The importance of a solvent in regulating the adhesion forces between surfaces is studied quantitatively with scanning force microscopy. Both samples and tips are coated alkyl thiolate monolayers type HS(CH2)10Y measurements conducted as function terminal group Y (Y = CH2CH3, CH2OCH3, CO2CH3, CO(NH2), CO2H, CH2OH) (water, ethanol, n-hexadecane). Adhesive water span greatest range (0.30−12.5 nN), hydrophobic adhering most strongly hydrophilic weakly. In ethanol adhesive substantially smaller...

A new technique, combining a pulsed supersonic molecular-beam source and time-resolved surface infrared spectroscopy, has been devised to measure the microscopic diffusion of molecules at surfaces. Following rapid dose periodically stepped Pt(111) crystal face low total coverage CO (\ensuremath{\sim}0.006 monolayer), time evolution migrating from terrace step sites was monitored with temporal resolution as fast 5 msec. When compared simple kinetic model, data reveal statistical hopping rates...

The microscopic diffusion of CO on stepped Pt(111) crystal surfaces has been investigated with pulsed molecular beam–time-resolved surface infrared methods. Following a rapid exposure to CO, we record the time evolution vibrational spectra as diffuse from initial random distribution thermodynamically favored step sites. data are simulated model that describes kinetics across terraces, well filling We critically evaluate this and general experimental approach by extending our previous...

Growth of an ultrathin lead oxide layer causes massive changes in the shape crystallites. The dynamics this process was investigated with time-lapsed scanning tunneling microscopy. Pure crystallites proved extremely resistant to oxidation. Once nucleated by surface impurities, monolayer films grew readily on (111) microfacets autocatalytic process. anisotropic growth orthorhombic (massicot structure) most rapid along direction weakest lead-oxygen bonding, which suggests that edge...

The oxygen-induced breakup of vicinal Ag(110) surfaces into (110) facets and step bunches is measured with scanning tunneling microscopy. Faceting transitions are recorded in real time at room temperature for two surface orientations. A misoriented by 2\ifmmode^\circ\else\textdegree\fi{} towards [001] via the growth isolated nuclei. Step-position fluctuations increasing magnitude observed prior to faceting, revealing a critical terrace width \ensuremath{\sim}100 \AA{}. In contrast, oxygen...

A non-local Hall bar geometry is used to detect neutral-current effects in graphene on silicon dioxide. Disorder tuned by the addition of Au or Ir adatoms ultra-high vacuum. reproducible effect found both as-fabricated and adatom-decorated graphene. The angle exhibits a complex but dependence gate voltage disorder, notably breaks electron-hole symmetry. An exponential length between inverse-Hall probes indicates neutral current relaxation approximately 300 nm. short lack precession parallel...

The recently discovered large nonsaturating magnetoresistance in semimetal $\mathrm{WT}{\mathrm{e}}_{2}$ may result from near-perfect electron-hole compensation, however recent reports question whether the compensation is adequate to explain observations. Experiments on significantly uncompensated are needed. We measure ${\ensuremath{\rho}}_{xx}(H)$, Hall effect ${\ensuremath{\rho}}_{xy}(H)$, and an electrolyte gating thin (100 nm) exfoliated $\mathrm{WT}{\mathrm{e}}_{2}$. observe...

Three-dimensional relaxation of small crystallites was imaged in real time using variable-temperature scanning tunneling microscopy. The micron-sized Pb crystallites, supported on Ru(0001), were equilibrated at 500--550 K, and the volume-preserving shape induced by a rapid temperature decrease to 353--423 K. (111) facet top crystallite grows sequential peeling single atomic layers, which shrink like circular islands. rate layer slows dramatically as new final state is reached.

The dependence of supramolecular structure on fractional molecular coverage has been investigated for acridine-9-carboxylic acid (ACA) and the C60:ACA binary system. coverage-dependent phase diagram ACA is first determined from room-temperature STM imaging. At low coverages (θ < 0.4 ML, ML = monolayer), forms a 2-D gas phase. Ordered structures appear with increasing coverage: chain composed molecules linked by consecutive O−H···N hydrogen bonds > ML), then dimer dimers paired...

Pentacene deposited onto a Ag(111) surface at 300 K is studied using scanning tunneling microscopy temperatures of and 50 K, providing structural insight into its unusual growth habit. At room temperature, an unexpectedly high pentacene coverage needed to nucleate ordered islands, which appear surrounded by disordered phase. These temperature nuclei are revealed as bilayer structures from their coverage-dependent size evolution molecularly resolved images domain boundaries, recorded K. this...

We have demonstrated a method for fabricating C60 overlayers with controlled spacing and chirality by reactive coadsorption the aromatic molecule acridine-9-carboxylic acid (ACA). Structural control is achieved mismatched symmetries of coadsorbates, as well specific intermolecular adsorbate-substrate interactions. The resulting supramolecular structure has period nearly three times large normal 2D packing 1 nm exists in enantiopure domains robust chirality.

