Showing papers on "Resolution (electron density) published in 2006"
TL;DR: A high-resolution fluorescence microscopy method based on high-accuracy localization of photoswitchable fluorophores that can, in principle, reach molecular-scale resolution is developed.
Abstract: We have developed a high-resolution fluorescence microscopy method based on high-accuracy localization of photoswitchable fluorophores. In each imaging cycle, only a fraction of the fluorophores were turned on, allowing their positions to be determined with nanometer accuracy. The fluorophore positions obtained from a series of imaging cycles were used to reconstruct the overall image. We demonstrated an imaging resolution of 20 nm. This technique can, in principle, reach molecular-scale resolution.
7,213 citations
TL;DR: In this paper, the authors exploit the dispersion characteristics of an anisotropic metamaterial crystal that is obliquely cut at its output plane, or has a curved output surface, in order to map the input field distribution onto the crystal's output surface with a compressed angular spectrum, resulting in a ''magnified'' image.
Abstract: Here we suggest and explore theoretically an idea for a far-field scanless optical microscopy with a subdiffraction resolution. We exploit the special dispersion characteristics of an anisotropic metamaterial crystal that is obliquely cut at its output plane, or has a curved output surface, in order to map the input field distribution onto the crystal's output surface with a compressed angular spectrum, resulting in a ``magnified'' image. This can provide a far-field imaging system with a resolution beyond the diffraction limits while no scanning is needed.
705 citations
TL;DR: In this article, the authors demonstrate x-ray diffraction imaging with high resolution in all three dimensions, as determined by a quantitative analysis of the reconstructed volume images, using no a priori knowledge about the shape or composition of the object, which has never before been demonstrated on a nonperiodic object.
Abstract: Coherent x-ray diffraction microscopy is a method of imaging nonperiodic isolated objects at resolutions limited, in principle, by only the wavelength and largest scattering angles recorded. We demonstrate x-ray diffraction imaging with high resolution in all three dimensions, as determined by a quantitative analysis of the reconstructed volume images. These images are retrieved from the three-dimensional diffraction data using no a priori knowledge about the shape or composition of the object, which has never before been demonstrated on a nonperiodic object. We also construct two-dimensional images of thick objects with greatly increased depth of focus (without loss of transverse spatial resolution). These methods can be used to image biological and materials science samples at high resolution with x-ray undulator radiation and establishes the techniques to be used in atomic-resolution ultrafast imaging at x-ray free-electron laser sources.
570 citations
TL;DR: Far-field fluorescence microscopy with a focal-plane resolution of 15-20 nm in biological samples is demonstrated, enabling an up to 30-fold increase in total fluorescence signal as compared with reported stimulated emission depletion illumination schemes.
Abstract: We demonstrate far-field fluorescence microscopy with a focal-plane resolution of 15–20 nm in biological samples. The 10- to 12-fold multilateral increase in resolution below the diffraction barrier has been enabled by the elimination of molecular triplet state excitation as a major source of photobleaching of a number of dyes in stimulated emission depletion microscopy. Allowing for relaxation of the triplet state between subsequent excitation–depletion cycles yields an up to 30-fold increase in total fluorescence signal as compared with reported stimulated emission depletion illumination schemes. Moreover, it enables the reduction of the effective focal spot area by up to ≈140-fold below that given by diffraction. Triplet-state relaxation can be realized either by reducing the repetition rate of pulsed lasers or by increasing the scanning speed such that the build-up of the triplet state is effectively prevented. This resolution in immunofluorescence imaging is evidenced by revealing nanoscale protein patterns on endosomes, the punctuated structures of intermediate filaments in neurons, and nuclear protein speckles in mammalian cells with conventional optics. The reported performance of diffraction-unlimited fluorescence microscopy opens up a pathway for addressing fundamental problems in the life sciences.
550 citations
TL;DR: The attainment of subdiffraction resolution using stimulated emission depletion (STED) microscopy with GFP-labeled samples is reported, marking the advent of nanoscale biological microscopeopy with genetically encoded markers.
