共查询到20条相似文献，搜索用时 50 毫秒
1.
M Howells C Jacobsen J Kirz R Feder K McQuaid S Rothman 《Science (New York, N.Y.)》1987,238(4826):514-517
X-ray holography offers the possibility of three-dimensional microscopy with resolution higher than that of the light microscope and with contrast based on x-ray edges. In principle, the method is especially advantageous for biological samples if x-rays in the wavelength region between the carbon and oxygen K edges are used. However, until now the achieved resolution has not exceeded that of the light microscope because of the poor coherence properties of the x-ray sources and the low resolution of the detectors that were available. With a recently developed x-ray source based on an undulator on an electron storage ring, and high resolution x-ray resist, a hologram has been recorded at about 400-angstrom resolution. The experiment utilized x-rays with wavelengths of 24.7 angstroms and required a 1-hour exposure of the pancreatic zymogen granules under study. 相似文献
2.
Guest JR Stievater TH Chen G Tabak EA Orr BG Steel DG Gammon D Katzer DS 《Science (New York, N.Y.)》2001,293(5538):2224-2227
We combined coherent nonlinear optical spectroscopy with nano-electron volt energy resolution and low-temperature near-field microscopy with subwavelength resolution (相似文献
3.
A method has been developed for performing fast time-resolved experiments with a scanning tunneling microscope. The method uses the intrinsic nonlinearity in the microscope's current versus voltage characteristics to resolve optically generated transient signals on picosecond time scales. The ability to combine the spatial resolution of tunneling microscopy with the time resolution of ultrafast optics yields a powerful tool for the investigation of dynamic phenomena on the atomic scale. 相似文献
4.
Aeschlimann M Brixner T Fischer A Kramer C Melchior P Pfeiffer W Schneider C Strüber C Tuchscherer P Voronine DV 《Science (New York, N.Y.)》2011,333(6050):1723-1726
We introduce a spectroscopic method that determines nonlinear quantum mechanical response functions beyond the optical diffraction limit and allows direct imaging of nanoscale coherence. In established coherent two-dimensional (2D) spectroscopy, four-wave-mixing responses are measured using three ingoing waves and one outgoing wave; thus, the method is diffraction-limited in spatial resolution. In coherent 2D nanoscopy, we use four ingoing waves and detect the final state via photoemission electron microscopy, which has 50-nanometer spatial resolution. We recorded local nanospectra from a corrugated silver surface and observed subwavelength 2D line shape variations. Plasmonic phase coherence of localized excitations persisted for about 100 femtoseconds and exhibited coherent beats. The observations are best explained by a model in which coupled oscillators lead to Fano-like resonances in the hybridized dark- and bright-mode response. 相似文献
5.
A nondestructive imaging method, scanning near-field ultrasound holography (SNFUH), has been developed that provides depth information as well as spatial resolution at the 10- to 100-nanometer scale. In SNFUH, the phase and amplitude of the scattered specimen ultrasound wave, reflected in perturbation to the surface acoustic standing wave, are mapped with a scanning probe microscopy platform to provide nanoscale-resolution images of the internal substructure of diverse materials. We have used SNFUH to image buried nanostructures, to perform subsurface metrology in microelectronic structures, and to image malaria parasites in red blood cells. 相似文献
6.
Betzig E Trautman JK Harris TD Weiner JS Kostelak RL 《Science (New York, N.Y.)》1991,251(5000):1468-1470
In near-field scanning optical microscopy, a light source or detector with dimensions less than the wavelength (lambda) is placed in close proximity (lambda/50) to a sample to generate images with resolution better than the diffraction limit. A near-field probe has been developed that yields a resolution of approximately 12 nm ( approximately lambda/43) and signals approximately 10(4)- to 10(6)-fold larger than those reported previously. In addition, image contrast is demonstrated to be highly polarization dependent. With these probes, near-field microscopy appears poised to fulfill its promise by combining the power of optical characterization methods with nanometric spatial resolution. 相似文献
7.
