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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Quantum dot microscope apparatus comprising a nanoscale semiconductor on the tip of a fiber, a tunneling electrical lead and a capacitive electrical lead on the fiber

A quantum dot microscope apparatus is provided. A further aspect employs a tilted or tapered end or tip on a microscopic probe. Another aspect of the present apparatus employs a probe including a quantum dot with only one tunneling lead connected to a power source. A manufacturing aspect includes creating a tapered or asymmetrically shaped specimen-facing end of a probe where a quantum dot is located on the end. A further manufacturing aspect includes using focused ion-beam milling to create a tip or end of a quantum dot microscope probe.

Tessmer, Stuart Holden↗
DOE OSTI2013

Pushing the limits: characterisation and performance of the prototype multilayer Laue lenses fluorescence microscope with a view to achieve nm-scale spatial resolution

Synchrotron based x-ray microscopy established itself as a prominent tool for noninvasive investigations in many areas of science and technology. Many facilities around the world routinely achieve sub-micrometer resolution with a few instruments capable of imaging with the spatial resolution better than 100 nm. With an ongoing effort to push the 2D/3D resolution down to 10 nm in the hard x-ray regime both fabrication of the nano-focusing optics and stability of a microscope become extremely challenging. In this work we present our approach to overcome technical challenges on the path towards high spatial resolution hard x-ray microscopy and demonstrate the performance of a scanning fluorescence microscope equipped with the multilayer Laue lenses focusing optics. We utilised the Imaging and Coherence beamline (I13) at Diamond Light Source to perform X-ray testing of the scanning microscope.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Avoided Level Crossing and Entangled States of Interacting Hydrogen Molecules Detected by the Quantum Superposition Microscope

Pump–probe measurements by ultrashort THz pulses can be used to excite and follow the coherence dynamics in the time domain of single hydrogen molecules (H 2 ) in the junction of a scanning tunneling microscope (STM). By tailoring the resonance frequency through the sample bias, we identified two spectral signatures of the interactions among multiple H 2 molecules. First, the avoided level crossing featured by energy gaps ranging from 20 to 80 GHz was observed because of the level repulsion between two H 2 molecules. Second, the tip can sense the signal of H 2 outside the junction through the projective measurement on the H 2 inside the junction, owing to the entangled states created through the interactions. A dipolar-type interaction was integrated into the tunneling two-level system model of H 2 , enabling accurate reproduction of the observed behaviors. Furthermore, our results obtained by the quantum superposition microscope reveal the intricate quantum mechanical interplay among H 2 molecules and additionally provide a 2D platform to investigate unresolved questions of amorphous materials.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Measurement of Semiconductor Surface Potential using the Scanning Electron Microscope

We calibrate the secondary electron signal from a standard scanning electron microscope to voltage, yielding an image of the surface or near-surface potential. Data on both atomically abrupt heterojunction GaInP/GaAs and diffused homojunction Si solar cell devices clearly show the expected variation in potential with position and applied bias, giving depletion widths and locating metallurgical junctions to an accuracy better than 10 nm. In some images, distortion near the p-n junction is observed, seemingly consistent with the effects of lateral electric fields (patch fields). Reducing the tube bias removes this distortion. This approach results in rapid and straightforward collection of near-surface potential data using a standard scanning electron microscope.

14 SOLAR ENERGY↗
DOE OSTI2011

Calibration of the Modulation Transfer Function of Surface Profilometers with Binary Pseudorandom Test Standards: Expanding the Application Range to Fizeau Interferometers and Electron Microscopes

A modulation transfer function (MTF) calibration method based on binary pseudorandom (BPR) gratings and arrays has been proven to be an effective MTF calibration method for interferometric microscopes and a scatterometer. Here we report on a further expansion of the application range of the method. We describe the MTF calibration of a 6 in. phase shifting Fizeau interferometer. Beyond providing a direct measurement of the interferometer's MTF, tests with a BPR array surface have revealed an asymmetry in the instrument's data processing algorithm that fundamentally limits its bandwidth. Moreover, the tests have illustrated the effects of the instrument's detrending and filtering procedures on power spectral density measurements. The details of the development of a BPR test sample suitable for calibration of scanning and transmission electron microscopes are also presented. Such a test sample is realized as a multilayer structure with the layer thicknesses of two materials corresponding to the BPR sequence. The investigations confirm the universal character of the method that makes it applicable to a large variety of metrology instrumentation with spatial wavelength bandwidths from a few nanometers to hundreds of millimeters.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Microscopic diffusion in hydrated encysted eggs of brine shrimp