Abstract: We report attainment of subdiffraction resolution using stimulated emission depletion (STED) microscopy with GFP-labeled samples. The approximately 70 nm lateral resolution attained in this study is demonstrated by imaging GFP-labeled viruses and the endoplasmic reticulum (ER) of a mammalian cell. Our results mark the advent of nanoscale biological microscopy with genetically encoded markers.
359 citations
TL;DR: A new detection scheme for Fourier domain optical coherence microscopy that exhibits high transverse resolution along an axially extended focal range is reported on.
Abstract: We report on a new detection scheme for Fourier domain optical coherence microscopy that exhibits high transverse resolution along an axially extended focal range. Nearly constant transverse resolution of ∼1.5 μm along a focal range of 200 μm is experimentally verified with a maximum sensitivity of 105 dB. A broad-bandwidth Ti:sapphire laser allowed for an axial resolution of 3 μm in air.
327 citations
TL;DR: This work re-examines the resolution problem by adopting a stochastic framework and presents a resolution measure that overcomes the limitations of Rayleigh's criterion and predicts that the resolution of optical microscopes is not limited and that it can be improved by increasing the number of detected photons.
Abstract: Rayleigh's criterion is extensively used in optical microscopy for determining the resolution of microscopes. This criterion imposes a resolution limit that has long been held as an impediment for studying nanoscale biological phenomenon through an optical microscope. However, it is well known that Rayleigh's criterion is based on intuitive notions. For example, Rayleigh's criterion is formulated in a deterministic setting that neglects the photon statistics of the acquired data. Hence it does not take into account the number of detected photons, which, in turn, raises concern over the use of Rayleigh's criterion in photon-counting techniques such as single-molecule microscopy. Here, we re-examine the resolution problem by adopting a stochastic framework and present a resolution measure that overcomes the limitations of Rayleigh's criterion. This resolution measure predicts that the resolution of optical microscopes is not limited and that it can be improved by increasing the number of detected photons. Experimental verification of the resolution measure is carried out by imaging single-molecule pairs with different distances of separation. The resolution measure provides a quantitative tool for designing and evaluating single-molecule experiments that probe biomolecular interactions.
276 citations
TL;DR: It is demonstrated that the technique of 3D-FSD can be successfully applied to increase the spatial resolution in a real IR imaging setup and a new computational procedure is presented which is suitable to improve the spatialresolution in IR imaging.
230 citations
TL;DR: A definition for the depth resolution for scanning transmission electron microscope depth sectioning is developed and initial results from this method are presented, including results from 3D imaging by optical sectioning of catalytic metal clusters and single atoms.
Abstract: The ability to correct the aberrations of the probe-forming lens in the scanning transmission electron microscope provides not only a significant improvement in transverse resolution but in addition brings depth resolution at the nanometer scale. Aberration correction therefore opens up the possibility of 3D imaging by optical sectioning. Here we develop a definition for the depth resolution for scanning transmission electron microscope depth sectioning and present initial results from this method. Objects such as catalytic metal clusters and single atoms on various support materials are imaged in three dimensions with a resolution of several nanometers. Effective focal depth is determined by statistical analysis and the contributing factors are discussed. Finally, current challenges and future capabilities available through new instruments are discussed.
210 citations
TL;DR: The concept of tilted optical pulses into diffraction and imaging techniques and the methodology experimentally are introduced and the potential of tilting the electron pulses themselves for applications in domains involving nuclear and electron motions are discussed.
