Sub-diffraction resolution

Figure Bl.22.11. Near-field scanning optical microscopy fluorescence image of oxazine molecules dispersed on a PMMA film surface. Each protuberance in this three-dimensional plot corresponds to the detection of a single molecule, the different intensities of those features being due to different orientations of the molecules. Sub-diffraction resolution, in this case on the order of a fraction of a micron, can be achieved by the near-field scaiming arrangement. Spectroscopic characterization of each molecule is also possible. (Reprinted with pennission from [82]. Copyright 1996 American Chemical Society.)...

The enhanced near-field of plasmon resonant metal nanoparticles has also been employed to induce local photolithography [27]. Due to the strongly confined nature of the near-field, sub-diffraction resolution is achievable. Plasmon enhanced nanolithography will be discussed in a later section. There have also been proposals on plasmon field-enhanced photochemistry and photocatalysis. 

Further developments are also expected in imaging applications with faster imaging methods with higher spatial resolution becoming available (e.g. sub-diffraction-limited spatial resolution). Advanced non-linear techniques such as CARS and specialist methods such as ROA will broaden their respective application areas, as instruments become more compact and more systems become commercially available. 

A limiting factor in electron microscopy is the quality of the electron beam. Aberrations introduced by the optics limit both spatial resolution and analytical capabilities. There is a need to correct for the spherical and chromatic aberrations introduced by the electron optics. This will result in improved coherence of the beam and improved imaging and diffraction. In particular, these advances will permit the analysis of amorphous samples. Smaller beam sizes can also be achieved, allowing for sub-Angstrom resolution chemical analysis of samples. Development of higher-quality electron beams and short pulses of electron beams would broaden and deepen the application of electron microscopy. 

M.J. Rust, M. Bates, X. Zhuang, Sub-diffraction-limit imaging by stochastic optical reconstruction microscopy (STORM). Nat. Meth. 3, 793-796 (2006) S.T. Hess, T.P.K. Girirajan, M.D. Mason, Ultra-high resolution imaging by fluorescence photoactivation localization microscopy. Biophys. J. 91(11), 4258-4272 (2006)... 

To demonstrate that STORM can indeed resolve nearby fluorescent molecules with sub-diffraction-limit resolution, we first engineered samples with known relative positions of the fluorescent labels - double-stranded DNA labeled with two Cy3-Cy5 pairs separated by a well-defined number (135) of base pairs, corresponding to an inter-CyS distance of 46 nm along the contour of DNA [4]. The DNA strands were immobilized in a flat configuration to a quartz slide through multiple biotin-streptavidin linkages. The two Cy5 dyes were turned on and off, repetitively, and the image sequence was analyzed to determine the positions of individual activated Cy5 dye. We then constructed... 

Be able to exhibit sub-micron resolution (resolution being affected more by backscattering of electrons than by diffraction effects since the de Broglie wavelength of electron beams is of the order of a few tenths of an Angstrom),... 

Superresolution microscopy methods have revolutionized optical microscopy within approx, the last two decades [79]. These methods can be separated in localization-based methods [80], which exploit the possibihty to localize the isolated emission patterns of single molecules with high accuracy, and in methods which restrict the volume of excitation by stimulated emission. The latter can be combined with FCS resulting in STED-FCS (stimulated-emission-depletion FCS) [81, 82], where the excitation volume is minimized by an intensive donut-shaped STED laser pulse which depopulates basically all excited states except for a central volume of sub-diffraction size. This way, the spatial resolution Ad in lateral direction can be reduced to... 

Huang WJ, Zuo JM, Jiang B, Kwon KW, Shim M (2009) Sub-Mgstrom-resolution diffractive imaging of single nanocrystals. Nat Phys 5 129-133. doi 10.1038/nphysll61... 

Two-photon polymerization offers a unique combination of advantages. First, no topological constraints are present in the fabrication of a 3D microstructure. Second, sub-diffraction-limited resolution can be attained by employing laser intensities just... 

Fig. 18 Light intensity analysis for understanding the achievement of sub-diffraction-limit spatial resolution. Focal plane light intensity (dashed line) and the square of light intensity (solid line) distribution are associated with single-photon and two-photon excitation, respectively. Their derivative distribution is also shown. The inset is the diffraction pattern at the focal plane...

Fig. 20 Achievement of sub-diffraction-limit voxels, a SEM image of voxels formed under different exposure durations, and b an exposure time-dependent lateral spatial resolution. The right-lower inset represents the dependence in half-logarithm coordinates. For different curves, the laser pulse energies are 163 pj (filled squares), 137 pj (filled circles), 111 pJ (filled triangles) and 70 pJ (up-side-down filled triangles), respectively...

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