We have studied microscopic diffusion of water in fully hydrated encysted eggs of brine shrimp (Artemia). We utilized quasielastic neutron scattering. Dry eggs of brine shrimp were rehydrated using (1) water without additives, (2) eutectic mixture of water and dimethyl sulfoxide, and (3) a concentrated aqueous solution of lithium chloride. Despite the complexity of the hydrated multicellular organism, measurable microscopic diffusivity of water is rather well defined. Pure hydration water in eggs exhibits freezing temperature depression, whereas hydration water in eggs mixed with dimethyl sulfoxide or lithium chloride does not crystallize at all. The characteristic size of the voids occupied by water or aqueous solvents in hydrated brine shrimp eggs is between 2 and 10 nm. Those voids are accessible to co-solvents such as dimethyl sulfoxide and lithium chloride. There is no evidence of intracellular water in the hydrated eggs. The lack of intracellular water in the fully hydrated (but still under arrested development) state must be linked to the unique resilience against adverse environmental factors documented not only for the anhydrous, but also hydrated encysted eggs of brine shrimp.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Rotational positioning system adapted to atomic force microscope for measuring anisotropic surface properties

The diverse atomic configurations induce the anisotropic surface properties. For investigating anisotropic phenomena, we developed a rotational positioning system adapted to atomic force microscope (AFM). This rotational positioning system is applied to revolve the measured sample to defined angular direction, and it composed of an inertial rotational stepper and a visual angular measurement. The inertial rotational stepper with diameter 30 mm and height 7.6 mm can be easily attached to the AFM-system built in any general optical microscope. Based on a clearance less bearing and the inertial driving method, its bidirectional angular resolution reaches 0.005 deg. per step. For realizing a close-loop controlled angular positioning function, the visual measurement method is utilized. Through the feedback control, the angular positioning error is less than 0.01 deg. For verifying the system performance, we used it to investigate the anisotropic surface properties of graphite. Through a modified cantilever tip, the atomic-scale stick-slip, and the anisotropic friction phenomena can be distinctly detected.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Evaluation of gratings for X-ray and neutron phase imaging techniques by using x-ray projection microscope

In the X-ray and neutron Talbot (-Lau) interferometry, fabrication of phase or amplitude grating with a high-aspect ratio is a key factor to obtain high quality images. To improve the ability of the grating, evaluation of shape and thickness variation and feed-back to the fabrication process are essential. Here, it is shown that X-ray projection microscope with a spatial resolution of sub-micrometer is a powerful tool for the purpose. Three kinds of gratings have been evaluated by using a projection X-ray microscope with X-ray source size of 0.6 micrometer. Uniformity of thickness of the grating has been visualized nondestructively.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

Detection and measurement of electroreflectance on quantum cascade laser device using Fourier transform infrared microscope

We demonstrate the use of a Fourier Transform Infrared microscope system to detect and measure electroreflectance (ER) from mid-infrared quantum cascade laser (QCL) device. To characterize intersubband transition (ISBT) energies in a functioning QCL device, a microscope is used to focus the probe on the QCL cleaved mirror. The measured ER spectra exhibit resonance features associated to ISBTs under applied electric field in agreement with the numerical calculations and comparable to observed photocurrent, and emission peaks. The method demonstrates the potential as a characterization tool for QCL devices.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Resolving three-dimensional shape of sub-50 nm wide lines with nanometer-scale sensitivity using conventional optical microscopes

