Spectra and emission lifetimes of H2CS(Ã 1A2)

Fluorescence spectra and lifetimes of single vibronic levels of the first excited singlet state of H₂CS have been measured under effusive flow conditions. Fluorescence lifetimes of the single vibronic levels decrease from 140±3 μs (0°) to 68 μs(3¹4¹5¹) with increasing excitation energies. The promoting vibrational modes for the non-radiative transition are considered to be the out-of-plane bending (ν₄) and the asymmetric rocking (ν₆) modes rather than the asymmetric stretching mode (ν₅).     

Bio-sensing on a chip with compact discs and nanofibers

This paper describes a novel, sensitive detection system for biomolecules (DNA and proteins etc.) that is integrated in a lab-on-a-chip utilizing optical compact discs (CDs) and bio-nanofibers. The new method comprises a microchannel containing CD grating that confines fragments of unique bacterial cellulose fibrils (BC), which have nanometre scale fibers and holes. A maximum of six times higher sensitivity to detect DNA was obtained with this CD and BC system compared to a conventional method. We also demonstrate an effective light-confining effect for biological application with the new method.     

Optical probing of spin polarization of electrons in quantum dot edge channels

We propose an optical method for the investigation of the quantum dot edge channels by utilizing circularly polarized photoluminescence in the integer-quantum-Hall-effect regime. One of the advantages of our method is that the degree of the spin-polarization of the electrons in the inner- and outer-compressible liquids can be probed separately. The observed polarized photoluminescence spectra can be explained by the calculated electron spin-dependent optical transition probabilities based on the local-spin density approximation.     

STM-based molecular detection of "catch-and-release" of protons for bipyridine bound to phenylene-ethynylene thiol

The protonation/deprotonation response of a novel bipyridine containing (phenylene-ethynylene) thiol adsorbed to a Au surface was investigated with scanning tunneling microscopy (STM), showing reversible changes in the average heights (approximately 50 spots) and the height distribution arising from protonation/deprotonation.     

Lateral displacement by transient mobility in chemisorption of CO on Pt(997)

We investigated adsorbed states of CO on Pt(997) at 11 K using infrared reflection absorption spectroscopy. At 11 K, thermal migration is suppressed and thus the initial chemisorption at terrace sites and step sites is controlled by the transient mobility of the adsorbing molecule. The initial occupation ratio between atop CO on the terrace and atop CO at the step is directly determined to be 3.6:1. With a simple isotropic migration model, we estimated the mean lateral displacement from the first impact point to the initial chemisorption site to be 6.8 A. We also discuss the origin of transient mobility of CO on metal surfaces.     

First-Known High-Nuclearity Copper–Nickel Carbonyl Cluster: [CuxNi35−x(CO)40]5− (with x=3 or 5) Containing an Unprecedented 35-Atom Three-Layer hcp Triangular Stacking Metal-Core Geometry

Reactions of [Ni₆(CO)₁₂]^2- (1) with CuBr₂ have given rise in small yields (10%) to the first example of a close-packed copper-nickel carbonyl cluster; its formulation as [Cu_xNi_35-x(CO)₄₀]^5- (with x=3 or 5) is based upon a low-temperature CCD X-ray crystallographic determination coupled with an elemental analysis and X-ray fluorescence measurements. This air-unstable black pentaanion (2) together with one co-crystallized bromide anion, six [NMe₄]⁺ counterions, and one solvated acetone molecule comprise the crystallographic independent part in a monoclinic unit cell of P2₁/n symmetry (with Z=4). The geometrically unprecedented 35-atom hcp M(A)₂M(B)₃Ni₃₀ polyhedron of pseudo-D_3h symmetry consists of a central 15-atom equilateral ₄M(B)₃Ni₁₂ triangle that is capped on both sides by two symmetry-related 10-atom equilateral ₃M(A)Ni₉ triangles. The 35-atom M(A)₂M(B)₃Ni₃₀ core is encapsulated by 40 COs, whose connectivities, due to an extra CO ligand on one of the three triangular sides, reduce the pseudo D_3h symmetry of the metal core to C_s. An elemental analysis via AA and X-ray fluorescence measurements resulted in Cu/Ni ratios of 3.2/31.8 and 3.7/31.3, respectively, that are consistent with the metal core being either Cu₅Ni₃₀ (i.e., M(A)=M(B)=Cu) or Cu₃Ni₃₂ (i.e., M(A)=Ni; M(B)=Cu). Several attempts to determine the actual stoichiometry of the metal core by use of electrospray FT/MS/ICR measurements were unsuccessful. The maximum metal-core diameter of 2 is ca. 0.41 nm parallel and 0.85 nm perpendicular to the principal 3-fold axis.