Robert D. Frankel

Application And Analysis Of Production Suitability Of A Laser-Based Plasma X-Ray Stepper

A broadly applicable lithography tool figure of merit will be presented and evaluated for present technologies. A comparison of the cost effectiveness of current lithographic technologies shows that a laser generated, soft x-ray plasma proximity stepper is superior to competing technologies for production applications at one micrometer and below. The technology developments that make a soft x-ray proximity stepper more cost effective than other high resolution lithographic technologies will be discussed. Soft x-ray exposure sensitivity data will be presented for conventional novolak resists and acid catalyzed high sensitivity novolak-based materials. Resist profiles from soft x-ray exposures of standard, novolak-based resists will be compared to simulations obtained from a modified version of SAMPLE. In addition, x-ray and optical aerial image contrast calculations from SAMPLE will be compared. Novel aspects of the patented, high brightness Hampshire x-ray source will be presented and a comparison to other x-ray sources will be made. Lastly, the preliminary performance of a stepper employing Hampshires laser-based x-ray plasma source will be presented indicating the performance achieved to date.

Discussion of methods for depth enhancement in single and multiphoton-stimulated emission microscopy

Methods to enable enhanced tissue depth in stimulated emission imaging are discussed. To take advantage of the increased scattering length and reduced absorption in the near infrared, 2–4 photons are used for both molecular excitation and stimulated emission in stimulated fluorescence imaging. The method is called multiphoton-stimulated emission microscopy (MP-STEM). In a confocal microscope, the axial focal spot in 3-photon MP-STEM may be reduced to about ½ the wavelength of the stimulated emission beam, potentially enabling the detection of ballistic backscatter at the tissue surface. Also discussed is a microscope geometry that combines Bessel beam excitation with an orthogonal structured illumination stimulated emission beam. This geometry is called Bessel beam-stimulated emission microscopy (BB-STEM). It is shown that the axial focal spot diameter of the stimulated emission beam may be reduced to less than ½ of the stimulated emission beam wavelength for 1–3 photon stimulated emission processes, enabling dipole backscatter ballistic photons to be detected in both stimulated fluorescence and stimulated Raman processes. Dipole ballistic backscatter detection reduces emitter concentrations detection thresholds by the reduction of the detected stimulated emission beam background noise. Use of multiple time delays between the excitation and emission processes enables the use of these approaches to measure the fluorescent lifetime of species with multiple lifetimes. Also discussed are the challenges of these methods, including the required laser power, focal spot blooming, and array detectors.

[36] Application of nanosecond X-ray diffraction techniques to bacteriorhodopsin

Publisher Summary This chapter presents the application of nanosecond X-ray diffraction techniques to bacteriorhodopsin (BR). The magnitude of any conformational change that may take place during the BR photocycle is under debate. The resolution of this question can be answered by use the newly developed laser plasma X-ray source to obtain subnanosecond X-ray diffraction patterns throughout the course of the 20-msec photocycle. To generate the purple membrane diffraction pattern, the single-beam Nd+3glass development laser is used. Experiments are performed with highly chlorinated targets; room temperature Saran (C2H2C12) and pressed polycrystals of hexachloroethane (C2Cl6) held at 77 K and X-ray powder diffraction pattern from a purple membrane stack recorded on 2475 high-speed recording film. The information contained in these powder patterns can be used along with the phase information obtained from electron diffraction studies to yield a two-dimensional projection of the electron density of the purple membrane perpendicular to the plane of the membrane. This view offers a great deal of information about BR because its seven helices are arrayed roughly perpendicular to the membrane plane—for example, the projection looks down the helical chains.