September 17, 2008

NSLS Summer Student Projects Range from Crystallography to Detector Development

Eleven college students performed summer research projects at the NSLS this year, working with scientists and engineers from the department in research fields ranging from medical sciences to electrical and mechanical engineering. In addition to their research projects, students had the opportunity to attend scientific lectures, tour Brookhaven’s research facilities, and participate in numerous social activities.

Interested students apply to these programs in the spring, and the programs range from six-to-10 weeks long. More information and application procedures can be found on Brookhaven’s Office of Educational Programs website.

Here’s an idea of what this year’s students did this summer:

Ryan Bonaparte

Ryan Bonaparte will be a senior at the Massachusetts Institute of Technology in the fall. This summer, he worked at the NSLS with Ken Evans-Lutterodt and Christie Nelson on two different projects. For the first project, Bonaparte and Nelson used NSLS beamline X16B to perform x-ray diffraction scans to probe the lattice structure of ferromagnetic manganite films. By learning the exact lattice parameters, they hoped to determine how a change in the substrate would manifest itself in the overlying film layer. For the second project, Bonaparte worked with Evans-Lutterodt on the setup of spectrographic equipment that will soon be mounted at beamline X13B to take fluorescence measurements off of x-ray illuminated samples.

Brett Guralnick

Brett Guralnick recently graduated from Northeastern University and will attend the University of Delaware in the fall to pursue a Ph.D. in chemical engineering. As part of the U.S. Department of Energy’s Science Undergraduate Laboratory Internship (SULI), he worked with Darío Arena at beamline U4B on x-ray magnetic circular dichroism (XMCD). They collaborated with William Bailey from Columbia University to study a change in magnetic anisotropy (revealed by a change in the magnetic easy axis) when ferromagnetic resonance (FMR) is applied to a multiple layer thin film of permalloy (Py, an iron-nickel alloy), copper, and cobalt zirconium (Co-Zr). XMCD is particularly useful as it can separately examine the magnetic anisotropy of the Py and the Co-Zr layers. An engineering reason to study the FMR of materials is to understand the properties of soft ferromagnets (FM). These ferromagnet materials in thin-film form are used today in applications such as computer hard drives and spintronic devices. For instance, the magnet procession limits the read/write speeds of a hard drive to the range 1-10 GHz. Understanding the precessional dynamics, anisotropy changes, and changes in the material structures can lead to an increase in the limits currently imposed by the materials used today.

Terrell Johnson

Terrell Johnson, an electrical engineering graduate student at the University of Maryland, worked at the NSLS this summer as a GEM Fellow, supported by Brookhaven through the National Consortium for Graduate Degrees for Minorities in Engineering and Science, Inc. Johnson, who is interested in image processing, worked with Pete Siddons to develop a detection system capable of imaging the elemental constituents of paintings and similar media. Painting over photographs is a technique used by an artist for producing replicas and art studies of their works, even the original composition itself. The idea of detecting the photograph is based upon knowing its composition; the photograph is assumed to be created by the common gelatin-silver process, in which a suspension of silver salts in gelatin is coated and dried onto a medium (film, fiber, resin paper, etc.). The underlying picture is projected using methods for elemental imaging and energy dispersive detection. The detector uses x-rays to uncover the presence of silver, whose florescence spectra can be mapped using spectra deconvolution. The detection of the photographic substrates would answer questions of authenticity and authorship, as well as provide other information crucial to researchers and historians in the field.

Maria Michta

Maria Michta began a Ph.D. program in biomedical science this summer at the Mount Sinai School of Medicine. As an NSLS summer student working with Vivian Stojanoff, she learned the ins and outs of x-ray crystallography. Crystallography is a technique used to calculate the specific arrangement of atoms within a sample to understand its structure. Ultimately, a crystal is bombarded with x-rays to produce a diffraction pattern, which is translated into detailed structural information. Unfortunately, crystals are subjected to radiation damage from the x-rays much in the same way human skin is susceptible to UV radiation from the sun. Michta studied how to prevent radiation damage of crystals, or, in other words, search for the perfect SPF for crystals.

