pyMSER─An Open-Source Library for Automatic Equilibration Detection in Molecular Simulations.

Automated molecular simulations are used extensively for predicting material properties. Typically, these simulations exhibit two regimes: a dynamic equilibration part, followed by a steady state. For extracting observable properties, the simulations must first reach a steady state so that thermodynamic averages can be taken.

Enhanced carbon dioxide drainage observed in digital rock under intermediate wetting conditions.

Carbon dioxide (CO ) trapping in capillary networks of reservoir rocks is a pathway to long-term geological storage. At pore scale, CO drainage displacement depends on injection pressure, temperature, and the rock's interaction with the surrounding fluids. Modeling this interaction requires adequate representations of both capillary volume and surface.

Full scale, microscopically resolved tomographies of sandstone and carbonate rocks augmented by experimental porosity and permeability values.

We report a dataset containing full-scale, 3D images of rock plugs augmented by petrophysical lab characterization data for application in digital rock and capillary network analysis. Specifically, we have acquired microscopically resolved tomography datasets of 18 cylindrical sandstone and carbonate rock samples having lengths of 25.4 mm and diameters of 9.

CRAFTED: An exploratory database of simulated adsorption isotherms of metal-organic frameworks.

Grand Canonical Monte Carlo is an important method for performing molecular-level simulations and assisting the study and development of nanoporous materials for gas capture applications. These simulations are based on the use of force fields and partial charges to model the interaction between the adsorbent molecules and the solid framework. The choice of the force field parameters and partial charges can significantly impact the results obtained, however, there are very few databases available to support a comprehensive impact evaluation.

Quantum Informed Machine-Learning Potentials for Molecular Dynamics Simulations of CO's Chemisorption and Diffusion in Mg-MOF-74.

Among various porous solids for gas separation and purification, metal-organic frameworks (MOFs) are promising materials that potentially combine high CO uptake and CO/N selectivity. So far, within the hundreds of thousands of MOF structures known today, it remains a challenge to computationally identify the best suited species. First principle-based simulations of CO adsorption in MOFs would provide the necessary accuracy; however, they are impractical due to the high computational cost.

Micro-computed tomography of sandstone rocks: Raw, filtered and segmented datasets.

High-resolution computed micro-tomography is an important area of science, which correlates well with several experimental methodologies and serves as a basis for advanced computational physics studies, in which high-resolution images are used as input to different scientific simulation models. The dataset presented herein includes (raw) grayscale images obtained using the Bruker Skyscan 1272 X-Ray tomograph; filtered images acquired through contrast enhancement and noise reduction filters; and segmented images obtained by using the IsoData segmentation method. All images have a resolution of 2.

High accuracy capillary network representation in digital rock reveals permeability scaling functions.

Permeability is the key parameter for quantifying fluid flow in porous rocks. Knowledge of the spatial distribution of the connected pore space allows, in principle, to predict the permeability of a rock sample. However, limitations in feature resolution and approximations at microscopic scales have so far precluded systematic upscaling of permeability predictions.

Graphene-enabled and directed nanomaterial placement from solution for large-scale device integration.

Directed placement of solution-based nanomaterials at predefined locations with nanoscale precision limits bottom-up integration in semiconductor process technology. We report a method for electric-field-assisted placement of nanomaterials from solution by means of large-scale graphene layers featuring nanoscale deposition sites. The structured graphene layers are prepared via either transfer or synthesis on standard substrates, and then are removed once nanomaterial deposition is completed, yielding material assemblies with nanoscale resolution that cover surface areas >1 mm.

A Platform for Analysis of Nanoscale Liquids with an Array of Sensor Devices Based on Two-Dimensional Material.

Analysis of nanoscale liquids, including wetting and flow phenomena, is a scientific challenge with far reaching implications for industrial technologies. We report the conception, development, and application of an integrated platform for the experimental characterization of liquids at the nanometer scale. The platform combines the functionalities of a two-dimensional electronic array of sensor devices with in situ application of highly sensitive optical microspectroscopy and atomic force microscopy.

Adsorption energy as a metric for wettability at the nanoscale.

Wettability is the affinity of a liquid for a solid surface. For energetic reasons, macroscopic drops of liquid form nearly spherical caps. The degree of wettability is then captured by the contact angle where the liquid-vapor interface meets the solid-liquid interface.

Two dimensional, electronic particle tracking in liquids with a graphene-based magnetic sensor array.

The investigation and control of liquid flow at the nanometer scale is a key area of applied research with high relevance to physics, chemistry, and biology. We introduce a method and a device that allows the spatial resolution of liquid flow by integrating an array of graphene-based magnetic (Hall) sensors that is used for tracking the movement of magnetic nanoparticles immersed in a liquid under investigation. With a novel device concept based on standard integration processes and experimentally verified material parameters, we numerically simulate the performance of a single sensor pixel, as well as the whole sensor array, for tracking magnetic nanoparticles having typical properties.

Power Dissipation and Electrical Breakdown in Black Phosphorus.

We report operating temperatures and heating coefficients measured in a multilayer black phosphorus device as a function of injected electrical power. By combining micro-Raman spectroscopy and electrical transport measurements, we have observed a linear temperature increase up to 600 K at a power dissipation rate of 0.896 K μm(3)/mW.

Hot spot dynamics in carbon nanotube array devices.