Abstract: Ultrafast electron microscopy and diffraction are powerful techniques for the study of the time-resolved structures of molecules, materials, and biological systems. Central to these approaches is the use of ultrafast coherent electron packets. The electron pulses typically have an energy of 30 keV for diffraction and 100–200 keV for microscopy, corresponding to speeds of 33–70% of the speed of light. Although the spatial resolution can reach the atomic scale, the temporal resolution is limited by the pulse width and by the difference in group velocities of electrons and the light used to initiate the dynamical change. In this contribution, we introduce the concept of tilted optical pulses into diffraction and imaging techniques and demonstrate the methodology experimentally. These advances allow us to reach limits of time resolution down to regimes of a few femtoseconds and, possibly, attoseconds. With tilted pulses, every part of the sample is excited at precisely the same time as when the electrons arrive at the specimen. Here, this approach is demonstrated for the most unfavorable case of ultrafast crystallography. We also present a method for measuring the duration of electron packets by autocorrelating electron pulses in free space and without streaking, and we discuss the potential of tilting the electron pulses themselves for applications in domains involving nuclear and electron motions.
199 citations
TL;DR: In this paper, the spectroscopic photoemission and low energy electron microscope (SPELEEM) was used to demonstrate the spectro-microscopic capabilities of the beamline beamline at Elettra synchrotron facility.
Abstract: The instrumentation for synchrotron radiation X-ray photoemission electron microscopy (XPEEM) has recently undergone significant improvements, finding application in diverse fields such as magnetism, chemistry, surface science and nanostructure characterization. The spectroscopic photoemission and low energy electron microscope (SPELEEM) operational at the 'Nanospectroscopy beamline' at the Elettra synchrotron facility combines structural and spectroscopic analysis methods in a single instrument, exploiting the inherent chemical sensitivity of X rays. The SPELEEM reaches an energy resolution of 0.2 eV and a lateral resolution of few tens of nanometers in XPEEM. Selected results are used to illustrate the spectro-microscopic capabilities of the SPELEEM, and the usefulness of available complementary methods such as low energy electron microscopy (LEEM) and micro-spot low energy electron diffraction (LEED).
TL;DR: The DTEM as mentioned in this paper is a single-shot in situ transmission electron microscope (TEM) modified to drive material processes with a nanosecond laser, "pump" pulse and measure it shortly afterward with a 30-ns-long probe pulse of ∼107 electrons.
Abstract: A dynamic transmission electron microscope (DTEM) has been designed and implemented to study structural dynamics in condensed matter systems. The DTEM is a conventional in situ transmission electron microscope (TEM) modified to drive material processes with a nanosecond laser, “pump” pulse and measure it shortly afterward with a 30-ns-long probe pulse of ∼107 electrons. An image with a resolution of <20nm may be obtained with a single pulse, largely eliminating the need to average multiple measurements and enabling the study of unique, irreversible events with nanosecond- and nanometer-scale resolution. Space charge effects, while unavoidable at such a high current, may be kept to reasonable levels by appropriate choices of operating parameters. Applications include the study of phase transformations and defect dynamics at length and time scales difficult to access with any other technique. This single-shot approach is complementary to stroboscopic TEM, which is capable of much higher temporal resolution but is restricted to the study of processes with a very high degree of repeatability.
TL;DR: This work opens the door for nondestructive and quantitative imaging of 3D morphology and 3D internal structure of a wide range of materials at the nanometer scale resolution that are amorphous or possess only short-range atomic organization.
Abstract: In combination of direct phase retrieval of coherent x-ray diffraction patterns with a novel tomographic reconstruction algorithm, we, for the first time, carried out quantitative 3D imaging of a heat-treated GaN particle with each voxel corresponding to 17 x 17 x 17 nm3. We observed the platelet structure of GaN and the formation of small islands on the surface of the platelets, and successfully captured the internal GaN-Ga2O3 core shell structure in three dimensions. This work opens the door for nondestructive and quantitative imaging of 3D morphology and 3D internal structure of a wide range of materials at the nanometer scale resolution that are amorphous or possess only short-range atomic organization.
TL;DR: In this article, the authors achieved a resolution of 90 nm with a research microscope simply by replacing the standard bright field condenser with a home-built illumination system with a cardioid annular condenser.