Taubner T Korobkin D Urzhumov Y Shvets G Hillenbrand R 《Science (New York, N.Y.)》2006,313(5793):1595
The wave nature of light limits the spatial resolution in classical microscopy to about half of the illumination wavelength. Recently, a new approach capable of achieving subwavelength spatial resolution, called superlensing, was invented, challenging the already established method of scanning near-field optical microscopy (SNOM). We combine the advantages of both techniques and demonstrate a novel imaging system where the objects no longer need to be in close proximity to a near-field probe, allowing for optical near-field microscopy of subsurface objects at sub-wavelength-scale lateral resolution. 相似文献
8.
R Cauble Da Silva LB TW Barbee P Celliers C Decker RA London JC Moreno JE Trebes AS Wan F Weber 《Science (New York, N.Y.)》1996,273(5278):1093-1096
X-ray lasers (XRLs) have experimental average gains that are significantly less than calculated values and a persistently low level of spatial coherence. An XRL has been used both as an injected signal to a short XRL amplifier and as an interferometer beam to measure two-dimensional local gain and density profiles of the XRL plasma with a resolution near 1 micrometer. The measured local gain is in agreement with atomic models but is unexpectedly spatially inhomogeneous. This inhomogeneity is responsible for the low level of spatial coherence observed and helps explain the disparity between observed and simulated gains. 相似文献
9.
Suenaga K Tence M Mory C Colliex C Kato H Okazaki T Shinohara H Hirahara K Bandow S Iijima S 《Science (New York, N.Y.)》2000,290(5500):2280-2282
Electron energy-loss spectroscopy (EELS) is widely used to identify elemental compositions of materials studied by microscopy. We demonstrate that the sensitivity and spatial resolution of EELS can be extended to the single-atom limit. A chemical map for gadolinium (Gd) clearly reveals the distribution of Gd atoms inside a single chain of metallofullerene molecules (Gd@C82) generated within a single-wall carbon nanotube. This characterization technique thus provides the "eyes" to see and identify individual atoms in nanostructures. It is likely to find broad application in nanoscale science and technology research. 相似文献
10.
Liu HH Schmidt S Poulsen HF Godfrey A Liu ZQ Sharon JA Huang X 《Science (New York, N.Y.)》2011,332(6031):833-834
Over the past decade, efforts have been made to develop nondestructive techniques for three-dimensional (3D) grain-orientation mapping in crystalline materials. 3D x-ray diffraction microscopy and differential-aperture x-ray microscopy can now be used to generate 3D orientation maps with a spatial resolution of 200 nanometers (nm). We describe here a nondestructive technique that enables 3D orientation mapping in the transmission electron microscope of mono- and multiphase nanocrystalline materials with a spatial resolution reaching 1 nm. We demonstrate the technique by an experimental study of a nanocrystalline aluminum sample and use simulations to validate the principles involved. 相似文献
11.
A comparison of the sensitivity of canopy scale estimators of leaf chlorophyll, obtainable with Sentinel-2 spectral resolution, to soil, canopy and leaf mesophyll factors, was addressed. The analysis of a synthetic dataset, generated simulating the reflectance in the 1–4 LAI range of canopies for the main general classes of leaf inclination (i.e. erectophile, plagiophile, spherical, planophile and extremophile) and for different soil types was used for such a purpose. The synthetic dataset was obtained using the PROSPECT5-4SAIL model in the direct mode with a large variety of soil backgrounds. Additionally an experimental dataset including airborne hyperspectral data gathered during ESA (European Space Agency) campaigns SPARC and AGRISAR, was employed to simulate Sentinel-2 spectral and spatial resolution, to confirm model results. Analysis of the synthetic and experimental datasets indicated that: (i) the CVI (Chlorophyll Vegetation Index), relying only on visible and NIR (Near Infra-Red) bands and obtainable at 10 m spatial resolution, can be used as leaf chlorophyll estimator, at growth stages suitable for nitrogen fertilizer topdressings, for all canopy structures except for erectophile canopies; (ii) better results can be obtained by using different indices for different leaf architectures, with TCI/OSAVI (Triangular Chlorophyll Index/Optimized Soil Adjusted Vegetation Index) performing better for erectophile canopies, whereas MTCI (MERIS Terrestrial Chlorophyll Index) provides better results for planophile canopies, despite the fact that these indices require bands obtainable at 20 m spatial resolution from Sentinel-2 data. 相似文献
12.
