REU Summer 2003

Student Projects

Student Information	Photograph	Abstract
Muhammand Ali of UNLV, working with Prof. James Selser on "Deconvolution of Brillouin Spectra."		Solid polymer electrolytes are being used in rechargeable lithium-polymer batteries that represent state-of-the-art power. Studying the behavior of the polymer electrolyte is key to understanding the ion transport and conductivity inside the actual battery. The samples being studied are solutions of poly(ethylene oxide) melts with and without dissolved lithium perchlorate. Employing a fiber-optic coupled Fabry-Perot (F-P) interferometer and a photomultiplier tube, Brillouin scattering is observed from both PEO-1K melts and PEO-melt/ LiCLO4 solutions. Determining the true shape of the Brillouin peak is crucial to extracting valuable information about the polymer electrolyte. Therefore the F-P instrument function must be deconvolved from the scattered light spectra. Fourier and fast-Fourier transform methods are not ideal for this particular deconvolution because of their sensitivity to noisy measurements. Instead, a program based on Bayes Theorem is being developed to deconvolve the observed spectra to obtain accurate Brillouin peak shapes so that accurate measurements such as the FWHM values for the Brillouin peaks can be determined. In turn, the FWHM values can provide valuable information about PEO electrolytes.
Anthony Carcelli of UNLV and Eric Cardoza of California State University, Fresno, working with Prof. Victor Kwong on "Modifications to a Preexisting RF Ion Trap System Utilizing Microprocessor Technology."		The current system consists of 12 separate TTL pulse generators that drive the ion generation, collection, and analytic processes in the ion trap system. These pulse generators will be replaced with a PIC16F877 microprocessor and task-specific software. After designing software to interface with the new microprocessor, system improvements will include: smaller ion sampling intervals, faster rise times, shortened signal transmission delays, adjustable pulse widths, and the ability to load and save presets. In addition, the length and number of transmission cables between TTL boxes will be minimized through the construction of a single consolidated rack-mounted unit. An RF voltage comparator has also been redesigned for faster reaction times and integration with the new system.
Tim Dutton of Radford University, working with Prof. Andrew Cornelius on "The Production of an AC Susceptometer for use in the Pulse Tube Cryostat."		This Summer's work is to create, from scratch, a device to measure the magnetic suscepability of a material inside our low temperature machine. This has involved coming up with a design that will fit inside the machine beingused and will perform the measurement. To date we have finished the designing process and are nearing completion of building the device. Remaining tasksfor the summer include calibrating and testing our device.
Matthew Efseaff of Willamette University and Sandra Penny of University of Oregon, working with Prof. David Shelton on "Long Range Molecular Interactions in Water."		Previous experiments have arrived at relatively inconclusive results as to the exact spectral width of polarized Hyper Rayleigh Scattered light in liquids, but have given a estimate of expected spectral widths. Data gathering is limited by instrumental capabilities because of variables such as thermal expansion of the instrument itself and the inability of the drive to scan smoothly over a small distance. Efforts have been made in order to reduce the inconsistencies in the spectrometer so that long term data gathering can be precise enough to adequately determine spectral shapes. It is our eventual goal to continue previous research on the long range molecular dipole correlations in deuterated water.
Chris Harland of University of Puget Sound and Stacy Sidle of Rhodes College, working with Prof. John Farley on "Investigation of Analysis Techniques Associated with Stainless Steel Corrosion."		We are currently exploring analysis techniques pertaining to the corrosion of 316 and 316L stainless steel by lead bismuth eutectic (LBE) in an effort to determine the plausibility of using LBE as a spallation target and blanket coolant for nuclear waste reduction. We exposed 304 stainless steel samples to aqueous nitric and sulfuric acid solutions to identify the form of corrosion that takes place as well as the thickness of the oxide layer on the steel (believed to be on the order of 1 micron). In addition, we copper-plated 304 steel samples to investigate the copper layer's effectiveness in protecting the oxide layer during sample preparation involving metallographic cuts. The copper-plated steel samples were also exposed to nitric and sulfuric acid solutions to determine the copper layer's ability to protect the oxide layer against corrosion. Throughout the course of these investigations we have made extensive use of a scanning electron microscope (SEM) and energy dispersive x-ray analysis (EDAX). Moreover, we have become familiar with high resolution optical microscopy and x-ray photoelectron spectroscopy (XPS). Our future tasks include comparing our SEM images and EDAX spectra to existing data and exploring new analytical techniques such as Raman spectroscopy.
Garret May of University of New Orleans and Zachary Trautt of Colorado School of Mines, working with Prof. Malcolm Nicol on "High Pressure Studies of Sulfur."		Our REU experience constituted learning the basics of high-pressure physics and investigating sulfur at high-pressure. The basic activities of high-pressure physics includes, but is not limited to, pressurizing a sample in a diamond anvil cell, determining pressure with the know fluorescence changes of ruby, finding positions of atoms and the dimensions of crystal structures using x-ray diffractometry, and probing the vibrational energies of bonds in a crystal structure using Raman Spectroscopy. Sulfur was studied because it assumes a molecular structure at ambient conditions, a simple cubic structure near 100 GPa, and information is still needed in the intermediate region.
Rob Pepin of Gonzaga University, working with Prof. Andrew Cornelius.		Using the Physical Property Measurement System (PPMS) by Quantum Design, heat capacity measurements on terbium titanate (Tb2Ti2O7) were taken at low temperatures at various magnetic field strengths. Temperatures ranged from 20 Kelvin (K) down to about 0.36 K. The magnetic field ranged from 0 to 9 Tesla (T). From the heat capacity data collected on this compound we were able to postulate about how the compound orders magnetically when it reaches low temperatures in high fields. From the nuclear heat capacity we were able to extrapolate the internal magnetic field at the terbium nucleus.