By performing spatially resolved Raman and photoluminescence spectroscopy with varying excitation wavelength, density, and data acquisition parameters, we achieve a unified understanding towards the spectroscopy signa...
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By performing spatially resolved Raman and photoluminescence spectroscopy with varying excitation wavelength, density, and data acquisition parameters, we achieve a unified understanding towards the spectroscopy signatures of the organic-inorganic hybrid perovskite, transforming from the pristine state (CH3NH3PbI3) to the fully degraded state (i.e., PbI2) for samples with varying crystalline domain size from mesoscopic scale (approximately 100 nm) to macroscopic size (centimeters), synthesized by three different techniques. We show that the hybrid perovskite exhibits multiple stages of structure transformation occurring either spontaneously or under light illumination, with exceptionally high sensitivity to the illumination conditions (e.g., power, illumination time, and interruption pattern). We highlight four transformation stages (stages I–IV, with stage I being the pristine state) along either the spontaneous or photoinduced degradation path exhibiting distinctly different Raman spectroscopy features at each stage, and point out that previously reported Raman spectra in the literature reflect highly degraded structures of either stage III or stage IV. Additional characteristic optical features of partially degraded materials under the joint action of spontaneous and photodegradation are also given. This study offers reliable benchmark results for understanding the intrinsic material properties and structure transformation of this unique category of hybrid materials, and the findings are pertinently important to a wide range of potential applications where the hybrid material is expected to function in greatly different environment and light-matter interaction conditions.
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STERN, HMETZGER, RHoward K. Stern:is presently vice president of Robotic Vision Systems
Inc. He received a bachelor of electrical engineering degree from College of the City of New York in 1960. Mr. Stern joined Dynell Electronics Corporation in 1971 and became part of the Robotic Vision Systems
Inc. staff at the time of its spin-off from Dynell. He was program manager of the various three-dimensional sensing and replication systems constructed by Dynell and Robotic Vision Systems. As program manager his responsibilities encompassed technical administrative and operational areas. The first two portrait sculpture studio systems and the first three replication systems built by Robotic Vision Systems Inc. were designed manufactured and operated under his direction. Before joining Dynell
Mr. Stern was a senior engineer at Instrument Systems Corporation and chief engineer of the Special Products Division of General Instrument Corporation. Prior to these positions Mr. Stern was chief engineer of Edo Commercial Corporation. At General Instrument and Edo Commercial he was responsible for the design and manufacture of military and commercial avionics equipment. Mr. Stern is presently responsible for directing the systems design and development for all of the company's programs.Robert J. Metzger:is currently engineering group leader at Robotic Vision Systems
Inc. He graduated summa cum laude from the Cooper Union in 1972 with a bachelor of electrical engineering degree. Under sponsorship of a National Science Foundation graduate fellowship he graduated from the Massachusetts Institute of Technology in 1974 with the degrees of electrical engineer and master of science (electrical engineering). In 1979 Mr. Metzger graduated from Polytechnic Institute of New York with the degree of master of science (computer science). Since 1974
Mr. Metzger has been actively engaged in the design of systems and software for noncontact threedimensional optical measurement for both military and commercial applications. Of particular note are his c
Ship's propellers are currently measured by manual procedures using pitchometers, templates and gauges. This measurement process is extremely tedious, labor intensive and time consuming. In an effort to provide in...
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Ship's propellers are currently measured by manual procedures using pitchometers, templates and gauges. This measurement process is extremely tedious, labor intensive and time consuming. In an effort to provide increased accuracy, repeatability and cost effectiveness in propeller manufacture, an automated propeller optical measurement system (APOMS) has been built which rapidly and automatically scans an entire ship's propeller using a 3-D vision sensor. This equipment is integrated with a propeller robotic automated templating system (PRATS) and the propeller optical finishing system (PROFS) which robotically template and grind the propeller to its final shape, using the APOMS-derived data for control feedback. The optical scanning and the final shape are both controlled by CAD/CAM data files describing the desired propeller shape. An automated propeller balancing system is incorporated into the PROFS equipment. The APOMS/PRATS/PROFS equipment is expected to provide lower propeller manufacturing costs.
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