We experimentally demonstrate that the three-dimensional (3-D) shape variations of nanometer-scale objects can be resolved and measured with sub-nanometer scale sensitivity using conventional optical microscopes by analyzing 4-D optical data using the through-focus scanning optical microscopy (TSOM) method. These initial results show that TSOM-determined cross-sectional (3-D) shape differences of 30 nm–40 nm wide lines agree well with critical-dimension atomic force microscope measurements. The TSOM method showed a linewidth uncertainty of 1.22 nm (k = 2). Complex optical simulations are not needed for analysis using the TSOM method, making the process simple, economical, fast, and ideally suited for high volume nanomanufacturing process monitoring.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Electromagnetic model for near-field microwave microscope with atomic resolution: Determination of tunnel junction impedance

An electrodynamic model is proposed for the tunneling microwave microscope with subnanometer space resolution as developed by Lee et al. [Appl. Phys. Lett. 97, 183111 (2010)]. Tip-sample impedance Z{sub a} was introduced and studied in the tunneling and non-tunneling regimes. At tunneling breakdown, the microwave current between probe and sample flows along two parallel channels characterized by impedances Z{sub p} and Z{sub t} that add up to form overall impedance Z{sub a}. Quantity Z{sub p} is the capacitive impedance determined by the near field of the probe and Z{sub t} is the impedance of the tunnel junction. By taking into account the distance dependences of effective tip radius r{sub 0}(z) and tunnel resistance R{sub t}(z) = Re[Z{sub t}(z)], we were able to explain the experimentally observed dependences of resonance frequency f{sub r}(z) and quality factor Q{sub L}(z) of the microscope. The obtained microwave resistance R{sub t}(z) and direct current tunnel resistance R{sub t}{sup dc}(z) exhibit qualitatively similar behavior, although being largely different in both magnitude and the characteristic scale of height dependence. Interpretation of the microwave images of the atomic structure of test samples proved possible by taking into account the inductive component of tunnel impedance ImZ{sub t} = ωL{sub t}. Relation ωL{sub t}/R{sub t} ≈ 0.235 was obtained.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Secondary electron imaging of monolayer materials inside a transmission electron microscope

A scanning transmission electron microscope equipped with a backscattered and secondary electron detector is shown capable to image graphene and hexagonal boron nitride monolayers. Secondary electron contrasts of the two lightest monolayer materials are clearly distinguished from the vacuum level. A signal difference between these two materials is attributed to electronic structure differences, which will influence the escape probabilities of the secondary electrons. Our results show that the secondary electron signal can be used to distinguish between the electronic structures of materials with atomic layer sensitivity, enhancing its applicability as a complementary signal in the analytical microscope.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

A laboratory 8 keV transmission full-field x-ray microscope with a polycapillary as condenser for bright and dark field imaging

This article introduces a laboratory setup of a transmission full-field x-ray microscope at 8 keV photon energy. The microscope operates in bright and dark field imaging mode with a maximum field of view of 50 μm. Since the illumination geometry determines whether the sample is illuminated homogeneously and moreover, if different imaging methods can be applied, the condenser optic is one of the most significant parts. With a new type of x-ray condenser, a polycapillary optic, we realized bright field imaging and for the first time dark field imaging at 8 keV photon energy in a laboratory setup. A detector limited spatial resolution of 210 nm is measured on x-ray images of Siemens star test patterns.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

A single-cell scraper based on an atomic force microscope for detaching a living cell from a substrate

We describe an atomic force microscope (AFM) manipulator that can detach a single, living adhesion cell from its substrate without compromising the cell's viability. The micrometer-scale cell scraper designed for this purpose was fabricated from an AFM micro cantilever using focused ion beam milling. The homemade AFM equipped with the scraper was compact and standalone and could be mounted on a sample stage of an inverted optical microscope. It was possible to move the scraper using selectable modes of operation, either a manual mode with a haptic device or a computer-controlled mode. The viability of the scraped single cells was evaluated using a fluorescence dye of calcein-acetoxymethl ester. Single cells detached from the substrate were collected by aspiration into a micropipette capillary glass using an electro-osmotic pump. As a demonstration, single HeLa cells were selectively detached from the substrate and collected by the micropipette. It was possible to recultivate HeLa cells from the single cells collected using the system.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Improving z-tracking accuracy in the two-photon single-particle tracking microscope

