Showing papers on "Resolution (electron density) published in 2003"
Journal Article•
TL;DR: In this paper, the authors proposed a new type of scanning fluorescence microscope capable of resolving 35 nm in the far field by employing stimulated emission to inhibit the fluorescence process in the outer regions of the excitation point spread function.
Abstract: We propose a new type of scanning fluorescence microscope capable of resolving 35 nm in the far field. We overcome the diffraction resolution limit by employing stimulated emission to inhibit the fluorescence process in the outer regions of the excitation point-spread function. In contrast to near-field scanning optical microscopy, this method can produce three-dimensional images of translucent specimens.
3,987 citations
TL;DR: A family of concepts has emerged that overcomes the diffraction barrier altogether and, relying on saturated optical transitions, these concepts are limited only by the attainable saturation level.
Abstract: For more than a century, the resolution of focusing light microscopy has been limited by diffraction to 180 nm in the focal plane and to 500 nm along the optic axis Recently, microscopes have been reported that provide three- to sevenfold improved axial resolution in live cells Moreover, a family of concepts has emerged that overcomes the diffraction barrier altogether Its first exponent, stimulated emission depletion microscopy, has so far displayed a resolution down to 28 nm Relying on saturated optical transitions, these concepts are limited only by the attainable saturation level As strong saturation should be feasible at low light intensities, nanoscale imaging with focused light may be closer than ever
983 citations
TL;DR: The calculated energy changes indicate that there may be significant contributions to inter-pigment energy interactions from molecular displacements and these may be of importance to photosynthetic energy transfer.
462 citations
TL;DR: This work shows that both high resolution and high contrast can be achieved by imaging from diffraction with a nanometer-sized coherent electron beam, and has the potential to image nonperiodic nanostructures, including biological macromolecules, at diffraction intensity–limited resolutions.
Abstract: Atomic imaging of three-dimensional structures has required a crystal in diffraction or a lens in electron imaging. Whereas diffraction achieves very high resolution by averaging over many cells, imaging gives localized structural information, such as the position of a single dopant atom. However, lens aberrations limit electron imaging resolution to about 1 angstrom. Resolution is reduced further by low contrast from weakscattering or from the limitations on electron dose for radiation-sensitive molecules. We show that both high resolution and high contrast can be achieved by imaging from diffraction with a nanometer-sized coherent electron beam. The phase problem is solved by oversampling and iterative phase retrieval. We apply this technique to image a double-wall carbon nanotube at 1-angstrom resolution, revealing the structure of two tubes of different helicities. Because the only requirement for imaging is a diffraction pattern sampled below the Nyquist frequency, our technique has the potential to image nonperiodic nanostructures, including biological macromolecules, at diffraction intensity-limited resolutions.
441 citations
01 Oct 2003-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: A 3D micro X-ray fluorescence (micro-XRF) analysis method based on a confocal Xray set-up is presented in this article, which is evaluated and illustrated with depth sensitive investigations of paint layers in ancient Indian Mughal miniatures.
Abstract: A new 3D micro X-ray fluorescence (micro-XRF) analysis method based on a confocal X-ray set-up is presented. The capabilities of this new method are evaluated and illustrated with depth sensitive investigations of paint layers in ancient Indian Mughal miniatures. Successive paint layers could be distinguished non-destructively with a depth resolution of about 10 μm. Major and minor elements are detectable and can be discriminated in different layers. New light could be shed on ancient painting techniques and materials with this new 3D micro-XRF set-up.
245 citations
TL;DR: The results are surprising in that they show that classification can be done with less than one photon per pixel in the limiting resolution shell, assuming Poisson-type photon noise in the image.
178 citations
TL;DR: Electron microscopy is at the highest-resolution limit of a spectrum of complementary morphological techniques and is the only technique with sufficient resolution to localize proteins to small membrane subdomains in the context of the cell.
Abstract: Electron microscopy (EM) is at the highest-resolution limit of a spectrum of complementary morphological techniques. When combined with molecular detection methods, EM is the only technique with sufficient resolution to localize proteins to small membrane subdomains in the context of the cell. Recent procedural and technical developments have increasingly improved the power of EM as a cell-biological tool.
166 citations
TL;DR: It is demonstrated not only that an antibody-tagged label is stable enough to be recorded in this microscopy mode, but also that subdiffraction resolution can be obtained using a standard immunofluorescence preparation.
Abstract: We report immunofluorescence imaging with a spatial resolution well beyond the diffraction limit. An axial resolution of approximately 50 nm, corresponding to 1/16 of the irradiation wavelength of 793 nm, is achieved by stimulated emission depletion through opposing lenses. We have demonstrated not only that an antibody-tagged label is stable enough to be recorded in this microscopy mode, but also that subdiffraction resolution can be obtained using a standard immunofluorescence preparation.
