Category: 2011-2017 Highlights

By: S.E. Babcock, T.F. Kuech, L. J. Mawst The presence of chemical species on a surface can radically change the surface chemical kinetics associated with atom placement and crystal growth. Recently, IRG1 researchers at the Wisconsin MRSEC completed a comparative study of the effect on epilayer composition and structural properties of reactant sequencing during the metalorganic …

By: S.E. Babcock, A.S. Brown, T.F. Kuech The nanoscale structural and compositional features of molecular beam epitaxy (MBE)-grown GaAs1−yBiy films have been successfully characterized with unprecedented precision by researchers of the Wisconsin MRSEC using high-resolution x-ray diffractometry and high-resolution high-angle annular dark field (HAADF or “Z-contrast”) imaging in a scanning transmission electron microscope. The spots on …

By: J. W. Spalenka, P. Gopalan, H. E. Katz, and P. G. Evans Solution deposited ZnO films are technologically promising materials with potential applications in large-area electronics on flexible substrates, as transparent circuit elements, and as a transparent electrode materials. However, at small film thicknesses (<50 nm), the regime where transparency and mechanical flexibility are greatest, …

The electronic properties of thin films with thicknesses of only a single molecular layer have in the past typically been far worse than thicker films of the same material.  Recent studies by IRG2 of the Wisconsin MRSEC have now discovered that monolayer-thickness two-dimensional layers of α,ω-dihexylsexithiophene (α,ω-DH6T) exhibit field-effect hole mobility of up to 0.032 …

By: M. Rajendram, H. Tuson, V. Smeianov, K. Ngo, M. M. Cox, D. Weibel Researchers in IRG3 of the Wisconsin MRSEC are studying bacteria to understand principles by which nature designs materials to achieve dynamic spatial targeting of molecules. Recently, the researchers have discovered that the spatial organization of phospholipids at the curved regions of bacterial …

By: IRG2: Wei Xiong, Jennifer E. Laaser, Randy D. Mehlenbacher , and Martin T. Zanni In the last ten years, two-dimensional infrared spectroscopy has become an important technique for studying molecular structures and dynamics. We report the implementation of heterodyne detected two-dimensional sum-frequency generation (HD 2D SFG) spectroscopy, which is the analog of 2D infrared (2D …

In July, 2012, the UW-MRSEC hosted graduate students from the University of Puerto Rico Mayaguez. While in Madison, Wisconsin the students performed their Science on Wheels (Ciencias en Ruedas) show at the Wisconsin Institutes for Discovery on the UW–Madison campus. The show teaches students about chemistry and physics using loud, exciting, highly visual content including …

By: J. W. Spalenka, P. Gopalan, H. E. Katz, and P. G. Evans Solution deposited ZnO films have the opportunity for wide application in large-area electronics on flexible substrates, as transparent circuit elements, and as a transparent electrode material.  However, at small film thicknesses (<50 nm), the regime where transparency and mechanical flexibility are greatest, solution …

The University of Wisconsin – Madison (UW) Materials Research Science and Engineering Center (MRSEC) on Nanostructured Interfaces hosted two national events for museum educators at the Madison Children’s Museum and on the UW campus. The first event, held February 28 – March 2, was a professional development workshop for partners of the Nanoscale Informal Science …

Nanostructures are extremely sensitive to their surface properties. In the past year we have made extensive measurements of thin silicon films in ultra-high vacuum. We now have strong evidence that ultra-thin silicon with a 2×1 surface reconstruction is heavily influenced by the surface pi* band. Fig. A shows experimental measurements (black squares) of the conductance …