Surface electronic structure of the (3 × 2) reconstruction induced by Yb on a Si(1 1 1) surface

We have investigated the electronic structure of the Yb/Si(1 1 1)-(3 × 2) surface using angle-resolved photoelectron spectroscopy. Five surface states have been identified in the gap of the bulk band projection. Among these five surface state, the dispersions of three of them agree well with those of the surface states of monovalent atom adsorbed Si(1 1 1)-(3 × 1) surfaces. The dispersions of the two other surface states agree well with those observed on the Ca/Si(1 1 1)-(3 × 2) surface, whose basic structure is the same as that of monovalent atom adsorbed Si(1 1 1)-(3 × 1) surfaces. Taking these results into account, we conclude that the five surface states observed in the band gap originate from the orbitals of Si atoms that form a honeycomb-chain-channel structure.     

Anomalous nuclear spin-lattice relaxation in copper small particles

Anomalously long nuclear spin-lattice relaxation time is expected in small metallic particles when the life time width of the conduction electron energy levels is smaller than their mean spacing. A new method for setting nuclear magnetization to zero is developed in order to measure the relaxation time in Cu small particles. The anomaly is observed in the relaxation of⁶³Cu in the particles with the diameters smaller than 100 A at temperatures below 0.5 K.     

Diversified synthetic approaches to the carbapenem antibiotics based on symmetrization-asymmetrization concept

cis-Fused bicyclic β-lactam compound 9, a key intermediate to cis-substituted carbapenem antibiotics, has been synthesized in optically pure form based on symmetrization-asymmetrization concept.