Atom lithography of iron

Atom lithography is a technique in which a light field is used to pattern an atomic beam. This patterned flux is then deposited onto a substrate, resulting in a nanostructured thin film. The smallest structures that have been made thus far using this technique are around 30 nm wide. This thesis investigates the technique, expanding its possibilities. The work-horse for the development of atom lithography has been Cr, as this transition metal atom has a closed transition in a wavelength range that is accessible to dye lasers. We extend the technique to Fe, the first ferromagnetic element to be used for atom lithography. The setup that was used to do this experiment is described, along with its critical design parameters. We present nanostructures that are typically 50 nm wide, and up to 4 nm high. The spacing between the nanolines is 186.05 nm. The nanostructure profile is compared to that of a simulated deposition process, and found to match. To the authors’ knowledge, this is the first demonstration of direct write atom lithography without laser cooling. A preliminary incursion into the magnetic properties of the nanostructures deposited is presented. In addition to giving an overview of the general ferromagnetic properties that might be expected, a deeper investigation of the magnetic anisotropy of the nanostructures deposited in this experiment is given. Novel resonant light masks are used in an experiment performed at the University of Konstanz (Germany). These light masks, using exactly instead of nearly resonant light, reveal some intriguing quantum mechanical effects. The most important of these features is the possibility to place structures closer together – at quarter wavelength spacings rather than half-wavelength intervals. Finally, the influence of surface diffusion on the structures obtained in an atom lithography experiment is investigated using kinetic Monte Carlo simulations. Several diffusion limiting effects are investigated; the influence of small amounts of residual reactive background gas is found to describe the experimental observations

Laser-cooling simulation based on the semiclassical approach

We investigate the region of validity of the semiclassical approach to simulating laser cooling. We conclude that for the commonly used pi(x) pi(y) polarization-gradient configuration, the semiclassical approach is valid only for transitions with recoil parameters epsilon(r), on the order of 10(-4) or less. For the standard laser-cooling transitions only the transitions in Rb and Cs satisfy this condition. For the Doppler and sigma(+)sigma(-) polarization-gradient configuration the semiclassical approach is valid for most of the commonly used transitions; however, the expected gain in execution speed compared with quantum Monte Carlo calculations has been realized only in part. A drastic reduction in calculation time is to be expected by implementing an analytical approach to the long-term contribution of the diffusion coefficient. (c) 2005 Optical Society of America

Atom lithography of Fe

Direct write atom lithography is a technique in which nearly resonant light is used to pattern an atom beam. Nanostructures are formed when the patterned beam falls onto a substrate. We have applied this lithography scheme to a ferromagnetic element, using a 372 nm laser light standing wave to pattern a beam of iron atoms. In this proof-of-principle experiment, we have deposited a grid of 50-nm-wide lines 186 nm apart. These ultraregular, large-scale, ferromagnetic wire arrays may generate exciting new developments in the fields of spintronics and nanomagnetics. (C) 2004 American Institute of Physics

Measurement of the total antioxidant response using a novel automated method in subjects with nonalcoholic steatohepatitis

BACKGROUND: Oxidative stress, an increase in oxidants and/or a decrease in antioxidant capacity, is one of the potential biochemical mechanisms involved in the pathogenesis of nonalcoholic steatohepatitis. We aimed to investigate the total antioxidant response using a novel automated method in nonalcoholic steatohepatitis subjects. As a reciprocal measure, we also aimed to determine total peroxide level in the same plasma samples. METHODS: Twenty-two subjects with biopsy proven nonalcoholic steatohepatitis and 22 healthy controls were enrolled. Total antioxidant response and total peroxide level measurements were done in all participants. The ratio percentage of total peroxide level to total antioxidant response was regarded as oxidative stress index. RESULTS: Total antioxidant response of subjects with nonalcoholic steatohepatitis was significantly lower than controls (p < 0.05), while mean total peroxide level and mean oxidative stress index were higher (all p < 0.05). In subjects with nonalcoholic steatohepatitis, fibrosis score was significantly correlated with total peroxide level, total antioxidant response and oxidative stress index (p < 0.05, r = 0.607; p < 0.05, r = -0.506; p < 0.05, r = 0.728, respectively). However, no correlation was observed between necroimflamatory grade and those oxidative status parameters (all p > 0.05). CONCLUSION: Nonalcoholic steatohepatitis is associated with increased oxidant capacity, especially in the presence of liver fibrosis. The novel automated assay is a reliable and easily applicable method for total plasma antioxidant response measurement in nonalcoholic steatohepatitis

Electrostatic clamp manufactured by novel method

Electrostatic clamps (ESCs), used in reticle and wafer handling, are presently manufactured using glass bonding and polishing technologies. We present a patented alternative concept to this process, relying on coating and etching processes rather than bonding. We manufactured a first prototype clamp based on a silicon-on-insulator wafer. The clamping operation was demonstrated, and the clamp’s performance was characterized. Clamping force, coating quality, and achieved morphology are characterized and understood

EBL2, a flexible, controlled EUV exposure and surface analysis facility

TNO is building EBL2 as a publicly accessible test facility for EUV lithography related development of photomasks, pellicles, optics, and other components. EBL2 will consist of a Beam Line, an XPS system, and sample handling infrastructure. EBL2 will accept a wide range of sample sizes, including EUV masks with or without pellicles. All types of samples will be loaded using a standard dual pod interface. EUV masks returned from EBL2 will retain their NXE compatibility. The Beam Line provides high intensity EUV irradiation from a Sn-fueled EUV source. EUV intensity, pupil, spectrum, and repetition rate are all adjustable. In-situ measurements by ellipsometry will enable real time monitoring of the sample condition. The XPS will be capable of analyzing the full surface area of EUV masks and pellicles, as well as performing angle resolved analysis on smaller samples. Sample transfer between the XPS and the Beam Line will be possible without breaking vacuum