Ken Miyajima

Electronic and geometric properties of exohedral sodium- and gold-fullerenes

The electronic and geometric properties of gas-phase exohedral C60NaN−, C70NaN−, and C60AuN− cluster anions are investigated. Time-of-flight mass spectrometry and photoelectron spectroscopy (PES) reveal complex-specific arrangements of the sodium and the gold atoms on the fullerene cage. The electron affinity of C60AuN clearly shows even–odd alternation with the number of Au atoms, which suggests a “dry” structure where Au atoms aggregate as a cluster on the C60. In contrast, C60NaN and C70NaN show a “wet” structure having the Na atoms packed into stable trimers on the surface. For C60NaN (N=0 to 4), PES experiments at a high photodetachment energy (5.81 eV) allow us to deduce the net charge transferred from the sodium atoms to the lowest unoccupied molecular orbital of the fullerene. For larger C60NaN, moreover, a metallic transition is shown to occur at N∼13, and analysis of the adiabatic electron affinity variations allows the identification of the first magic sizes corresponding to electronic shell cl...

Charge distributions in multiple-decker sandwich clusters of lanthanide–cyclooctatetraene: Application of Na-atom doping

Abstract In gas phase, Na-atom adducts were produced for organometallic lanthanide complexes of Ln n (C 8 H 8 ) n +1 [Ln=europium (Eu) and holmium (Ho); C 8 H 8 =1,3,5,7-cyclooctatetraene (COT)] by a combination of two-laser vaporization and a molecular beam method. The number of attached Na atoms can be reasonably explained by charge distributions of the complex, where Eu and Ho atoms exist as Eu 2+ and Ho 3+ , respectively, and C 8 H 8 molecules as COT 2− , accepting two excess electrons. The behavior of the Na adducts chemically demonstrates that the organometallic lanthanide complex is formed through ionic bonding, implying that it is possible to be isolated as its Na salt.

Generation and electronic properties of lanthanide–cyclooctatetraene organometallic clusters in gas phase

Abstract.Organometallic clusters of lanthanide (Ln = Nd, Er, Eu, and Yb) and 1,3,5,7-cyclooctatetraene (C8H8) were produced by a combination of laser vaporization and molecular beam methods. In the mass spectra of [Lnn(C8H8)m], compositions of m=n+1 were magic numbers. From mass spectrometry, photoionization spectroscopy, and photoelectron spectroscopy, we have concluded that these magic-numbered clusters take multiple-decker sandwich structures in which Ln atoms and C8H8 molecules are alternatedly piled up. These sandwich clusters are formed through ionic bonds composed of multiply charged cations [Lnk+xa0(k=2 and 3)] and multiply charged anions [C8H8h-xa0(h=1, 1.5, and 2)].