Focus-size

They employed a FIB of 30 keV Ga ions which as focused to a spot with a diameter which could be varied between 0.05 and 1 pm. The beam current varied with focus size between 13 pA and 1.2 nA, and sputter rate typically increased with beam current from 0.005 to 0.5pm3s 1. The beam control was automated, so that the major part of the specimen preparation was performed automatically, only the final high-resolution operations being carried out by manual adjustment of the milling area. Their preparation scheme was as follows ... 

Project focus Size of a project Number of team members Number of tasks in a project Required functionality... 

Laser focus size at target 5x1.2 to 9x2.5 mm2 depending on lens position... 

In the case of a bull s eye structure, the relative electromagnetic enhancement is about 100 (computed for an incoming plane wave and consistent with experiment (72)), but the structure radius and thus the laser beam focus spot are about 4 times the diffraction limit (minimum focus size). If we compare the relative intensity enhancement to the case of a diffraction-limited spot, the intensity with the bull s eye is increased by 100x(l/4) = 6.25, which is about the enhancement with a single (bare) aperture with a tightly focused beam. Of course, this argument has to be supplemented with the influence the emission rate and the directivity of the fluorescence beam, which contribute to the overall enhanced fluorescence. However,... 

Focus size HxV mm2 (2.3 a) Quoted X range (A or eV) Usual operational A or bill Intensity (photons s 1 mm-2) Detector/Ref/ Notes... 

Laser capture microdissection was combined with MALDl-MS by several groups [49-52], In one study, the MALDl analysis of microdissected cells from human breast cancer in comparison to normal breast epithelial cells was reported [49], with more than 40 peaks in the MALDl mass spectra being found to differ in intensity between the cancer and normal tissues. This approach represents another way of achieving laterally resolved analytical information. In this case, it was not the focus size of the desorbing laser beam in the mass spectrometer. 

At constant focus size, it was shown that FCS cannot distinguish between diffusion constrained by elastic force, walking confined diffusion, and hop diffusion averaged over many measurements [44]. The simulations indicate that the mean square displacements of all these types of restricted diffusion can refiably be interpreted using one archetypal model presented by the following equation ... 

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