Abstract: Resolution of 90 nm was achieved with a research microscope simply by replacing the standard bright-field condenser with a homebuilt illumination system with a cardioid annular condenser. Diffraction gratings with 100 nm width lines as well as less than 100 nm size features of different-shaped objects were clearly visible on a calibrated microscope test slide. The resolution increase results from a known narrower diffraction pattern in coherent illumination for the annular aperture compared with the circular aperture. This explanation is supported by an excellent accord of calculated and measured diffraction patterns for a 50 nm radius disk.
TL;DR: Aberration correction in scanning transmission electron microscopy has more than doubled the lateral resolution, greatly improving the visibility of individual impurity or dopant atoms, and depth resolution is increased five-fold, to the nanometer level.
TL;DR: A review of the recent approaches to generalized 2D correlation spectroscopy can be found in this article, where a brief introduction of GSP is described and a review of successful applications of new approaches to GSP are highlighted.
Abstract: This review is focused on the recent approaches to generalized 2D correlation spectroscopy, a technique widely used for the analysis of spectral data. A brief introduction of generalized 2D correlation spectroscopy is described first. Then the powerful combination of generalized 2D correlation spectroscopy and multivariate chemometircs techniques, such as the data reconstruction by principal component analysis (PCA), eigenvalue manipulation transformation (EMT), and self‐modeling curve resolution (SMCR) analysis are explored. Examples of successful applications of new approaches to generalized 2D correlation spectroscopy are highlighted.
TL;DR: This work employs a deuteration scheme in which individual methyl groups are selectively protonated, which allows the acquisition of proton carbon correlation spectra with a resolution comparable to that in solution-state NMR experiments.
Abstract: MAS solid-state NMR experiments applied to biological solids are still hampered by low sensitivity and resolution. In this work, we employ a deuteration scheme in which individual methyl groups are selectively protonated. This labeling scheme allows the acquisition of proton carbon correlation spectra with a resolution comparable to that in solution-state NMR experiments. We observe an increase in resolution by a factor of 10−15 compared to standard heteronuclear correlation experiments using PMLG for 1H,1H dipolar decoupling in the indirect dimension. At the same time, the full sensitivity of the proton-based experiment is retained. In comparison to the heteronuclear detected version of the experiment, a gain in sensitivity of a factor of approximately 4.7 is achieved.
TL;DR: In this paper, an energy-tunable transmission hard x-ray microscope with close to 60 nm spatial resolution in three dimensions (3D) has been developed with a cone beam illumination, a zone plate of 50 nm outmost zone width, and software feedback.
Abstract: An energy-tunable transmission hard x-ray microscope with close to 60 nm spatial resolution in three dimensions (3D) has been developed. With a cone beam illumination, a zone plate of 50 nm outmost zone width, a stable mechanical design, and software feedback, we obtained tomographic data sets that are close to 60 nm spatial resolution. Meanwhile, the element specific imaging was also obtained by a differential absorption contrast technique used below and above the absorption of the element. Examples of advanced intergraded circuit devices are used to demonstrate the element selectivity and spatial resolution in 3D of the microscope.
TL;DR: In this article, a hard x-ray transmission microscope with 30nm spatial resolution has been developed employing the third diffraction order of a zone plate objective, which utilizes a capillary type condenser with suitable surface figure to generate a hollow cone illumination.
Abstract: A hard x-ray transmission microscope with 30nm spatial resolution has been developed employing the third diffraction order of a zone plate objective. The microscope utilizes a capillary type condenser with suitable surface figure to generate a hollow cone illumination which is matched in illumination range to the numerical aperture of the third order diffraction of a zone plate with an outmost zone width of 50nm. Using a test sample of a 150nm thick gold spoke pattern with finest half-pitch of 30nm, the authors obtained x-ray images with 30nm resolution at 8keV x-ray energy.
TL;DR: With a novel phase filter, near-field images of single organic fluorophores were obtained with approximately sixfold improvement in the signal-to-noise ratio, thus demonstrating the first true Rayleigh resolution test for near- field images ofsingle molecules.