The adsorption and molecular architecture of titanyl phthalocyanine (TiOPc) monolayer films on Ag (111) have been studied with scanning tunneling microscopy. Depending deposition flux, TiOPc selectively forms three distinct ordered structures. At lower (<0.1 ML/min) fluxes, molecules assemble into a well-ordered (2√13 × 2√13)R13.9°honeycomb phase comprised interlocked pairs. This pairing effectively reduces the repulsion between intrinsic dipole enhances attraction aromatic rings....

Controlled deposition of titanyl phthalocyanine (TiOPc) on Ag(111) produces a honeycomb monolayer phase consisting TiOPc molecules with two distinctive tilt angles. This periodic arrangement polar is used to direct C(70) growth into low-density 3D films novel kagome lattice arrangements. Structural models for the are determined from layer-by-layer scanning tunneling microscopy images and related dipolar template C(70)'s anisotropic polarizability. Molecular templates designed electrostatic...

Continuous silver films of nanometer thickness, grown at room temperature on $(7\ifmmode\times\else\texttimes\fi{}7)\ensuremath{-}\mathrm{Si}(111),$ display a wormlike morphology and thermally decay into isolated three-dimensional crystallites. We have tracked the dewetting process in real time using variable-temperature scanning tunneling microscopy. In this ultrathin regime, range transitional morphologies are observed, dependent substrate step density, annealing temperature. Initial film...

The ultrafast dynamics at a well-characterized $\text{CuPc}/{\text{C}}_{60}$ organic photovoltaic heterojunction have been directly measured with time-resolved two-photon photoemission (TR-2PPE). Phthalocyanine/${\text{C}}_{60}$ donor-acceptor interfaces, characterized in detail via scanning tunneling microscopy, provide model systems for studies of critical charge separation and recombination processes that determine device performance. TR-2PPE copper phthalocyanine...

The unoccupied electronic structure of C${}_{60}$ layers on Ag(111) was investigated with two-photon photoemission (2PPE) and scanning tunneling spectroscopy (STS). focus, in addition to providing level assignments for monolayers, is identifying signatures superatom molecular orbitals (SAMOs), diffuse levels weakly bound by the spherical potential fullerene shell, two complementary techniques. s-SAMO identified 3.3 eV above Fermi 2PPE at a bias 3.5 STS. Possible contributions from $p$-SAMO...

The molecular organization of a polar phthalocyanine, titanyl phthalocyanine (TiOPc), on the Ag(110) surface was studied with scanning tunneling microscopy (STM). In addition to intermolecular hydrogen bonding and electrostatic interactions that guide structure for nonpolar Pc's, we find evidence impact dipole layer TiOPc/Ag(110). TiOPc molecules adsorb tilted orientation contrasts flat-lying typically observed phthalocyanines. At highest coverages, consists neighboring opposing tilts. Close...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelf-Assembled .omega.-Hydroxyalkanethiol Monolayers with Internal Functionalities: Electrochemical and Infrared Structural Characterizations of Ether-Containing MonolayersKumar Sinniah, Jun Cheng, Samuel Terrettaz, Janice E. Reutt-Robey, Cary J. MillerCite this: Phys. Chem. 1995, 99, 39, 14500–14505Publication Date (Print):September 1, 1995Publication History Published online1 May 2002Published inissue 1 September...

Oxygen adsorption on Ag(110) was studied by ultrahigh vacuum scanning tunneling microscopy. Strong evidence that the n\ifmmode\times\else\texttimes\fi{}1),n=7,...,2, oxygen overlayers adopt an ``added-row'' structure similar to (2\ifmmode\times\else\texttimes\fi{}1)-O/Cu(110) system is presented. Since ``added row'' a -Ag-O-Ag- chainlike atop original substrate, source of substrate atoms must exist. Steps, in principle, serve as efficient these atoms, provided detachment rates from step...

Photoelectron spectroscopy was used to explore changes in Fermi level alignment, within the pi-pi* gap, arising from modifications coupling chemistry of conjugated phenylene ethynylene oligomers Au surface. Self-assembled monolayers were formed employing either thiol (4,4'-ethynylphenyl-1-benzenethiol or OPE-T) isocyanide (4,4'-ethynylphenyl-1-benzeneisocyanide OPE-NC) coupling. The electronic density states valence region two systems are nearly identical with exception a shift higher...

The adsorption of ${\mathrm{C}}_{60}$ on a bilayer film pentacene Ag(111) is studied with scanning tunneling microscopy and spectroscopy. At low coverage, molecules form extended linear structures due to the templating effect bilayer. in chains adsorb at bridge sites between two neighboring molecules. transport gap chain measured be $4.5\ifmmode\pm\else\textpm\fi{}0.2\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ using constant-current distance-voltage magnitude correlated uniquely coordination...

Scanning tunneling microscopy observations of the initial growth stages first layer pentacene on a monolayer film C60 Ag(111) are presented. Pentacene films nucleate and grow with molecules standing up at pentacene:C60 interface similar to thin phases observed weakly interacting substrates such as SiO2. Unlike reported phases, those 1 C60/Ag(111) exhibit striated morphology domains 4 nm nominal width. This long range pattern periodic displacements relative substrate is response stress...