选取影响朱鹮生境适宜性的9个环境因子,基于层次分析法（AHP）构建生境适宜指数（HSI）模型,结合地理探测器,分析陕西省洋县朱鹮生境适宜性程度及主要影响因子。结果表明:1）洋县朱鹮生境适宜性整体处于中等偏高水平;2）洋县境内朱鹮生境适宜区和较适宜区空间分布连贯性较差,空间分异特征明显,呈现东、南、北高,中间和西低的格局;3）单因子中,对朱鹮生境适宜性空间分异特征解释力较强的主要因子由大到小依次为距水体距离（0.501）、距水源距离（0.359）、植被类型（0.162）、海拔（0.155）、距道路距离（0.152）,其他环境因子的解释力（q）偏弱,q均未超过0.1;4）交互因子中,q（x1∩x2）为0.5以上交互作用的因子均是距水源（水体）距离叠加其他因子产生。其中,q（距水体距离∩距道路距离）为0.602,仅次于q（距水体距离∩距水源距离）最高值（0.725）。研究可为濒危动物生境保护以及栖息地管理提供理论基础和科学依据。 相似文献
13.
The combination of specific probes and advanced optical microscopy now allows quantitative probing of biochemical reactions in living cells. On selected systems, one can detect and track a particular protein with single-molecule sensitivity, nanometer spatial precision, and millisecond time resolution. Metabolites, usually difficult to detect, can be imaged and monitored in living cells with coherent anti-Stokes Raman scattering microscopy. Here, we describe the application of these techniques in studying gene expression, active transport, and lipid metabolism. 相似文献
14.
High resolution satellite imagery has the potential to map within-field variation in crop growth and yield. This study examined
SPOT 5 satellite multispectral imagery for estimating grain sorghum yield. A 60 km × 60 km SPOT 5 scene and yield monitor
data from three grain sorghum fields were recorded in south Texas. The satellite scene contained four spectral bands (green,
red, near-infrared and mid-infrared) with a 10-m spatial resolution. Subsets were extracted from the scene that covered the
three fields. Images with pixel sizes of 20 and 30 m were also generated from the individual field images to simulate coarser
resolution satellite imagery. Vegetation indices and principal components were derived from the images at the three spatial
resolutions. Grain yield was related to the vegetation indices, the four bands and the principal components for each field,
and for all the fields combined. The effect of the mid-infrared band on estimates of yield was examined by comparing the regression
results from all four bands with those from the other three bands. Statistical analysis showed that the 10-m, four-band image
and the aggregated 20-m and 30-m images explained 68, 76 and 83%, respectively, of the variation in yield for all the fields
combined. The coefficient of determination between yield and the imagery increased with pixel size because of the smoothing
effect. The inclusion of the mid-infrared band slightly improved the R
2 values. These results indicate that high resolution SPOT 5 multispectral imagery can be a useful data source for determining
within-field yield variation for crop management. 相似文献
15.
Nellist PD Chisholm MF Dellby N Krivanek OL Murfitt MF Szilagyi ZS Lupini AR Borisevich A Sides WH Pennycook SJ 《Science (New York, N.Y.)》2004,305(5691):1741
Despite the use of electrons with wavelengths of just a few picometers, spatial resolution in a transmission electron microscope (TEM) has been limited by spherical aberration to typically around 0.15 nanometer. Individual atomic columns in a crystalline lattice can therefore only be imaged for a few low-order orientations, limiting the range of defects that can be imaged at atomic resolution. The recent development of spherical aberration correctors for transmission electron microscopy allows this limit to be overcome. We present direct images from an aberration-corrected scanning TEM that resolve a lattice in which the atomic columns are separated by less than 0.1 nanometer. 相似文献
16.