Here, we present a method that can improve the z-tracking accuracy of the recently invented TSUNAMI (Tracking of Single particles Using Nonlinear And Multiplexed Illumination) microscope. This method utilizes a maximum likelihood estimator (MLE) to determine the particle's 3D position that maximizes the likelihood of the observed time-correlated photon count distribution. Our Monte Carlo simulations show that the MLE-based tracking scheme can improve the z-tracking accuracy of TSUNAMI microscope by 1.7 fold. In addition, MLE is also found to reduce the temporal correlation of the z-tracking error. Taking advantage of the smaller and less temporally correlated z-tracking error, we have precisely recovered the hybridization-melting kinetics of a DNA model system from thousands of short single-particle trajectories in silico. Our method can be generally applied to other 3D single-particle tracking techniques.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Development of a detachable high speed miniature scanning probe microscope for large area substrates inspection

We have developed a high speed, miniature scanning probe microscope (MSPM) integrated with a Positioning Unit (PU) for accurately positioning the MSPM on a large substrate. This combination enables simultaneous, parallel operation of many units on a large sample for high throughput measurements. The size of the MSPM is 19 × 45 × 70 mm{sup 3}. It contains a one-dimensional flexure stage with counter-balanced actuation for vertical scanning with a bandwidth of 50 kHz and a z-travel range of more than 2 μm. This stage is mechanically decoupled from the rest of the MSPM by suspending it on specific dynamically determined points. The motion of the probe, which is mounted on top of the flexure stage is measured by a very compact optical beam deflection (OBD). Thermal noise spectrum measurements of short cantilevers show a bandwidth of 2 MHz and a noise of less than 15 fm/Hz{sup 1/2}. A fast approach and engagement of the probe to the substrate surface have been achieved by integrating a small stepper actuator and direct monitoring of the cantilever response to the approaching surface. The PU has the same width as the MSPM, 45 mm and can position the MSPM to a pre-chosen position within an area of 275×30 mm{sup 2} to within 100 nm accuracy within a few seconds. During scanning, the MSPM is detached from the PU which is essential to eliminate mechanical vibration and drift from the relatively low-resonance frequency and low-stiffness structure of the PU. Although the specific implementation of the MSPM we describe here has been developed as an atomic force microscope, the general architecture is applicable to any form of SPM. This high speed MSPM is now being used in a parallel SPM architecture for inspection and metrology of large samples such as semiconductor wafers and masks.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

A full-field transmission x-ray microscope for time-resolved imaging of magnetic nanostructures

Sub-nanosecond magnetization dynamics of small permalloy (Ni{sub 80}Fe{sub 20}) elements has been investigated with a new full-field transmission microscope at the soft X-ray beamline P04 of the high brilliance synchrotron radiation source PETRA III. The soft X-ray microscope generates a flat-top illumination field of 20 μm diameter using a grating condenser. A tilted nanostructured magnetic sample can be excited by a picosecond electric current pulse via a coplanar waveguide. The transmitted light of the sample plane is directly imaged by a micro zone plate with < 65 nm resolution onto a 2D gateable X-ray detector to select one particular bunch in the storage ring that probes the time evolution of the dynamic information successively via XMCD spectromicroscopy in a pump-probe scheme. In the experiments it was possible to generate a homogeneously magnetized state in patterned magnetic layers by a strong magnetic Oersted field pulse of 200 ps duration and directly observe the recovery to the initial flux-closure vortex patterns.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Development of a scanning transmission x-ray microscope for the beamline P04 at PETRA III DESY

We present a scanning transmission x-ray microscope (STXM) built on top of our existing modular platform for high resolution imaging experiments. This platform consists of up to three separate vacuum chambers and custom designed piezo stages. These piezo stages are able to move precisely in x-, y- and z-direction, this makes it possible to adjust the components for different imaging modes. During recent experiments the endstation was operated mainly as a transmission x-ray microscope (TXM) [1, 2].

43 PARTICLE ACCELERATORS↗