Composition analysis of single semiconductor nanowires using pulsed-laser atom probe tomography

We report the composition analysis of single InAs and Si semiconductor nanowires using pulsed-laser atom probe tomography. The experimental conditions and sample geometries needed to realize 3-D composition mapping are described in detail. InAs mass spectra obtained using voltage pulses and laser pulses are compared, and are found to be superior for pulsed-laser evaporation. The ability to analyze intrinsic Si nanowires using pulsed laser evaporation is demonstrated. No peaks associated with the gold catalyst used were found in the InAs or the Si nanowire mass spectra. PACS 68.70.+w; 61.82.Fk; 61.72.Ss     

The initiation and characterization of single bimolecular reactions with a scanning tunneling microscope

A scanning tunneling microscope (STM) operating at 9 K in ultrahigh vacuum was used to initiate a bimolecular reaction between isolated hydrogen sulfide and dicarbon molecules on the Cu(001) surface. The reaction products ethynyl (CCH) and sulfhydryl (SH) were identified by inelastic electron tunneling spectroscopy (STM-IETS) and by sequentially removing hydrogen atoms from an H2S molecule using energetic tunneling electrons. For comparison, the thermal diffusion and reaction of H2S and CC at 45 K and H2O and CC at 9 K were also observed.     

On some nonself mappings

Let X be a Banach space, let K be a non–empty closed subset of X and let T : K → X be a non–self mapping. The main result of this paper is that if T satisfies the contractive–type condition (1.1) below and maps ?K (?K the boundary of K) into K then T has a unique fixed point in K.