Micro spatial resolution

Since the mass-transfer coefficient at a micropipette is inversely proportional to its radius, the smaller the pipette the faster heterogeneous rate constants can be measured. Micrometer-sized pipettes are too large to probe rapid CT reactions at the ITIES. Such measurements require smaller (nm-sized) pipettes. Nanopipettes are also potentially useful as SECM tips (see Section IV.D) because they can greatly improve spatial resolution of that technique. The fabrication of nanopipettes was made possible by the use of a micro-processor-controlled laser pipette puller capable of puling quartz capillaries [26]. Using this technique, Wei et al. produced nanopipettes as small as 20 nm tip radius and employed them in amperometric experiments [9]. 

Micro-coils can be used to reach higher spatial resolutions, as a result of the increase in sensitivity of very small rf coils. The possible resolution in NMR... 

The laser source is a Nd YAG pulsed laser, operating at 1064 nm, which delivers about 10 mJ on the sample surface, in 8 ns. The spatial lateral resolution of the LIBS measurements corresponds to the dimensions of the micro-crater left by the laser on the sample surface. The same dimensions are also a measurement of the damage induced on the pigment. A computer-enhanced enlargement of a typical laser crater is shown in Figure 2 its diameter does not exceed 10 pm, which is practically invisible at naked eye. The reduced size of the crater also allows for a high spatial resolution of the LIBS analysis. 

Although not yet routine, the use of pXRF analysers both for rock outcrop and core elemental determinations is already showing much promise. Their analysis window is approximately 1 cm in diameter, such that pXRF instruments offer a compromise between the spatial resolution offered by micro-analytical techniques such as LA-ICP-MS, and the... 

The optical setup for time-resolved micro-luminescence measurements is based around an Axiotech 100 HD Zeiss microscope, modified to allow laser injection and fluorescence collection. The sample is observed either under transmission or reflection of polarized white light, or under UV illumination (HBO lamp). A set-up consisting of a dichroic mirror, for the selection of the excitation wavelength, and an objective (Epiplan Neofiuar obj. > 350 nm Ealing/Coherent reflection obj. < 350 nm) is used to focus the laser beam on the sample (spatial resolution over 5 pm with a x50 objective). The lim-... 

With the help of a micro-Raman setup the laser spot can be focused down to about 1 pm in diameter. This allows for the differentiation of single bacterial cells or a biochemical analysis of subcellular components within bacterial (diameter approx. 1 pm) or yeast cells (diameter approx. 5-10pm). A confocal Raman setup achieves an even better spatial resolution [6, 7]. This possibility enables Raman mapping or imaging experiments with spatially resolved information of the whole sample in axial and lateral directions. 

E.H. Lehmann, G. Frei, G. Kuhne, P. Boillat, The micro-setup for neutron imaging A major step forward to improve the spatial resolution. Nucl. Instrum. Methods, Sect. A 576, 389 (2007)... 

Raman spectroscopy Raman spectra from small SWNT pieces with typical dimensions of 100 pm were recorded in the back-scattering geometry using two different micro-Raman setups comprised of a triple monochromator DILOR XY and a CCD detector system, cooled either to liquid nitrogen temperature or -100°C. The 488 or 514.5 nm line of an Ar+ laser, as well as the 647.1 nm line of a Kr+ laser, were used for excitation, while the beam intensity on the sample was =0.5 mW. The laser line was focused on the sample by means of a lOOx objective with a spatial resolution of 1 pm. 

Several variations of Raman spectroscopy have been developed with the purpose of enhancing the sensitivity [surface-enhanced Raman spectroscopy (SERS)], improving the spatial resolution (micro-Raman spectroscopy), or acquiring very specific information (resonance Raman spectroscopy) (Laserna, 1996). Specifically, SERS (Fleischmann et al., 1974) is normally done in a silver or gold colloid or a... 

Computational fluid dynamics enables us to investigate the time-dependent behavior of what happens inside a reactor with spatial resolution from the micro to the reactor scale. That is to say, CFD in itself allows a multi-scale description of chemical reactors. To this end, for single-phase flow, the space resolution of the CFD model should go down to the scales of the smallest dissipative eddies (Kolmogorov scales) (Pope, 2000), which is inversely proportional to Re-3/4 and of the orders of magnitude of microns to millimeters for typical reactors. On such scales, the Navier-Stokes (NS) equations can be expected to apply directly to predict the hydrodynamics of well-defined system, resolving all the meso-scale structures. That is the merit of the so-called DNS. 

Chan, K. L. A. and Kazarian, S. G. (2003) New opportunities in micro- and macro-attenuated total reflection infrared spectroscopic imaging spatial resolution and sampling versatility. Appl. Spectrosc. 57, 381. 

Raman microscopy was developed in the 1970s. Delhaye (34) in 1975 made the first micro Raman measurement. Simultaneously, Rosasco (35, 36) designed a Raman microprobe instrument at the National Bureau of Standards (now the NIST). This early work established the utility of Raman spectroscopy for microanalysis. The technique provides the capability of obtaining analytical-quality Raman spectra with 1 pm spatial resolution using samples in the picogram range. Commercial instruments are available. 

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