Abstract: We demonstrate apertureless near-field microscopy of single molecules at sub-10 nm resolution. With a novel phase filter, near-field images of single organic fluorophores were obtained with ~sixfold improvement in the signal-to-noise ratio. The improvement allowed pairs of molecules separated by ~15 nm to be reliably and repeatedly resolved, thus demonstrating the first true Rayleigh resolution test for near-field images of single molecules. The potential of this technique for biological applications was demonstrated with an experiment that measured the helical rise of A-form DNA.
TL;DR: In this paper, a 3D micro-particle tracking velocimetry (micro-PTV) scheme is presented using a single camera with deconvolution microscopy.
Abstract: A three-dimensional micro-particle tracking velocimetry (micro-PTV) scheme is presented using a single camera with deconvolution microscopy. This method devises tracking of the line-of-sight (z) flow vectors by correlating the diffraction pattern ring size variations with the defocusing distances of small particle locations. The working principle is based on optical serial sectioning microscopy, or equivalently deconvolution microscopy, that records images of an infinitesimally small particle, and generates a point-spread function of the three-dimensional diffraction patterns. A new image-processing algorithm has also been developed to digitally identify the center locations and measure the radii of the diffraction rings, which allows simultaneous tracking of all three-vector components. The developed PTV technique uses a 40×, 0.75 NA dry objective lens with 500-nm fluorescent seeding particles of SG=1.05, and successfully measures the fully three-dimensional fields flowing over a spherical obstacle snuggly fitted inside a 100 μm × 100 μm micro-channel. The volumetric measurement resolution of the present system is equivalent to a 5.16 μm × 5.16 μm × 5.16 μm cube, and the overall measurement uncertainty for single-point velocity vector detection is estimated to ±7.58%.
TL;DR: The ability to map and resolve specific vibrational modes with 30 nm spatial resolution for dielectric layers with different thicknesses is demonstrated, enabling chemically specific, subsurface imaging with high spatial resolution.
Abstract: We report on chemically specific, subsurface imaging with high spatial resolution. Using tip-enhanced Raman spectroscopy, we probe carbon nanotubes buried beneath a host dielectric media. We demonstrate our ability to map and resolve specific vibrational modes with 30 nm spatial resolution for dielectric layers with different thicknesses.
TL;DR: In this article, photoswitching ensembles of optically bistable organic molecular markers from a non-fluorescent to a fluorescent state and back was demonstrated by an isomerization reaction of a photochromic compound serving as a reversible energy acceptor of a fluorescent compound.
Abstract: We demonstrate the breaking of the diffraction resolution barrier in far-field fluorescence microscopy by photoswitching ensembles of optically bistable organic molecular markers from a non-fluorescent to a fluorescent state and back. The photoswitching is accomplished by an isomerization reaction of a photochromic compound serving as a reversible energy acceptor of a fluorescent compound. The surpassing of the diffraction barrier with power levels of only a few hundred W cm−2 of continuous wave irradiation is evidenced both in the effective point spread function and in the fluorescence images of test samples.
TL;DR: The SESAM, a high-resolution 200-kV FEG-TEM equipped with a monochromator and an in-column MANDOLINE filter, is reported on, demonstrating its performance and new opportunities to do unique experiments that may advance the frontiers of microscopy.
Abstract: We report on the sub-electron-volt-sub-angstrom microscope (SESAM), a high-resolution 200-kV FEG-TEM equipped with a monochromator and an in-column MANDOLINE filter. We report on recent results obtained with this instrument, demonstrating its performance (e.g., 87-meV energy resolution at 10-s exposure time, or a transmissivity of the energy filter of T1 ev = 11,000 nm2). New opportunities to do unique experiments that may advance the frontiers of microscopy in areas such as energy-filtered TEM, spectroscopy, energy-filtered electron diffraction and spectroscopic profiling are also discussed.
TL;DR: X-ray crystallographic measurements in conjunction with solution X-ray diffraction and NMR methods have been used to determine the structure of gold(I) rings, and insight into the dynamics are gained.
Abstract: We report the synthesis and solution- and solid-state characterization of gold(I) rings with short 1,9-transannular Au···Au interactions. The 9- and 16-membered gold(I) rings were prepared by react...