152 citations
TL;DR: A novel confocal microscope that uses separate low-numerical-aperture objectives with the illumination and collection axes crossed at angle theta from the midline to collect images in scattering media with high transverse and axial resolution, long working distance, large field of view, and reduced noise from scattered light is described.
Abstract: We describe a novel confocal microscope that uses separate low-numerical-aperture objectives with the illumination and collection axes crossed at angle θ from the midline. This architecture collects images in scattering media with high transverse and axial resolution, long working distance, large field of view, and reduced noise from scattered light. We measured transverse and axial (FWHM) resolution of 1.3 and 2.1 μm, respectively, in free space, and confirm subcellular resolution in excised esophageal mucosa. The optics may be scaled to millimeter dimensions and fiber coupled for collection of high-resolution images in vivo.
144 citations
TL;DR: New experiments made possible with a commercial transmission electron microscope equipped with a high-resolution electron energy loss spectrometer (EELS) are presented and the benefit of the increased resolution for detecting more details in near edge structures is shown.
142 citations
TL;DR: In this article, the authors compare experiments and simulations of a scanning tunneling microscope (STM) system and conclude that the combination of first-principle simulations with high-resolution measurements was decisive to arrive at consistent results.
TL;DR: In this article, the axial position of a fluorophore with sub-nanometer precision was determined by measuring the height of a fluorescein monolayer covering a 12nm step etched in silicon dioxide.
Abstract: We introduce a new fluorescence microscopy technique that maps the axial position of a fluorophore with subnanometer precision. The interference of the emission of fluorophores in proximity to a reflecting surface results in fringes in the fluorescence spectrum that provide a unique signature of the axial position of the fluorophore. The nanometer sensitivity is demonstrated by measuring the height of a fluorescein monolayer covering a 12-nm step etched in silicon dioxide. In addition, the separation between fluorophores attached to the top or the bottom layer in a lipid bilayer film is determined. We further discuss extension of this microscopy technique to provide resolution of multiple layers spaced as closely as 10 nm for sparse systems.
TL;DR: The charge density refinement of the protein was performed with the program mopro by using the transferability principle and the database of charge density parameters built from crystallographic analyses of peptides and amino acids, and the potentials obtained directly from the database are in excellent agreement with the experimental ones.
Abstract: The electron density and electrostatic potential in an Aldose Reductase holoenzyme complex have been studied by DFT and diffraction methods. Aldose reductase is involved in the reduction of glucose in the polyol pathway using NADPH as a co-factor. The ultra-high resolution of the diffraction data and the low thermal displacement parameters of the structure allow accurate atomic positions and an experimental charge density analysis. Based on the X-ray structural data, order-N Density Functional Theory (DFT) calculations have been performed on 711 atoms in the active site of the molecule. The charge density refinement of the protein was performed with program MoPro using the transferability principle and our database of charge density parameters built from crystallographic analyses of peptides and amino acids.
Journal Article•
TL;DR: In this article, the imaging performance in single-photon (l-p) and two-p (2p) fluorescence microscopy is compared in terms of the three-dimensional (3D) point spread function and the 3-D optical transfer function.
Abstract: Summary The imaging performance in single-photon (l-p) and two photon (2-p) fluorescence microscopy is described. Both confocal and conventional systems are compared in terms of.the three-dimensional (3-D) point spread function and the 3-D optical transfer function. Images of fluorescent sharp edges and layers are modelled •. giving resolution in transverse and axial directions. A comparison of the imaging properties is also given for a 4Pi confocal system. Confocal 2-p 4Pi fluorescence microscopy gives the best axial resolution in the sense that its 3-D optical transfer function has the strongest response along the axial direction.
TL;DR: This work shows a dramatic improvement of poorly diffracting DsbG crystals allowing high-resolution diffraction data measurement, and shows that dehydration is a simple, rapid, and inexpensive approach to convert poor quality crystals into diffraction quality crystals.
TL;DR: In this article, the authors demonstrate sub-diffraction lateral resolution of 28±2 nm in far-field fluorescence microscopy through stimulated emission depletion effected by an amplified laser diode.
Abstract: We demonstrate sub-diffraction lateral resolution of 28±2 nm in far-field fluorescence microscopy through stimulated emission depletion effected by an amplified laser diode. Measurement of the optical transfer function in the focal plane reveals a 6-fold enlargement of the spatial bandwith over the diffraction limit. The resolution is established by imaging individual fluorescent molecules on a surface. Corresponding to 1/25 of the responsible wavelength, the attained resolution represents a new benchmark in far-field microscopy and underscores the viability of fluorescence nanoscopy with visible light, conventional optics and compact laser systems .
