Maya Blue is a famous indigo-based pigment produced by the ancient Mayas. The organic/inorganic complexes inspired by Maya Blue have led to a new class of surface compounds that have novel applications to pigment industries. Materials analyzed in the present work are made by a synthetic route, and demonstrate chemical stability similar to that of the ancient Maya Blue samples. However, we have learned that stable complexes can be synthesized at much higher dye concentrations than used by the Mayas. Analysis by FT-Raman and FT-IR spectroscopy demonstrates the partial elimination of the selection rules for the centrosymmetric indigo, indicating distortion of the molecule. This distortion accounts for the observed color changes, as the molecular orbital structure is modified, allowing the complex to stabilize. The spectroscopic data also shows the disappearance of the indigo N-H bonding, as the organic molecules incorporate into palygorskite material. A structural change of indigo to dehydroindigo during heating is suggested by this result. Infrared data confirm the loss of zeolitic water and a partial removal of structural water after the heating process. Evidence of bonding between cationic aluminum and dehydroindigo through oxygen and nitrogen is revealed by FT-Raman measurements at higher dye concentrations.

Ground based high-contrast imaging (e.g. extrasolar giant planet detection) has demanding wavefront control requirements two orders of magnitude more precise than standard adaptive optics systems. We demonstrate that these requirements can be achieved with a 1024-Micro-Electrical-Mechanical-Systems (MEMS) deformable mirror having an actuator spacing of 340 microm and a stroke of approximately 1 microm, over an active aperture 27 actuators across. We have flattened the mirror to a residual wavefront error of 0.54 nm rms within the range of controllable spatial frequencies. Individual contributors to final wavefront quality, such as voltage response and uniformity, have been identified and characterized.

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ABSTRACT"Extreme" adaptive optics systems are optimized for ultra-high-contrast applications, such as ground-based extrasolar planet detection. The Extreme Adaptive Optics Testbed at UC Santa Cruz is being used to investigate and develop technologies for high-contrast imaging, especially wavefront control. We use a simple optical design to minimize wavefront error and maximize the experimentally achievable contrast. A phase shifting diffraction interferometer (PSDI) measures wavefront errors with sub-nm precision and accuracy for metrology and wavefront control. Previously, we have demonstrated RMS wavefront errors of <1.5 nm and a contrast of >10 7 over a substantial region using a shaped pupil without a deformable mirror. Current work includes the installation and characterization of a 1024-actuator Micro-Electro-Mechanical-Systems (MEMS) deformable mirror, manufactured by Boston Micro-Machines for active wavefront control. Using the PSDI as the wavefront sensor we have flattened the deformable mirror to <1 nm within the controllable spatial frequencies and measured a contrast in the far field of > 10 6. Consistent flattening required testing and characterization of the individual actuator response, including the effects of dead and low-response actuators. Stability and repeatability of the MEMS devices was also tested. Ultimately this testbed will be used to test all aspects of the system architecture for an extrasolar planet-finding AO system.

Micro-electro-mechanical systems (MEMS) technology can provide for deformable mirrors (DMs) with excellent performance within a favorable economy of scale. Large MEMS-based astronomical adaptive optics (AO) systems such as the Gemini Planet Imager are coming on-line soon. As MEMS DM end-users, we discuss our decade of practice with the micromirrors, from inspecting and characterizing devices to evaluating their performance in the lab. We also show MEMS wavefront correction on-sky with the "Villages" AO system on a 1-m telescope, including open-loop control and visible-light imaging. Our work demonstrates the maturity of MEMS technology for astronomical adaptive optics.

With its reputation as a high-energy density fuel, aluminum hydride (AlH 3 ) has received renewed attention as a material that is particularly suitable, not only for hydrogen storage but also for rocket propulsion. While the various phases of AlH 3 have been investigated theoretically, there is a shortage of experimental studies corroborating the theoretical findings. In response to this, we present here an investigation of these compounds based primarily on two research areas in which there is the greatest scarcity of information in the literature, namely Raman and infrared (IR) absorption analysis. To the authors' knowledge, this is the first report of experimental far-IR absorption results on these compounds. Two different samples prepared by broadly similar ethereal reactions of AlCl 3 with LiAlH 4 were analyzed. Both Raman and IR absorption measurements indicate that one sample is purely γ -AlH 3 and that the other is a mixture of α-, β-, and γ -AlH 3 phases. X-ray diffraction confirms the spectroscopic findings, most notably for the β-AlH 3 phase, for which optical spectroscopic data are reported here for the first time. Copyright

Although herbal medicine is widely employed in inhibition of urinary calculi as an alternative and complementary curative method, the lack of detailed scientific studies that could provide insights into this complex process weakens its validity. The present work targets multitechnique spectroscopic investigations by Raman, infrared absorption, X-ray photoelectron spectroscopy (XPS), and photoluminescence on the effects of the herb Rotula Aquatica Lour (RAL) on the growth of synthetically prepared magnesium-based calculi. In addition to the standard magnesium phosphate-based sample, two other samples were prepared with incorporation of 1 and 2wt% RAL herbal extract. Both, Raman and infrared data show a newberyite structure for the crystals without and with inhibitor. The XPS measurements reveal an unexpected presence of Zn in the sample with RAL inhibitor, which, as suggested in the literature, may initiate rapid stone formation, and consequently, contribute to the inhibition process. Furthermore, the existence of metallic Zn can explain the reflectance of the incident light observed in the infrared transmission studies of the unground crystals. A significant increase in magnesium with addition of herbal extract is observed in the XPS data. Also, evidence for Mg-O binding between the inhibitor and the phosphate units of urinary calculus is found in XPS and Raman results. Similarity between our photoluminescence measurements and those of in vivo chlorophyll a corroborates to provide additional evidence of Mg-related inhibition.

It is shown how the history of the growth of an icosahedral Zn-Mg-Y single grain can be determined by measuring the yttrium distribution. The growth mechanism and the stabilization of the icosahedral Zn-Mg-Y, RE (RE = rare earth: Ho, Er, Dy, Gd, Tb) quasicrystals are discussed with respect to structural investigations on related crystalline phases. We also show results of optical and ultrasonic investigations on icosahedral Zn-Mg-Y single crystals. They fit well to the discussed growth and stabilization mechanism.