目前,基于国内外发射的各种卫星传感器观测数据的陆地气溶胶光学厚度（AOD）反演方法与应用研究已相对成熟。然而,针对我国国产高空间分辨率（如高分一号）卫星数据的城市小区域尺度的反演与应用则相对较少。因此,选择使用深蓝算法对我国重要的工业型城市——徐州市进行国产GF-1 WFV数据AOD反演与空间特征分析,并利用地基AERONET同期数据进行反演结果验证。研究结果显示,2015—2017年6期的徐州市AOD整体空间格局稳定,均以人口聚集的城区呈高值分布为特征,不随季节变化,说明该地区空气污染源极可能以城市人为排放为主;与AERONET站点同期数据的相关性分析与时序分析结果表明,基于GF-1 WFV高空间分辨率卫星数据的徐州市AOD反演结果质量良好。建议今后在大数据支撑下,应充分利用时空数据融合及机器学习等先进技术手段,弥补受云覆盖影响下单时间窗口GF-1卫星数据AOD反演的缺陷,以期达到国产高分卫星的更高时间、更高空间分辨率以及实时监测与预测的更高业务目标。 相似文献
17.
Hodgman SS Dall RG Manning AG Baldwin KG Truscott AG 《Science (New York, N.Y.)》2011,331(6020):1046-1049
A major advance in understanding the behavior of light was to describe the coherence of a light source by using correlation functions that define the spatio-temporal relationship between pairs and larger groups of photons. Correlations are also a fundamental property of matter. We performed simultaneous measurement of the second- and third-order correlation functions for atoms. Atom bunching in the arrival time for pairs and triplets of thermal atoms just above the Bose-Einstein condensation (BEC) temperature was observed. At lower temperatures, we demonstrated conclusively the long-range coherence of the BEC for correlation functions to third order, which supports the prediction that like coherent light, a BEC possesses long-range coherence to all orders. 相似文献
18.
Three-dimensional readout of flash x-ray images of living sperm in water by atomic-force microscopy 总被引：4，自引：0，他引：4
T Tomie H Shimizu T Majima M Yamada T Kanayama H Kondo M Yano M Ono 《Science (New York, N.Y.)》1991,252(5006):691-693
The imaging of living specimens in water by x-ray microscopy can be greatly enhanced with the use of an intense flash x-ray source and sophisticated technologies for reading x-ray images. A subnanosecond [corrected] x-ray pulse from a laser-produced plasma was used to record the x-ray image of living sea urchin sperm in an x-ray resist. The resist relief was visualized at high resolution by atomic-force microscopy. Internal structure of the sperm head was evident, and the carbon density in a flagellum was estimated from the relief height. 相似文献
19.
Individual carbocyanine dye molecules in a sub-monolayer spread have been imaged with near-field scanning optical microscopy. Molecules can be repeatedly detected and spatially localized (to approximately lambda/50 where lambda is the wavelength of light) with a sensitivity of at least 0.005 molecules/(Hz)(1/2) and the orientation of each molecular dipole can be determined. This information is exploited to map the electric field distribution in the near-field aperture with molecular spatial resolution. 相似文献
20.
遥感影像分辨率的高低直接影响着森林植被监测的精度、成本和效率,故选择适合森林植被监测的影像最佳分辨率具有重要的应用价值。针对森林植被监测影像最佳分辨率选择方法及结果缺乏的问题,从林业实际应用出发,提出了基于1个步长的变异函数分析空间变异并综合考虑监测精度、成本和效率来确定森林植被监测影像最佳分辨率方法。基于最新的国产高分二号（GF-2）全色影像,利用1个步长的变异函数对湖南常宁洋泉镇林区3种典型分布类型森林植被进行拟合分析,初步确定适合森林植被监测的影像最低分辨率。然后对重采样形成的不同尺度多光谱影像分别进行监督分类,并对结果进行定量定性分析,结合影像成本和数据处理时间,找到适合不同类型森林植被监测的影像最佳分辨率。研究表明:不同分布类型的森林植被,适合遥感监测的影像最佳分辨率不同:①小冠幅森林植被3.2 m;②大冠幅森林植被16.0 m;③混合冠幅森林植被8.0 m。该森林植被遥感监测影像最佳分辨率确定方法和结果可为其他区域森林植被遥感监测影像最佳分辨率确定提供借鉴。 相似文献