TL;DR: In this article, the phase contrast in the x-ray images is about five times higher than the pure absorption contrast, which is a significant improvement over the pure absorbance contrast.
Abstract: We report on x-ray microscopy of advanced microelectronic devices imaged in Zernike-type phase contrast mode at 4 keV photon energy. Fresnel zone plates were used as high resolution x-ray objectives providing 60 nm spatial resolution. Integrated circuit copper interconnect structures were imaged in positive as well as negative phase contrast. In both cases the phase contrast in the x-ray images is about five times higher than the pure absorption contrast.
TL;DR: In this paper, the authors used far ultraviolet Spectroscopic Explorer (FUSE) data to investigate the molecular hydrogen (H2) content of intermediate velocity clouds (IVCs) in the lower halo of the Milky Way.
Abstract: Far Ultraviolet Spectroscopic Explorer (FUSE) data are used to investigate the molecular hydrogen (H2) content of intermediate-velocity clouds (IVCs) in the lower halo of the Milky Way. We analyze interstellar absorption toward 56 (mostly extragalactic) background sources to study H2 absorption in the Lyman and Werner bands in 61 IVC components at H I column densities ≥1019 cm-2. For data with good signal-to-noise ratio (S/N) (~9 per resolution element and higher), H2 in IVC gas is convincingly detected in 14 cases at column densities varying between ~1014 and ~1017 cm-2. We find an additional 17 possible H2 detections in IVCs in FUSE spectra with lower S/N. The molecular hydrogen fractions, f, vary between 10-6 and 10-3, implying a dense, mostly neutral gas phase that is probably related to the cold neutral medium (CNM) in these clouds. If the H2 stays in formation-dissociation equilibrium, the CNM in these clouds can be characterized by compact (D ~ 0.1 pc) filaments with volume densities on the order of nH ~ 30 cm-3. The relatively high detection rate of H2 in IVC gas implies that the CNM in these clouds is ubiquitous. More dense regions with much higher molecular fractions may exist, but it would be difficult to detect them in absorption because of their small size.
TL;DR: The scattering behaviour of A-scale electron probes in <001> and <110> silicon is examined using frozen phonon multislice calculations, with specific reference to the spatial resolution with which electron energy loss spectra can be related to local atomic structure.
TL;DR: The analysis of membrane proteins within this peculiar packing confirmed the high vertical resolution of the atomic force microscopy on biological samples, and led us to conclude that the image acquisition function was equally accurate for contouring protrusions with heights up to approximately 15 A.
TL;DR: In this paper, the correlation between the deformed martensite and the reverse transformed parent phase in the Ti-Ni shape memory alloy is directly demonstrated by in situ heating conventional transmission electron microscopy (CTEM) and high resolution electron microscope (HREM).
TL;DR: In this article, the three-dimensional microstructure of a Strombus decorus persicus seashell was studied by means of high-resolution electron microscopy and energy-variable X-ray diffraction on synchrotron beam lines.
Abstract: The three-dimensional microstructure of a Strombus decorus persicus seashell was studied by means of high-resolution electron microscopy and energy-variable X-ray diffraction on synchrotron beam lines. Energy variation in small steps allows the X-ray penetration depth to be changed precisely and, on this basis, for a non-destructive microstructural analysis with depth resolution to be developed. This technique enabled determination of depth-resolved microstructural parameters, such as the degree of the preferred orientation, the lamella size, and average microstrain fluctuations in both the prismatic and the crossed-lamellar layers of these seashells. The X-ray results were in good agreement with direct observations made by electron microscopy. A detailed study of the shell microstructure shed additional light on the relationship between the structural characteristics and superior mechanical properties of seashells.
TL;DR: In this article, a soft x-ray microscope based on Fresnel zone plate lenses and partially coherent illumination was used to achieve a spatial resolution of 20 nm at 207nm wavelength.
Abstract: A spatial resolution of 20 nm is demonstrated at 207-nm wavelength by use of a soft x-ray microscope based on Fresnel zone plate lenses and partially coherent illumination Nanostructural test patterns, formed by sputtered multilayer coatings and transmission electron microscopy thinning techniques, provide clear experimental results
TL;DR: It is shown, through theoretical prediction and initial experiments, that ESR microscopy, although much less developed, can improve upon the resolution limits of NMR, and successfully undertake the 1 mum resolution challenge.
TL;DR: In this paper, the root-mean-square distance (r.m.s.) between equivalent atoms is computed after optimal superposition of the two structures that are compared. But the dependence of the r.ms.s. values on the protein-pair dimensions is unknown.