We report on the dynamics of spatial temperature distributions in aligned semiconducting carbon nanotube array devices with submicrometer channel lengths. By using high-resolution optical microscopy in combination with electrical transport measurements, we observe under steady state bias conditions the emergence of time-variable, local temperature maxima with dimensions below 300 nm, and temperatures above 400 K. On the basis of time domain cross-correlation analysis, we investigate how the intensity fluctuations of the thermal radiation patterns are correlated with the overall device current.

Black phosphorus photodetector for multispectral, high-resolution imaging.

Black phosphorus is a layered semiconductor that is intensely researched in view of applications in optoelectronics. In this letter, we investigate a multilayer black phosphorus photodetector that is capable of acquiring high-contrast (V > 0.9) images both in the visible (λVIS = 532 nm) as well as in the infrared (λIR = 1550 nm) spectral regime.

Spatially resolved electrostatic potential and photocurrent generation in carbon nanotube array devices.

We have used laser-excited photocurrent microscopy to map the internal electrostatic potential profile of semiconducting single-walled carbon nanotube (S-SWCNT) array devices with a spatial resolution of 250 nm. The measurements of S-SWCNTs on optically transparent samples provide new insights into the physical principles of device operation and reveal performance-limiting local heterogeneities in the electrostatic potential profile not observable with other imaging techniques. The experiments deliver photocurrent images from the underside of the S-SWCNT-metal contacts and thus enable the direct measurement of the charge carrier transfer lengths at the palladium-S-SWCNT and aluminum-S-SWCNT interfaces.

Light-matter interaction in a microcavity-controlled graphene transistor.

Graphene has extraordinary electronic and optical properties and holds great promise for applications in photonics and optoelectronics. Demonstrations including high-speed photodetectors, optical modulators, plasmonic devices, and ultrafast lasers have now been reported. More advanced device concepts would involve photonic elements such as cavities to control light-matter interaction in graphene.

Antenna-enhanced photocurrent microscopy on single-walled carbon nanotubes at 30 nm resolution.

We present the first photocurrent measurements along single carbon nanotube (CNT) devices with 30 nm resolution. Our technique is based on tip-enhanced near-field optical microscopy, exploiting the plasmonically enhanced absorption controlled by an optical nanoantenna. This allows for imaging of the zero-bias photocurrent caused by charge separation in local built-in electric fields at the contacts and close to charged particles that cannot be resolved using confocal microscopy.

The graphene-gold interface and its implications for nanoelectronics.

We combine optical microspectroscopy and electronic measurements to study how gold deposition affects the physical properties of graphene. We find that the electronic structure, the electron-phonon coupling, and the doping level in gold-plated graphene are largely preserved. The transfer lengths for electrons and holes at the graphene-gold contact have values as high as 1.

The polarized carbon nanotube thin film LED.

We demonstrate a light emitting p-i-n diode made of a highly aligned film of separated (99%) semiconducting carbon nanotubes, self-assembled from solution. By using a split gate technique, we create p- and n-doped regions in the nanotube film that are separated by a micron-wide gap. We inject p- and n-type charge carriers into the device channel from opposite contacts and investigate the radiative recombination using optical micro-spectroscopy.

Thermal infrared emission from biased graphene.

The high carrier mobility and thermal conductivity of graphene make it a candidate material for future high-speed electronic devices. Although the thermal behaviour of high-speed devices can limit their performance, the thermal properties of graphene devices remain incompletely understood. Here, we show that spatially resolved thermal radiation from biased graphene transistors can be used to extract the temperature distribution, carrier densities and spatial location of the Dirac point in the graphene channel.

Three-dimensional orientation of single molecules in a tunable optical lambda/2 microresonator.

A tightly focused radially polarized laser beam forms an unusual bimodal field distribution in an optical lambda/2-microresonator. We use a single-molecule dipole to probe the vector properties of this field distribution by tuning the resonator length with nanometer precision. Comparing calculated and experimental excitation patterns provides the three-dimensional orientation of the single-molecule dipole in the microresonator.

Carbon nanotube photo- and electroluminescence in longitudinal electric fields.

The photoluminescence of a partially suspended, semiconducting carbon nanotube that forms the active channel of a field-effect transistor is quenched and red-shifted upon application of a longitudinal electrical (source-drain) field. The quenching can be explained by a loss of oscillator strength and an increased Auger-like nonradiative decay of the E(11) exciton. The spectral shifts are due to drain-field-induced doping that leads to enhanced dielectric screening.

Efficient narrow-band light emission from a single carbon nanotube p-n diode.

Electrically driven light emission from carbon nanotubes could be used in nanoscale lasers and single-photon sources, and has therefore been the focus of much research. However, high electric fields and currents have either been necessary for electroluminescence, or have been an undesired side effect, leading to high power requirements and low efficiencies. Furthermore, electroluminescent linewidths have been broad enough to obscure the contributions of individual optical transitions.

Gate-variable light absorption and emission in a semiconducting carbon nanotube.

We investigate the gate field dependence of light absorption and emission of an individual, suspended semiconducting carbon nanotube using Raman and photoluminescence spectroscopies. We find a strong reduction in the absorption strength and a red shift of the E(33) state of the nanotube with increasing gate field. The photoluminescence from the E(11) state is quenched even stronger.

Phonon populations and electrical power dissipation in carbon nanotube transistors.

Carbon nanotubes and graphene are candidate materials for nanoscale electronic devices. Both materials show weak acoustic phonon scattering and long mean free paths for low-energy charge carriers. However, high-energy carriers couple strongly to optical phonons, which leads to current saturation and the generation of hot phonons.