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Stress waveforms applied to microbatteries induce current transients with a power-law decay that signals stress., Energy storage science calls for techniques to elucidate ion transport over a range of conditions and scales. We introduce a new technique, pascalammetry, in which stress is applied to a solid-state electrochemical device and induced faradaic current transients are measured and analyzed. Stress-step pascalammetry measurements are performed on operando microbattery probes (Li2O/Li/W) and Si cathodes, revealing stress-assisted Li+ diffusion. We show how non-Cottrellian lithium diffusional kinetics indicates stress, a prelude to battery degradation. An analytical solution to a diffusion/activation equation describes this stress signature, with spatiotemporal characteristics distinct from Cottrell’s classic solution for unstressed systems. These findings create an unprecedented opportunity for quantitative detection of stress in solid-state batteries through the current signature. Generally, pascalammetry offers a powerful new approach to study stress-related phenomena in any solid-state electrochemical system.

A carbon-nanotube-enabling scanning probe technique/nanotechnology for manipulating and measuring lithium at the nano/mesoscale is introduced. Scanning Li-nanopipette and probe microscopy (SLi-NPM) is based on a conductive atomic force microscope (AFM) cantilever with an open-ended multi-walled carbon nanotube (MWCNT) affixed to its apex. SLi-NPM operation is demonstrated with a model system consisting of a Li thin film on a Si(111) substrate. By control of bias, separation distance, and contact time, attograms of Li can be controllably pipetted to or from the MWCNT tip. Patterned surface Li features are then directly probed via noncontact AFM measurements with the MWCNT tip. The subsequent decay of Li features is simulated with a mesoscale continuum model, developed here. The Li surface diffusion coefficient for a four (two) Li layer thick film is measured as D=8(±1.2)×10(-15) cm(2) s(-1) (D=1.75(±0.15)×10(-15) cm(2) s(-1)). Dual-Li pipetting/measuring with SLi-NPM enables a broad range of time-dependent Li and nanoelectrode characterization studies of fundamental importance to energy-storage research.

We report an ultrahigh vacuum scanning tunneling microscopy study of thermally driven interface rearrangement in binary films of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and zinc phthalocyanine (ZnPc), a model electron acceptor–electron donor system for organic solar cells. Neat PCBM films have been previously shown to undergo a transition from a disordered (glassy) phase to a crystalline hexagonal close-packed (hcp) arrangement above a critical packing density of 0.9 molecules/nm2. We now show how local PCBM density has a critical impact on binary film structure evolution. Bilayer films of PCBM and ZnPc undergo a spontaneous vertical phase separation to PCBM/ZnPc/Au(111) stacking at lower (

Molecular interfaces have been prepared in titanyl phthalocyanine (TiOPc)–C60 monolayer films on Ag(111) and characterized with ultra high vacuum–scanning tunneling microscopy. Two distinct TiOPc monolayer phases, namely, a hexagonal phase and a honeycomb phase, were first generated as molecular-film substrates for C60 growth. Both TiOPc monolayer structures rearrange upon C60 adsorption, yielding films with nanophase-separated TiOPc and C60 domains and a new cocrystalline TiOPc2(C60)1 honeycomb network. Kinetic access to the cocrystalline network is most facile from the hexagonal TiOPc monolayer, producing extended domains. Detailed models for emergent structural phases and molecular interfaces are presented. Mechanisms for C60-induced rearrangements are developed from coverage-dependent measurements.

Pentacene deposited onto a Ag(111) surface at 300 K is studied using scanning tunneling microscopy at temperatures of 300 and 50 K, providing structural insight into its unusual growth habit. At room temperature, an unexpectedly high pentacene coverage is needed to nucleate ordered pentacene islands, which appear surrounded by a disordered pentacene phase. These room temperature pentacene nuclei are revealed as bilayer structures from their coverage-dependent size evolution and molecularly resolved images of domain boundaries, recorded at 50 K. At this reduced temperature, two different monolayer phases with long-range order and commensurate with the Ag(111) surface lattice further emerge. These two monolayer phases exhibit comparable (0.7 vs 0.8 molecule/nm2) packing densities, but distinct intermolecular registration and alignment with respect to the silver sublattice.

