Concurrent structural and chemical microscopy
Carol Hirschmugl, UW-Milwaukee
From the earliest experiments with optical microscopes, researchers have examined the images of tissues and microbes. Beyond their visual appearance, knowledge of their chemical makeup would provide great insight into how these structures function. First results from IRENI, a new beamline at the Synchrotron Radiation Center, demonstrate synchrotron chemical imaging that provides unprecedented structural and chemical information simultaneously. The development of this chemically sensitive infrared microscope will greatly expand the ability to examine biological structures, and to track changes over minutes, marking a revolution in synchrotron-enabled science. The new system produces higher quality results than can be obtained with the best commercial systems. These results allow scientists to identify the biochemistry of very small objects in tissue samples, such as single cells (to distinguish if they are inflammatory or not) and important membranes.
NEXAFS spectroscopy of biomimetic dye molecules for solar cells
Franz Himpsel, Physics Dept. UW-Madison
The key obstacle to using sunlight as a significant alternative energy source is the cost to create solar cells. The greatest material and production costs can be removed by replacing the silicon crystal in the solar cell with inexpensive organic dyes. While it is possible to create these “dye-sensitized solar cells” their efficiency is still too poor. If a good dye and synthesis method can be identified then inexpensive solar cells could be mass-produced and our nation would have a viable alternative energy resource that does not pollute at all. By systematically improving organic dyes for solar cells using a feedback loop there is a much better chance that an efficient dye can be identified. Several important aspects of these dyes are easily studied but only if synchrotron light is readily available. Today, the efficiency of dyes has reached a plateau, which is too low to make them economically competitive. Furthermore, the best efficiency is reached with dyes based on an expensive metal (ruthenium). In order to overcome these limitations Himpsel’s group started a systematic investigation of dye molecules using synchrotron light. The ultimate goal is to optimize the molecules used in dye-sensitized solar cells. The preferred dyes contain inexpensive metals, such as iron and manganese, which is used by plants for photosynthesis; and there is a good chance that expensive ruthenium can be replaced.
Disentangling the charge transport mechanisms in organic semiconductors
Hartmut Höchst, Synchrotron Radiation Center
This work sheds light on a decades-old problem of how charges are transported through a crystal consisting of organic molecules. Understanding charge transport through organic semiconductors is key in explaining why these materials are promising candidates for novel electronic applications such as flexible computer displays, spray- or paint-on solar cells, and “printed” electronics, with mass production coming off a rotary printing press rather than by the elaborate and tedious production steps currently involved in the fabrication of electronic circuits. Considering the much simpler manufacturing processes and their comparatively low environmental impact, solar cells based on organic molecules can be a key in solving the world’s energy crisis. Dr. Höchst and his collaborators utilized the tunabilty of the synchrotron radiation in their experiments on Pentacene, a prototypical organic semiconductor, to understand how charges are transported through this material. Furthermore, their experiments on the interaction between charges and lattice vibrations in crystalline Pentacene films demonstrated that vibrations can, astoundingly, both aid and hinder charge transport.
Ultraviolet absorption of the lowest-lying electronic state in high-temperature and supercritical water
Timothy Marin, Benedictine University
Ireneusz Janik and David M. Bartels, Notre Dame Radiation Laboratory
Water is the most familiar liquid substance on this planet but surprisingly many of its fundamental physical and chemical properties are not well understood. Despite decades of research on this deceptively simple molecule, information has been obtained mainly from abstract models designed on computers and experiments done at normal everyday conditions. Experimental data at high temperatures and pressures are sparse. When water is heated beyond its boiling point and simultaneously squashed by intense pressure it does not boil but rather it remains a liquid. This state is known as super critical water (SCW). At this state water behaves much differently than the everyday liquid. For example SCW flows much more easily over surfaces due to a decreased viscosity and it develops an inability to dissolve substances like salts. This project examined how SCW behaves when subjected to ultraviolet radiation. The aims of the project were to gain insight into the fundamental structure of this seemingly simple molecule.
Critical point effects on the quasi-free electron energy
Cherice Evans, Queens College-CUNY and the Graduate Center—CUNY
Gary Findley, University of Louisiana at Monroe
One aspect of investigating various areas of science such as chemical reactions, chromatography, and the creation of high purity nanomaterials is the understanding of solvation in dense fluids. Under extreme pressures and temperatures these fluids start to behave differently as compared to a sample at ambient pressure and temperature. When these substances are pushed to such extremes they can reach their critical point. This project focused on studying several gases such as argon and krypton when they are pushed to their critical points and, more specifically, how conducting electrons in these systems behave under these extreme conditions. This series of investigations has been transformative in providing a new benchmark in the detailed study of how electrons configure themselves in extremely dense fluids. Studies of these dense fluids will lead to further examination of fluids commonly used in chemical reactions, chromatography, chemical separations, and in the synthesis of nanomaterials. Our investigations have revealed much information about near critical point fluids. However, the need to go to lower temperatures to continue these studies has led us to the development of a new technique known as electric field enhanced photoemission (FEP).