Steven Mon

Steven Mon, a senior at Columbia University majoring in electrical engineering and minoring in materials science, was a SULI intern this summer under the co-mentorship of Raluca Gearba and Chuck Black of the Center for Functional Nanomaterials (CFN) and Ron Pindak of the NSLS. His research project focused on the fabrication and characterization of organic photovoltaics (OPVs). With growing global energy needs, there is an impetus for the development and deployment of renewable energy, of which solar energy is an essential component. Compared to conventional inorganic solar cells, OPVs are potentially easier to fabricate, lower cost, lighter, can be fabricated on flexible substrates, but their efficiencies are relatively low at a bit over 5 percent. The goals of the research group are to understand the factors limiting the efficiencies of the OPVs and ultimately to develop more efficient solar cells. Mon’s summer project studied how thiol additives affect phase separation, nanostructuring, and efficiencies in polythiophene-fullerene bulk heterojunction (BHJ) solar cells and then explored the fabrication and characterization of pentacene-perylene BHJs. He used the NSLS to characterize the internal structure of the devices fabricated, which is a challenge due to the nanometer scale of these devices.

Christopher Owen

Christopher Owen, a sophomore at SUNY Buffalo pursuing a double major in chemical and electrical engineering, worked at the NSLS with Vivian Stojanoff this summer to develop new instrumentation for beamline X6A. Working in collaboration with Tony Kuczewski and Peter Siddons, Owen constructed a new beam-position monitor to replace the current ion chamber that monitors the incident beam on the sample. Along with new software, the upgraded position monitor will allow for continuous monitoring of the beam position on the sample and assist in the automated alignment of the beamline with the x-ray beam. Owen also prototyped circuitry to control an air-pressure-activated beamline shutter. Other projects include the calibration of a fluorescence detector to detect minute metal concentrations used as markers in protein crystal samples. With the new and upgraded equipment, experimenters will have an easier time collecting data and will be able to perform more tests during their visits at the NSLS.

Vontrelle Collins, Marcus Walker and professor Elhag Shaban

Students Vontrelle Collins and Marcus Walker and professor Elhag Shaban, from Southern University, worked at the NSLS this summer with Pete Siddons as part of the Faculty and Student Team program. The group worked on a specialized gas electron multiplier (GEM), which is used to amplify a very small signal into a very large signal in order to reduce noise. The GEM acts as a capacitor because it is made from two copper plates with an insulator in between and perforated holes for electron amplification to occur. The multiplication of electrons is done by ionizing radiation using x-rays that create an electron avalanche. The group’s gas detector consists of three GEMs back to back, so that an amplification of about 1 million electrons can be achieved. The Micromesh Gaseous Structure (MicroMegas) was added to two GEMs to get a better signal gain to reduce the noise that masks the signal.

Andrew Ying

Andrew Ying, a graduate student at Columbia University, is interested in determining local size and strain information in materials using x-ray diffraction techniques. At the NSLS this summer, he worked with Ken Evans-Lutterodt in commissioning experiments at beamline X13B. The goal is to enhance the usability of the beamline so future users can minimize time during experimental setup and maximize time in data collection. Currently, the beamline is equipped with gold KB mirrors used to focus down to a 2 x 4 micron spot size while maintaining the high flux from the undulator source. The group installed downstream optics that help hasten focusing and also serve in preliminary diffraction contrast imaging studies. Ying also semi-automated the charge-coupled device (CCD) distortion correction that will allow for quicker and more accurate CCD orientation. In addition, a 2-theta point detector was installed. Upon completion of these tasks, X13B will be a premier beamline for local strain measurements in materials at the NSLS.

Christina Zayas

As a freshman in physics at Stony Brook University, Christina Zayas decided to follow an internship in her spring semester at the NSLS in the hopes to explore different applications and career opportunities in physics. This summer, Zayas returned to work on beamline X15B, under the direction of Paul Northrup and Vivian Stojanoff, to collect and analyze absorption data for various proteins containing metal centers. Primarily, her objective was to establish the local environment of the absorbing atom in order to determine how electrons are transferred during the catalytic action of different enzymes. In the future, Zayas aspires to continue research in x-ray absorption spectroscopy and pursue graduate study in applied physics or material science.