The adsorption and molecular architecture of titanyl phthalocyanine (TiOPc) monolayer films on Ag (111) have been studied with scanning tunneling microscopy. Depending on deposition flux, TiOPc selectively forms three distinct ordered monolayer structures. At lower (

A nonlocal Hall bar geometry is used to detect neutral-current Hall effects in graphene on silicon dioxide. Disorder is tuned by the addition of $\mathrm{Au}$ or $\mathrm{Ir}$ adatoms in ultrahigh vacuum. A reproducible neutral-current Hall effect is found in both as-fabricated and adatom-decorated graphene. The Hall angle exhibits a complex but reproducible dependence on gate voltage and disorder, and notably breaks electron-hole symmetry. An exponential dependence on length between Hall and inverse Hall probes indicates a neutral-current relaxation length of approximately $300\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$. The short relaxation length and lack of precession in a parallel magnetic field suggest that the neutral currents are valley currents. No signature of the spin-orbit coupling induced spin Hall effect is observed in the $\mathrm{Au}$- or $\mathrm{Ir}$-decorated graphene. The near lack of temperature dependence from 7 to 300 K is unprecedented among reports of valley Hall effect in graphene, and promising for using controlled disorder for room temperature neutral-current electronics.

Graphene decorated with 5d transitional metal atoms is predicted to exhibit many intriguing properties; for example iridium adatoms are proposed to induce a substantial topological gap in graphene. We extensively investigated the conductivity of single-layer graphene decorated with iridium deposited in ultra-high vacuum at low temperature (7 K) as a function of Ir concentration, carrier density, temperature and annealing conditions. Our results are consistent with the formation of Ir clusters of ~100 atoms at low temperature, with each cluster donating a single electronic charge to graphene. Annealing graphene increases the cluster size, reducing the doping and increasing the mobility. We do not observe any sign of an energy gap induced by spin-orbit coupling, possibly due to the clustering of Ir.

Scanning tunneling microscopy has proven to be a very powerful method for real space imaging of molecules on surfaces. Here we demonstrate how the morphological and chemical structure of the tunneling tip alters the apparent topography of STM images. When imaged with conventional W tips, isolated aluminum hydride (alane) oligomers appear as 2.8 A protrusions on Al(111). When imaged with alane-terminated tips, STM image contrast is both enhanced and inverted, with alane oligomers appearing as depressions. We attribute this image reversal to the electronic levels of tip-adsorbed alanes, whose distance from the surface Fermi levels reduces the coherence in the tunneling junction. The absence of a bias dependence in these images suggests predominant tunneling through tip-alane LUMO states.

The unoccupied electronic structure of C${}_{60}$ layers on Ag(111) was investigated with two-photon photoemission (2PPE) and scanning tunneling spectroscopy (STS). The focus, in addition to providing unoccupied level assignments for C${}_{60}$ monolayers, is on identifying signatures of C${}_{60}$ superatom molecular orbitals (SAMOs), diffuse unoccupied levels weakly bound by the spherical potential of the fullerene shell, in the two complementary techniques. The s-SAMO is identified 3.3 eV above the Fermi level in 2PPE and at a bias of 3.5 eV in STS. Possible contributions from $p$-SAMO levels are also discussed for both measurement techniques. The results are compared with recent low-temperature scanning tunneling microscopy (LT-STM) work that investigated C${}_{60}$ SAMOs on Cu(111) and oxygen-covered Cu(110) surfaces and with previous 2PPE measurements for C${}_{60}$ monolayers on Au(111) and Cu(111).

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 studies of copper phthalocyanine $(\text{CuPc})/{\text{C}}_{60}$ interfaces reveal ultrafast charge separation and provide evidence for recombination via low-lying CuPc triplet levels.

