Electrical resistance of a monatomic step on a crystal surface

We have succeeded in measuring the resistance across a single atomic step through a monatomic-layer metal on a crystal surface, Si(111)(sqrt[3]xsqrt[3])-Ag, using three independent methods, which yielded consistent values of the resistance. Two of the methods were direct measurements with monolithic microscopic four-point probes and four-tip scanning tunneling microscope probes. The third method was the analysis of electron standing waves near step edges, combined with the Landauer formula for 2D conductors. The conductivity across a monatomic step was determined to be about 5 x 10(3) Omega(-1) m(-1). Electron transport across an atomic step is modeled as a tunneling process through an energy-barrier height approximately equal to the work function.     

A novel method for the direct derivatization of straight-chain aliphatic carboxylates after trapping on anion-exchange resin

A novel procedure for the characterization of traces of lipophilic straight-chain aliphatic carboxylate ions in aqueous samples is described. The carboxylates are adsorbed on an Amberlyst A26 [Cl^-] resin column. The resin is then dried and suspended in methyl iodide at room temperature. A gas Chromatographic analysis of the methyl iodide solution allows the determination of the carboxylates as their methyl esters. Full characterization of each carboxylate with an overall recovery over 84% from 1 ppm aqueous sample solutions is attained.     

The photochemical reactions of 5H-benzo[a]phenoxazin-5-one with alkylthiols and thiophenol

6-Alkylthio- and 6-phenylthio-5H-benzo[a]phenoxazin-5-ones have been synthesized by the photochemical reaction of 5H-benzo[a]phenoxazin-5-one with alkylthiols and thiophenol.     

Interfacial instability of a condensing vapor bubble in a subcooled liquid

The European Physical Journal Special Topics - A special attention is paid to the condensing and collapsing processes of vapor bubble injected into a subcooled pool. We try to extract the...     

Creation of superior carboxyfluorescein dyes by blocking donor-excited photoinduced electron transfer

[Structure: see text] Carboxyfluoresceins are widely utilized as fluorescence labeling reagents, but we recently found that their emission intensity is markedly decreased after esterification. On the basis of our hypothesis that the fluorescence decrease is due to a donor-excited photoinduced electron transfer (d-PeT) process, we have developed novel carboxyfluorescein derivatives in which the d-PeT process is hampered, and the emission intensity is not decreased upon esterification. These novel dye derivatives display high quantum yields and are expected to be useful as labeling agents.     

Chiral bisphosphazides as dual basic enantioselective catalysts

Chiral bisphosphazides complexed with lithium salts efficiently catalyze the direct enantioselective 1,4-addition of dialkyl malonates to acyclic enones. Spectroscopic studies on the stoichiometry of the bisphosphazide and lithium salt have indicated the formation of a 1:1 species as the active enantioselective catalyst. It is suggested that the catalyst generates a complex of the protonated phosphazide and the chiral nucleophile as the key intermediate. The phosphazide moiety appears to be a promising dual basic functionality for stereo- and chemoselective catalytic transformations.     

Nuclear moments of neutron-rich aluminum isotopes

Ground-state magnetic-dipole moments (μ) of ^30-32Al and electric quadrupole moments (Q) of ^31,32Al have been measured with the β-NMR method using spin-polarized radioactive-isotope beams produced in projectile-fragmentation reactions. Beams of ^30-32Al were obtained by using RIKEN projectile-fragment separator RIPS after the fragmentation of ⁴⁰Ar projectiles at an energy of E = 95A MeV on a ⁹³Nb target. The obtained μ_exp[^30-32Al] and values agree well with shell-model calculations within the sd shell using the USD interaction. Also, Q_exp[³¹Al] was found to be small. Thus, we can conclude that these aluminum isotopes are located outside the island of inversion.