Using scanning tunneling microscopy, we have studied local surface modifications induced by point contact of a tunnel tip with metallic surfaces. Two distinct types topographical modification are found which correlate directly the chemical condition as determined spectroscopy. Observation dynamics transition from regime to permits an evaluation gap distance prior contact. At spacings s\ensuremath{\lesssim}3 A\r{} significant decrease in apparent barrier height is observed just before...

In scanning thermal microscopy, but also in tunneling the contact between tip and sample plays an important role. The heat transfer across vacuum gap two parallel metallic surfaces, if width is decreased below several microns, has been investigated. At these distances propagating electromagnetic modes die out simultaneously a of nonpropagating surface becomes more probable. conductance should become distance dependent larger than that given by Stefan–Boltzmann law; however, experimental...

${\mathrm{N}}_{2}^{2+}$ ions, produced by electron impact of ${\mathrm{N}}_{2}$, are observed to predissociate into ${\mathrm{N}}^{+}$+${\mathrm{N}}^{+}$ when irradiated a dye laser at photon energies between 14900 and 19500 ${\mathrm{cm}}^{\ensuremath{-}1}$. Five structured bands in the spectrum associated with absorptions from $X^{1}\ensuremath{\Sigma}_{g}^{+}$ ($v=0,1,2$) three predissociated levels $1^{1}\ensuremath{\Pi}_{u}$ state. The two highest believed dissociate tunneling through...

A detailed analysis of contact electrification between metals reveals a mechanism leading to unexpectedly high voltages.

A scanning force microscope operated in the dynamic mode has been used to analyze arrangement of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) molecules on a KBr(001) surface. The do not form close-packed layer but crystallites with shape truncated pyramids. Even after depositing only 0.3 molecular layers PTCDA, these have height 20--30 layers. We able resolve individual top and some facets. results agree known ``herringbone'' structure bulk. comparison experimentally observed...

Simple modification of the electronics a STM allows operation in various tracking modes. Profiles steepest inclination, equal height, equipotential, electrical field lines, etc., can be traced out. The tunnel tip also locked to surface extremity for indefinite time. Some these possibilities were tested experimentally.

GXSM is a full featured and modern scanning probe microscopy (SPM) software. It can be used for powerful multidimensional image/data processing, analysis, visualization. Connected to an instrument, it operating many different flavors of SPM, e.g., tunneling atomic force or, in general, two-dimensional multichannel data acquisition instruments. The core handle types, integer floating point numbers. An easily extendable plug-in architecture provides image analysis manipulation functions. A...

If a current of electrons flows through normal conductor (in contrast to superconductor), it is impeded by local scattering at defects as well phonon scattering. Both effects contribute the voltage drop observed for macroscopic complex system described Ohm's law. Although this concept established, has not yet been measured around individual on atomic scale. We have monatomic step in real space restricting surface layer. For Si(111)-( [see text]3 x text]3)-Ag monotonous transition with width...

Laser-induced emission of the Sr2 molecule consisting discrete molecular fluorescence series, regularly modulated continuous and an unstructured continuum was observed in gas phase at excitation wavelengths between 600 450 nm. The analysis line spectra provides Dunham coefficients RKR potentials for X 1Σ+g ground state excited A 1Σ+u state. main spectroscopic constants are ωe=40.32 cm−1, Re=4.45 Å De=1060 cm−1 ωe=85.07 Re=3.95 De=5400 which is due to bound-continuum transitions from a...

Scanning tunneling potentiometry (STP) is a powerful tool to analyze the conductance through thin conducting layers with lateral resolution in nanometer range. In this work, we show how commercial ultrahigh vacuum multiprobe system, equipped four independent tips, can be used perform STP experiments. Two tips are gently pushed into surface applying current layer of interest. Simultaneously, topography and potential distribution across metal film measured third tip. The signal-to-noise ratio...

The influence of surface plasmons excited in a polycrystalline silver film on the tunneling current scanning microscope (STM) has been analyzed. cause an additional flow electrons from tungsten tip to order up 50 pA. This process is independent polarity applied bias voltage, thereby excluding effects thermal expansion. different nature ordinary and plasmon induced clearly revealed by their dependence gap distance. local distribution intensity signal reveals structures nanometer scale. Some...

The initial growth of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) was analysed. Ultrathin films with coverages up to two layers were prepared on a (111) orientated copper single crystal by means vapour deposition in an ultrahigh-vacuum chamber. characterized situ scanning tunnelling microscopy (STM). Within the first layer, different structures found. Both exhibit herringbone-like arrangement molecules, which is also found (102) plane α and β bulk phases. two-dimensional unit cell...

We report on a lightwave-driven scanning tunneling microscope based home-built and compact, commercial, cost-effective terahertz-generation unit with repetition rate of 100 MHz. The measurements are performed in an ultrahigh vacuum at temperatures between 8.5 300 K. cross-correlation the pump probe pulses indicates temporal resolution order picosecond. In terms spatial resolution, CO molecules, step edges, atomically resolved terraces readily observed terahertz images, sometimes better...

We analyzed the transport of ballistic electrons through organic molecules on uniformly flat surfaces bismuth grown silicon. For fullerene C 60 and for a planar molecule (3,4,9,10-perylene-tetracarboxylic acid dianhydride), signals revealed characteristic submolecular patterns that indicated where was enhanced or attenuated. The associated to specific electronic molecular states. At electron energies few volts, this “scanning near-field transmission microscopy” method could be applied...

The noise in the tunneling current of a scanning microscope (STM) has been investigated. At gap voltages above few mV shows 1/f spectral distribution over range 1 Hz to 100 kHz. However, at zero bias white scaling like thermal for equivalent resistance is found. Due its exponential distance dependence, this can be used adjust tip-to-sample with an accuracy similar conventional STM method. performance based on principle demonstrated.

If copper phthalocyanine (CuPc) molecules are deposited on a Au(111) surface covered with monolayer of ${\mathrm{C}}_{60}$, the found to adsorb individually onto close-packed layer ${\mathrm{C}}_{60}$. As adsorption site CuPc is not symmetric respect underlying ${\mathrm{C}}_{60}$ layer, molecule has six equivalent orientations according hexagonal packing Scanning tunneling microscopy (STM) measurements reveal that at room temperature, may hop between these sites due thermal activation and...