Stanford Synchrotron Radiation Lightsource

For the first time, ultrafast x-ray scattering and spectroscopic measurements carried out at SSRL, the Advanced Light Source (ALS) and the Advanced Photon Source (APS) captured the atomic-level dynamics of a superionic nanocrystal as it transformed.

Scientists exploring the physics of hearing have found an underlying molecular cause for one form of deafness. The team, led by Gerard Wong, Professor of Materials Science and Engineering, of Physics, and of Bioengineering at the University of Illinois at Urbana-Champaign, report their findings in the February 2007 issue of the journal Physical Review Letters.

Microtubules, 25 nanometer scale hollow tubules, are critical components in a broad range of functions in eukaryotic cells -- from providing tracks for the transport of cargo to forming the spindle structure for chromosome segregation before cell division. They are used as nanometer scale tracks in neurons for the transport of neurotransmitter precursors and enzymes to synaptic junctions in nerve cell communication.

New evidence is overturning the assumption that the thermal oxide grown on single crystal silicon is completely amorphous. SSRL researchers Anneli Munkholm (now at Lumileds Lighting) and Sean Brennan recently published work in Physical Review Letters showing that there is residual order within the oxide. The thermal oxide film on silicon has been studied extensively for decades because these oxides form the basis of most of the integrated circuits used in modern electronics. The new results have implications for theoretical models of the oxidation process.

Electrocatalysis is the science of modifying the overall rates of electrochemical reactions so that selectivity, yield and efficiency are maximized. Studies in electrocatalysis have resulted in tools such as highly selective multicomponent gas mixture sensors and better electrocatalysts for the fuel cells. Markovic and Lucas have been very active in studying the mechanisms by which these catalysts operate and developing in-situ surface x-ray scattering (SXS) techniques for their studies. 

Organic solar cells, which use organic polymers or small organic molecules to convert sunlight into a useable form of energy, are a promising new tool for providing inexpensive, environmentally friendly energy. To date organic solar cells have demonstrated comparatively low rates of efficiency, stability and strength.  However, there is much room for improvement before the theoretical efficiency limits are reached.

New, designer materials—the ones that can carry a charge without depleting it or offer dramatically faster, more efficient computer memory—take advantage of the interplay between the materials’  degrees of freedom (in other words, the parameters that contribute to the materials’ state).  One such promising material, made of the elements lanthanum, strontium, and manganese, has previously demonstrated unusual magnetic properties depending on the particular mixture of lanthanum and strontium.

Organic semiconductors could usher in an era of foldable smart phones, better high-definition television screens and clothing made of materials that can harvest energy from the sun needed to charge your iPod or iPad, but there is one serious drawback: Organic semiconductors, while inexpensive, do not conduct electricity very well.

Attempting to determine and describe the atomic arrangements in an amorphous material is a daunting prospect. A considerable advance has been made in the anomalous X-ray scattering approach to determining these arrangements in materials containing two atomic species.

The strong electron correlations in transition metal oxides give rise to such phenomena as high-temperature superconductivity in layered cuprates and to stripe-like order in layered cuprates and nickelates. In the case of the manganites, an additional strong electron-lattice interaction leads to a very rich phase diagram in which structural, magnetic, and transport properties are intimately related. Colossal magnetoresistance (CMR) has been observed in the perovskite and double-layer manganites, but not in the single-layer system La_1-xSr_1+xMnO₄ (Mn214).