Carbon superatom thin films

Assembling clusters on surfaces has emerged as a novel way to grow thin films with targeted properties. In particular, it has been proposed from experimental findings that fullerenes deposited on surfaces could give rise to thin films retaining the bonding properties of the incident clusters. However the microscopic structure of such films is still unclear. By performing quantum molecular dynamics simulations, we show that C_28 fullerenes can be deposited on a surface to form a thin film of nearly defect free molecules, which act as carbon superatoms. Our findings help clarify the structure of disordered small fullerene films and also support the recently proposed hyperdiamond model for solid C_28.Comment: 13 pages, RevTeX, 2 figures available as black and white PostScript files; color PostScript and/or gif files available upon reques

THE SPECTRA OF Sm+2Sm^{+2} IN BARIUM, STRONTIUM, AND CALCIUM HALOFLUORIDES

Author Institution: RCA LaboratoriesDivalent samarium in single crystals of the halofluorides of barium, strontium, and calcium has a number of groups of emission lines in the spectral range $5500 {\AA}-8000 {\AA}$. The transitions, which correspond to $f^{6}, ^{5}D_{j}\longrightarrow f^{6}, ^{7}F_{j1+}$ where $J_{\max} = 3$ and $J^{\prime}_{\max} = 4$, are primarily electric dipole ones. Magnetic dipole transitions are observed in many cases where the symmetry selection rules forbid electric dipole ones. A rather complete spectral assignment has been made with the aid of emission, absorption, and Zeeman spectra. Experimental values of the crystal field parameters for $Sm^{+2}$ in a site of symmetry $C_{4v}=4$ mm have been obtained and a comparison of the crystal field matrix elements of the $^{7}F$ and $^{5}D$ states has been made. The fluorescence lifetimes as a function of temperature provide information about relative values of some of the non-radiative processes