We have analyzed the effect of the tip atomic species on the tip–sample separation and the bias-voltage dependence of apparent barrier height (ABH) on an Al(1
0
0) surface using the boundary-matching ...scattering-state density functional method, which can be used to calculate electron states under applied bias voltages self-consistently within the density functional theory. We found that, from the dependence of the tip–sample separation, the difference between measurements with the two tip atomic species is larger in the ABH than in the maximum barrier height evaluated from the calculated potential profile. Furthermore, we found that the bias-polarity dependence of the ABH measured with the Na tip shows behavior opposite to that shown by the ABH measured with the Al tip. These results can be understood from the difference in the degree of lateral confinement of tunneling electrons in the tunneling barrier region between the two atomic species.
Furfural is an important intermediate compound of the Maillard reaction of pentose or ascorbic acid. We examined the browning of furfural and lysine by heating and found a yellow compound, called ...furpipate, (E)-3(2-furylmethylidene)-3H, 4H, 5H, 6H-pyridine-2-carboxylic acid. Furpipate is a novel pipecolic acid derivative and shows absorption maxima at 375 nm and 310 nm under acidic and alkaline conditions, respectively. This compound was the major colored compound of the heated solution containing lysine and furfural.
The total syntheses of the marine bisindole alkaloids, hamacanthins were achieved by a novel transamidation–cyclization of
N-(2-aminoethyl)-2-oxoethanamides to 3,5- and 3,6-disubstituted ...piperazinones.
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The effect of interface modification by insertion of Se layer on the formation of InAs dots on GaAs(001) is investigated by means of reflection high energy electron diffraction (RHEED) and atomic ...force microscope. The incorporation of a Se single layer into the interface is found to give rise to an extended critical thickness, presumably due to reduction of interface energy by the formation of Se–Ga/Se–In bonds. The reorganization of InAs supercritical 2D layers to form InAs dots on Se-treated GaAs(001) surface is reviewed by AFM images.
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