01 Jan 2006
TL;DR: In optical microscopy, the lateral spatial resolution is determined by the wavelength of the light used and the numerical aperture (NA) of the objective lens as mentioned in this paper, which is the most important limitation inherent in lateral spatial resolutions.
Abstract: The biggest limitation inherent in optical microscopy is its lateral spatial resolution, which is determined by the wavelength of the light used and the numerical aperture (NA) of the objective lens. Another important limitation is the resolution in the direction of the optical axis, conventionally called z, which is related to the depth of field. The presence of a finite aperture gives rise to undesirable and rather complicated characteristics in the image. In essence, the depth of field depends on the size of structure or spatial frequency being imaged.
TL;DR: In this paper, a series of simulations with realistic values for residual aberrations predict nanometer-scale depth resolution for Bi dopant atoms in Si (110) for an instrument corrected up to fifth order.
Abstract: The implementation of aberration correction for the scanning transmission electron microscope (STEM) enables the use of larger probe-forming apertures, improving the transverse resolution significantly and also bringing depth resolution at the nanometer scale. This opens up the possibility of three-dimensional imaging by optical sectioning, and nanometer-scale depth resolution has been demonstrated for amorphous and off-axis samples. For crystalline materials it is usual to image in a zone axis orientation to achieve atomic resolution. In this case, the tendency for the beam to channel along the columns complicates the simple optical sectioning technique. Here we conduct a series of simulations which demonstrate that higher beam convergence angles available in next generation aberration correctors can overcome this limitation. Detailed simulations with realistic values for residual aberrations predict nanometer-scale depth resolution for Bi dopant atoms in Si (110) for an instrument corrected up to fifth order. Use of a monochromator appears to significantly improve the depth resolution.
TL;DR: A density functional study of the geometry optimized adsorption of four L-Cys forms-the molecule, the anion, the neutral radical, and its zwitterion adsorbed a-top-at the bridge and at the threefold hollow site of a planar Au(111) Au12 cluster.
Abstract: The amino acid L-cysteine (Cys) adsorbs in highly ordered (3√3 × 6) R30° lattices on Au(111) electrodes from 50 mM ammonium acetate, pH 4.6. We provide new high-resolution in situ scanning tunneling microscopy (STM) data for the L-Cys adlayer. The data substantiate previous data with higher resolution, now at the submolecular level, where each L-Cys molecule shows a bilobed feature. The high image resolution has warranted a quantum chemical computational effort. The present work offers a density functional study of the geometry optimized adsorption of four L-Cys formsthe molecule, the anion, the neutral radical, and its zwitterion adsorbed a-topat the bridge and at the threefold hollow site of a planar Au(111) Au12 cluster. This model is crude but enables the inclusion of other effects, particularly the tungsten tip represented as a single or small cluster of W-atoms, and the solvation of the L-Cys surface cluster. The computational data are recast as constant current−height profiles as the most common in...
TL;DR: The development of compact transmission soft x-ray microscopy (XM) with sub-50 nm spatial resolution for biomedical applications is described and a gold mesh image was obtained with 45 nm resolution at x580 magnification and 1 min exposure.
Abstract: In this paper, the development of compact transmission soft x-ray microscopy (XM) with sub-50 nm spatial resolution for biomedical applications is described. The compact transmission soft x-ray microscope operates at lambda = 2.88 nm (430 eV) and is based on a tabletop regenerative x-ray source in combination with a tandem ellipsoidal condenser mirror for sample illumination, an objective micro zone plate and a thinned back-illuminated charge coupled device to record an x-ray image. The new, compact x-ray microscope system requires the fabrication of proper x-ray optical devices in order to obtain high-quality images. For an application-oriented microscope, the alignment procedure is fully automated via computer control through a graphic user interface. In imaging studies using our compact XM system, a gold mesh image was obtained with 45 nm resolution at x580 magnification and 1 min exposure. Images of a biological sample (Coscinodiscus oculoides) were recorded.