The performance of a fluorescence detector in capillary electrophoresis (CE) using a light-emitting diode (LED) as excitation source is reported. An ultraviolet LED pulsed at a repetition rate of 500 Hz, combined with a time-discrimination and averaging acquisition system, was used. Limits of detection of 3 and 18 fmoles (at a signal-to-noise ratio equal to 3) were achieved for fluorescamine-derivatized bradykinin and lysine, respectively. This system exhibited a linear response for a concentration range between 54 and 417 microM for derivatized lysine, and between 1.81 and 23.58 microM for derivatized bradykinin. This detection system showed to be very convenient for routine analytical applications.

Extreme or rogue waves are large and unexpected waves appearing with higher probability than predicted by Gaussian statistics. Although their formation is explained by both linear and nonlinear wave propagation, nonlinearity has been considered a necessary ingredient to generate super rogue waves, i.e., an enhanced wave amplification, where the wave amplitudes exceed by far those of ordinary rogue waves. Here we show, experimentally and theoretically, that optical super rogue waves emerge in the simple case of linear light diffraction in one transverse dimension. The underlying physics is a long-range correlation on the random initial phases of the light waves. When subgroups of random phases appear recurrently along the spatial phase distribution, a more ordered phase structure greatly increases the probability of constructive interference to generate super rogue events (non-Gaussian statistics with superlong tails). Our results consist in a significant advance in the understanding of extreme waves formation by linear superposition of random waves, with applications in a large variety of wave systems.

Capillary electrophoresis (CE) and microchannel (MC) techniques are important tools in chemical and biological sciences, mainly in the study of genomes, transcriptomes, proteomes, metabolomes, and organic as well as inorganic ions. The speed of DNA sequencing increased significantly during the last decade with the use of capillary electrophoresis (CE). The time evolution of the bands' spatial profile inside capillaries and channels is of paramount importance, since the main goal of these techniques is to maximize resolution (the ratio between the spacing of the peaks and their mean standard deviations). In the present work, the propagator (retarded Green function) formalism is applied to solve a few problems which are typical for CE and MC. We also apply this mathematical method to the problem of velocity gradients along the capillary, i.e., the time evolution of the bands is analyzed when they enter regions where they migrate with different velocities.

AlSb, GaSb and InSb films were deposited by magnetron sputtering on Si and SiO2/Si substrates and their electronic and structural properties were investigated as a function of film thickness and deposition temperature. Elemental composition and thickness were investigated by Rutherford backscattering spectrometry and particle induced x-ray emission analysis, while x-ray diffraction provided information about phase and structure. Surface chemical composition was investigated by x-ray photoelectron spectroscopy. Here we demonstrate that polycrystalline AlSb films can be produced by magnetron sputtering, where films deposited at 550 °C attain a zincblende phase and exhibit the smallest amount of oxygen (compared to other deposition temperatures). GaSb grown by this technique at room temperature holds an amorphous structure, with excess Sb, but for films deposited at 400 °C the structure is polycrystalline, stoichiometric with a zincblende phase. InSb films with a thickness of 75 nm and thinner, deposited at room temperature, are amorphous and for increasing thickness the films attain a zincblende phase with polycrystalline structure. Sputtering performed at elevated temperatures yields films with improved crystalline quality.

InSb films with various thicknesses were deposited by magnetron sputtering on SiO2/Si substrates and subsequently irradiated with 17 MeV Au+7 ions. The structural and electronic changes induced by ion irradiation were investigated by synchrotron and laboratory based techniques. Ion irradiation of InSb transforms compact films (amorphous and polycrystalline) in open cell solid foams. The initial stages of porosity were investigated by transmission electron microscopy analysis and reveal the porous structure initiates as small spherical voids with approximately 3 nm in diameter. The evolution of porosity was investigated by scanning electron microscopy images, which show that film thickness increases up to 16 times with increasing irradiation fluence. Here we show that amorphous InSb films become polycrystalline foams upon irradiation with 17 MeV Au+7 ions at fluences above 1014 cm−2. The films attain a zincblende phase, with crystallites randomly oriented, similarly to the polycrystalline structure attained by thermal annealing of unirradiated films.