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, a range of transitional morphologies are observed, dependent on the substrate step density, annealing time and temperature. Initial film morphology is modulated by the underlying step structure and the growing crystallites show a corresponding step-induced deformation. During the initial stages of dewetting, the Ag-denuded areas transform to the $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30\ifmmode^\circ\else\textdegree\fi{}\ensuremath{-}\mathrm{A}\mathrm{g}/\mathrm{S}\mathrm{i}(111)$ surface, and spatially nonuniform denuded zones appear around the growing crystallites. Enhanced dewetting rates are observed in areas of lower step density, largely because steps act as kinetic obstacles. A simple form to relate the energy gain in dewetting to the density of crystallographic steps is provided. On preprepared $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30\ifmmode^\circ\else\textdegree\fi{}\ensuremath{-}\mathrm{A}\mathrm{g}/\mathrm{S}\mathrm{i}(111)$ substrates, dewetting occurs spontaneously even at room temperature.

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

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 relaxation was induced by a rapid temperature decrease to 353– 423 K. The (111) facet at the top of the crystallite grows by sequential peeling of single atomic layers, which shrink like circular islands. The rate of layer peeling slows dramatically as a new final state is reached.

Thin films of metal phthalocyanine (MPc) are grown on an Au(111) support with a newly developed aerosol molecular beam deposition source and characterized in situ via ultrahigh vacuum scanning tunneling microscopy. MPcs are delivered to Au(111) in a series of N2-entrained microsized solvent droplets of variable surface residence time. Phthalocyanine film registration to the herringbone reconstruction of the Au(111) surface, indicative of thermodynamically favored structure, is observed at submonolayer coverages for aromatic solvents with long residence times. Aerosol-deposited monolayer film structures are noncrystalline with tilted MPc orientations and vacancy nanocavities. Upon annealing, MPc molecules adopt flat-lying orientations with respect to the substrate and vacancies are eliminated. Film morphologies indicate solvation-mediated film nucleation and growth, with less long-range ordering that in vapor-generated films.

Step fluctuations on Ag(110) surfaces have been investigated with STMT atomic events that underlie these thermal fluctuations are quantified using a Langevin analysis. From the t1- scaling of the step-position correlation function, we deduce random attachment and detachment processes along the step edge, with a characteristic interval of 350 ms between successive detachments. Upon oxygen adsorption on vicinal Ag(110), a dramatic change in step configuration occurs. Steps which are originally equi-spaced due to repulsive step-step interactions are compressed into bunches. This process is driven by the formation of large (110) facets, on which oxygen atoms arrange into chains along [001]. The faceting dynamics are sensitive to the orientation of the step edge: proceeding by nucleation for close-packed steps and by spinodal decomposition for steps at an acute angle to the oxygen chains. A closer inspection of these oxygen chains reveals that each incorporates an additional row of silver atoms. When oxygen dosing pressures are kept below 10-6 Torr, silver atoms detaching from the step edge provide a sufficient supply necessary for the formation of the added row. With higher oxygen pressures, the silver atoms required for the oxygen chains are extracted directly from the terraces, resulting in the formation of large, long-lived etch pits.

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

We describe the design of a novel low‐profile valve to isolate a molecular beam source from an ultrahigh vacuum system. The valve thickness is simply the thickness of a standard double‐sided Conflat flange, on which the valve gate and actuation mechanism are assembled in a fully recessed configuration. The valve gate can accommodate a skimmer and/or several source collimating apertures. The manual actuator is mounted radial to the Conflat flange.

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 a rapid dose of a periodically stepped Pt(111) crystal face to a low total coverage of CO (\ensuremath{\sim}0.006 monolayer), the time evolution of CO molecules migrating from terrace to step sites was monitored with a temporal resolution as fast as 5 msec. When compared with a simple kinetic model, the data reveal statistical microscopic hopping rates for CO diffusion on the (111) plane over the $T=95\ensuremath{-}195$ K range investigated.