Abstract: The most popular estimator of structural similarity is the root-mean-square distance (r.m.s.d.) between equivalent atoms, computed after optimal superposition of the two structures that are compared. It is known that r.m.s.d. values do not depend only on conformational differences but also on other features, for example the dimensions of the structures that are compared. An open question is how they might depend on the accuracy of the experimentally determined protein structures. Given that the accuracy of the protein crystal structures is generally estimated through the crystallographic resolution, it is important to know the dependence of the r.m.s.d. on the crystallographic resolution of the two structures that are compared. 14458 protein structure pairs of identical sequence were compared and the resulting r.m.s.d. values were normalized to 100-residue length to avoid the bias introduced by the dependence of the r.m.s.d. values on the protein-pair dimensions. On average, smaller r.m.s.d. values are associated with protein structure pairs at better resolution and the r.m.s.d. values tend to increase if the two proteins that are compared have been refined at different resolutions. For crystallographic resolutions ranging between 1.6 and 2.9 A, both relationships appear to be linear: r.m.s.d. = −0.73 + 0.48 resolution and delta_r.m.s.d. = 0.20 + 0.30 delta_resolution (`delta' indicating difference). Although the linearity of these relationships is not expected to hold outside the 1.6–2.9 A resolution range, they are useful in making the r.m.s.d. values more reliable.
TL;DR: Examples show that MACmode AFM is a favorable method in studying the topography of soft and weakly attached biological samples with high resolution under physiological conditions.
Proceedings Article•
09 Aug 2003TL;DR: A new particle filter that maintains samples in the state space at dynamically varying resolution for computational efficiency and requires significantly lower computation for performance comparable to a classical particle filter.
Abstract: Particle filters are used extensively for tracking the state of non-linear dynamic systems. This paper presents a new particle filter that maintains samples in the state space at dynamically varying resolution for computational efficiency. Resolution within siatespace varies by region, depending on the belief that the true state lies within each region. Where belief is strong, resolution is fine. Where belief is low, resolution is coarse, abstracting multiple similar states together. The resolution of the statespace is dynamically updated as the belief changes. The proposed algorithm makes an explicit bias-variance tradeoff to select between maintaining samples in a biased generalization of a region of state space versus in a high variance specialization at fine resolution. Samples are maintained at a coarser resolution when the bias introduced by the generalization to a coarse resolution is outweighed by the gain in terms of reduction in variance, and at a finer resolution when it is not. Maintaining samples in abstraction prevents potential hypotheses from being eliminated prematurely for lack of a sufficient number of particles. Empirical results show that our variable resolution particle filter requires significantly lower computation for performance comparable to a classical particle filter.
TL;DR: In this article, a sub-5-nm spatial resolution was achieved using full-diamond tips integrated in Si cantilevers, which is the state-of-the-art for this technique.
Abstract: Scanning spreading resistance microscopy is a two-dimensional carrier profiling technique now widely used for the characterization of silicon (Si) devices as well as other semiconductor materials. Whereas the state-of-the-art spatial resolution for this technique using commercial-diamond-coated silicon probes is limited to 10–20 nm, enhanced resolution is demonstrated through the use of full-diamond tips integrated in Si cantilevers. Sub-5-nm-spatial resolution is obtained on fully depleted silicon on isolator devices, putting the technique closer to the characterization requirements of the forthcoming semiconductor dimensions. Resistance and scanning electron microscope measurements clearly show that this enhanced resolution results from a smaller effective radius for full diamond tips as compared to the diamond-coated Si probes.
TL;DR: In this article, the results of European VLBI Network observations of 3 Broad Absorption Line quasars at 1.6 GHz were presented, and it was shown that the radio jet orientation in this source is probably near the line of sight.
Abstract: We present the results of European VLBI Network observations of 3 Broad Absorption Line quasars at 1.6 GHz. They are all compact with linear sizes less than 1 kpc. The flat spectral source, J1556 + 3517, is unresolved at about 20 mas resolution, indicating that the orientation of the radio jet in this source is probably near the line of sight. J1312 + 2319 shows asymmetric two-sided structure on a scale of several hundred pc. This structure resembles that of Compact Symmetric Objects (CSO), however it has a bright central component at the present resolution. The jet orientation of J1312 + 2319 may be far from the line of sight. J0957 + 2356 is also unresolved, but with a steep spectrum, therefore the jet orientation in this source is unclear. These results are not consistent with the unification of BAL and non-BAL quasars by orientation.
TL;DR: Electronics supplying the prism, drift tube, high-tension reference and critical lenses have been newly designed such that, in combination with the new electron optics, a sub-50 meV energy resolution has been realized, a 10-fold improvement over past post-column spectrometer designs.