DIBSyRCH: The diffuse interstellar band synchrotron radiation carrier hunt
James Lawler, University of Wisconsin
Floating in the deep regions of the Milky Way are massive clouds whose compositions have remained a mystery for nearly a century. A team led by Jim Lawler utilizes the broad range of synchrotron light produced at SRC to help recreate the setting in which the diffuse clouds are found in space. When the clouds are observed their images are converted graphically to create a unique molecular fingerprint known as spectra. These spectra indicate the unknown types of molecules that comprise the large clouds. Since the discovery of the diffuse clouds the suspected constituents of their makeup were narrowed down to a few candidates. The most suspected being hydrocarbons. There are currently more than 100 different molecular species known to exist in deep space and over 300 different molecules that contribute to the diffuse clouds. The diffuse clouds are ubiquitous along many lines of sight in the Milky Way and identification of these molecules would vastly expand our knowledge of molecules in space. The other unknown features found in the clouds are also extensively observed in more distant objects and identifying the molecules responsible for these phenomena would increase the utility of these observations and encourage astronomers to search for additional related features.
FTIR imaging of biological tissues & fungi
Kathy Gough—University of Manitoba
Nearly 30% of people who undergo elective back surgery experience continued discomfort even after several surgeries. Much of this is caused by the formation of scar tissue following these operations. A reduction in scar tissue build-up would result in faster and better wound healing. This would allow patients to return more quickly to a normal quality of life and save money since expensive pharmaceuticals and surgeries would be unnecessary. As part of a Collaborative Health Research Project involving researchers at the University of Saskatchewan and the University of Manitoba we began using infrared radiation to study muscles and how they healed. The experiment later required a more advanced source of infrared radiation, which we found at SRC. In the experiment we examined rats that underwent a type of back surgery called lumbar laminectomy. They were then treated with a control of saline and a chemical known to aid in healing called quercetin (L-2-oxothiazolidine-4-carboxylate (OTC)). The infrared light produced from the FTIR beamline at the SRC allowed us to collect specific data of tissue components on a microscopic scale. These images showed differences in the distributions of proteins (collagens), fats (lipids), and sugars in the developing scar tissues.
Microfocus angle-resolved photoemission facility
Tom Miller, University of Illinois (in collaboration with SRC)
SRC utilizes an array of beamlines to manipulate the wide variety of light frequencies that come out of the accelerator. A common method for using synchrotron radiation to conduct materials research experiments is known as Angle-Resolved Photoemission Spectroscopy (ARPES). This project sought to enhance an ARPES beamline at SRC to make the spot of light coming out of the beamline smaller and more focused. This increased precision will show more of a sample’s details, which would otherwise be glossed over by a larger spotsize, will help scientists better understand the properties and behaviors of the materials they are researching. Angle-resolved photoemission has been a workhorse for solid-state research for many years, but its applicability has been typically limited to samples of larger dimensions by the available light beam size. This new system could have broad scientific impact on numerous material systems of general interest and the activity leverages the creation of knowledge and technical expertise that will be generated by users of the facility in the course of their research. The goal of this activity is to advance the research and education infrastructure at SRC. Strong participation by students will contribute to the technical training critically needed for the nurturing of future generations of leaders, users, and machine and instrument builders of light sources.
Observations of a kink in the dispersion of f-electrons
Tomasz Durakiewicz, Los Alamos National Laboratory
In every electronic device a noticeable amount of the electricity flowing through it is wasted. As electricity flows through the device it encounters resistance that heats up the device and prevents it from performing optimally. This issue can be solved by a physics phenomenon known as superconductivity, which is what happens when matter becomes so cold that all electrical resistance disappears. With no resistance there is no heat and the electricity can flow much more efficiently. The main hurdle in maintaining a superconducting state is then need to maintain extremely low temperatures such as -321°F, which is costly. The benefits of superconducting materials are apparent when looking at the efficiency of power transmission through the electric grid. Currently the combination of inefficiencies in power production combined with running the electricity through thousands of miles of wire results in less than 30% efficiency. Using synchrotron radiation produced at SRC a team from Los Alamos National Laboratory studied the electron configurations of a handful of different materials such as uranium compounds. These observations resulted in witnessing peculiar behaviors and patterns in these material's structures, which have potential connections to creating higher temperature superconductors. Having a substance that can remain in a superconducting state at warmer temperatures reduces the cost, makes streamlining this technology more feasible, and will lead to great energy savings.
Studies of novel magnetic materials for spin-electronic devices
Patrick LeClair (University of Alabama)
Arunava Gupta (University of Alabama)
Gregory Szulczewski (University of Alabama)
Using x-rays produced at SRC the researchers probed samples of certain materials such as chromium dioxide (CrO2), lanthanum strontium magnesium oxide (LSMO), and cobalt (Co) to study how they reacted magnetically on an atomic scale. This knowledge could lead to continued advances in electronic and magnetic devices. The benefits of research like this are inside every single hard disk drive, and understanding the magnetic properties of materials can lead to faster computers. We feel that in the area of magnetoelectronics, also known as spintronics, which studies the intrinsic nature of electrons for their electronic properties, our work has significant consequences both experimentally and theoretically. This work primarily aims at combining the unique magnetic properties of chromium dioxide and other materials into devices that are expected to exhibit novel phenomena, and which also have exciting real world applications such as magnetic field sensors in hard disks, magnetic random access memory (RAM-computer memory) and rapidly programmable logic arrays. While spintronics has already revolutionized the data storage industry, the fruits these studies are now inside every hard disk drive on the market, the amazing potential of these materials has not yet been developed.