79.60.Bm, 78.30.Na, 61.85.+p The elastic properties of carbon nanostructures play an important role for applications in composite materials, nanomechanical devices, or molecular electronics [1][2][3][4][5][6][7]. In such configurations, carbon nanostructures will be embedded, supported, or in contact with a matrix of material, that will affect the properties of the carbon nanostructure. Prominent examples are strong covalent interactions of fullerenes with surfaces such as Si(100), Ni(110), or Pt(111) resulting in dissociation of fullerenes in thermal desorption spectroscopy (TDS) experiments or charge transfer processes inducing semiconductorconductor phase transitions [8][9][10]. By an appropriate choice of the surrounding material, these interactions might be exploited for an optimized performance of the building blocks of future carbon nanostructure devices or materials.From a fundamental point of view, it is important to provide experimental data on the properties of single carbon nanostructures in different environments. Here, we focus on the elastic properties of the prototype of a carbon nanostructure, C 60 [11], in front of single crystal surfaces for deformation energies up to some 10 eV. As the ultimate experimental tool, a single molecule vise with two opposing non-deformable surfaces, cannot be realized, we performed scattering experiments in the surface channeling regime, i.e. under grazing incidence, where the deformation of the surface is negligible due to the small energy transfer to the surface in small-angle scattering events [12,13]. The velocity of the molecules is still sufficiently slow in order to guarantee an adiabatic regime for the interaction with the surface [14]. Via the incident energy and the angle of incidence, the molecule can be exposed to well-defined deformation energies. The elastic properties of the molecules are studied by means of the kinetic energy of outgoing fullerenes. In the case of a stiff/soft molecule, a small/large amount of the energy is transferred to internal degrees of freedom and the outgoing kinetic energy is large/small. During the last two decades, a fair number of studies have been devoted to elastic properties, stability, fragmentation, and charge transfer during scattering of hyperthermal fullerenes from surfaces [15][16][17][18][19][20][21][22]. However, for angles of incidence Φ in ≥ 10• with respect to the surface, the deformation of the surface was consi...