Grant Number: 8T8003

Plutonium Speciation as Determined by Molecular Modeling

David Graf
Buffalo State College
SURF Student, Ionizing Radiation Division

Michael Schultz
Advisor
Guest Researcher, Ionizing Radiation Division
NIST Physics Laboratory


ABSTRACT

My project was to use ab initio molecular orbital theory to figure out how Pu species formed in various environmental conditions. All calculations were done using Gaussian, a quantum chemistry program. Once I found that PCs were far too limited, the calculations were done on NIST's supercomputing systems (CRAY, SP2,...). Working with actinides in this way is relatively new and models, when completed, could prove to be useful for determining bioavailability and mobility of actinide complexes. Since many of these species are radioactive and potentially harmful, accurate models could help reduce health hazards.

Biographical Information:

(For the 4 millionth time...) My name is David Graf and I go to Buffalo State College in New York. I will graduate with a BS degree in Physics in December, and I am looking into grad school for next fall (possibly at LSU). I have done previous research in the Mossbauer Effect using ₁₁₉Sn to determine lattice softening in alloys. I will most likely continue to do this type of work in the fall.

Mailing Address:

46 Greenwood Circle
North Tonawanda, NY 14120

Grant Number: 6T6021

The NLSE of the WIDTBG:GP and BEC
Or
A Numerical Solution to the Gross-Pitaevskii Equation

Rina Lim
University of California-Irvine
SURF Student, Electron and Optical Physics Division

Charles W. Clark
Advisor
Chief, Electron and Optical Physics Division
NIST Physics Laboratory


ABSTRACT

We are numerically solving the Gross-Pitaevskii equation for Bose condensed sodium atoms in a spherical trap, precise to twelve orders of magnitude. To do this, we approximate the function by the Thomas-Fermi solution corrected by an exponential tai. Once a well-defined boundary condition is obtained, we can numerically integrate the differential equation. Successful results have been obtained for 16,000 and 160,000 atoms.

Mailing Address:

Grant Number: 8T8017

Metallurgy of Metal Contacts to GaN

Dawn Nida
University of Florida
SURF Student, Metallurgy Division

Albert Davydov
Advisor
Guest Researcher, Metallurgy Division
NIST Materials Science and Engineering Laboratory


ABSTRACT

I will talk about the interfacial reactions and the correlation with the ternary Ga-N-Ti phase diagram in determining the quality of contact of metal contacts to GaN. The two aspects of reactions and phase diagram were studied to better understand the nature of contact formation in the Ti/GaN/sapphire system. A thorough understanding of these contacts is important for UV and blue optical devices, and high temperature/high power devices.

The nature of metal contacts to GaN is not fully understood. There is no existing data on the phase diagram of Ga-Ti-N (experimental) that is known to have been published. The only information existing for the Ga-Ti-N system was based upon thermodynamic calculations not experiments (Chang). There is a definite need to understand this system because of its applications in UV/visible optoelectronic devices and high temperature/high power electronic devices.

Phase diagram studies coupled with interfacial reactions studies were conducted. The phase diagram study resulted in the possibility of a new phase "Ti3GaN." The research also allowed for the determination of decomposition reactions and corresponding temperatures for Ti₂GaN and "Ti₃GaN" ternary compounds. The interfacial reaction study showed a correlation between heat-treatments in different ambient atmospheres and the order of the phase formation.

In my presentation, I will outline the importance of my research and a background. I will then discuss the specifics of both my interfacial research and the phase diagram study and how they relate. Pictures will be included to illustrate the results of the interfacial study, entirely SEM pictures. Conclusions will then be given.

Biographical Information:

I graduated from the University of Florida with a BS in materials science and engineering. I will be attending North Carolina State University in the fall for graduate school. I plan to get my Ph.D. there in materials engineering under Dr. Robert Davis. I then plan on going to medical or dental school or further engineering studies.

Mailing Address:

5710 Oak Meadow Lane
Apartment 2512,
Raleigh, NC 27612

Grant Number: 8T8020

Optical Pumping Methods and Analysis in Spin Polarization of 3He

Andrew Lee
Bucknell University
SURF Student, Ionizing Radiation Division

Thomas Gentile
Advisor
Physicist, Ionizing Radiation Division
NIST Physics Laboratory


ABSTRACT

The large spin-dependent cross section for absorption of neutrons by ³He allows polarized ³He to be used as a neutron polarizer or analyzer. Polarized ³He is produced using two different techniques: rubidium spin-exchange optical pumping and metastability-exchange optical pumping. For the thickness required for polarizing cold neutrons (5 to 10 atm-cm), both of these techniques can currently provide spin polarization up to 45%. The ³He polarization can be measured by using NMR (nuclear magnetic resonance) techniques or, in the case of the metastable method, an optical technique can be employed. The design, construction, and results for the optical polarimeter will be presented.

Polarized ³He gas created is now being used in neutron experiments at the NIST reactor to polarize or analyze neutron beams in preliminary experimentation. A ³He-based analyzer was recently used to measure the polarization of a non-monochromatic neutron beam that was polarized through conventional super-mirror techniques. In this case, the simple analytic formulas that are valid for a monochromatic beam cannot be applied. A numerical model for extracting the neutron polarization will be discussed.

Biographical Information:

Andrew is a senior B.S. physics major at Bucknell University. After graduation he will enter a Ph.D. program in physics. His areas of interest focus primarily on non-linear dynamics and atomic and molecular physics. Andrew would like to eventually return to the academic profession as a research professor. During his spare time he enjoys working on classic cars and traveling.

Mailing Address:

C3360 Bucknell University
Lewisburg, PA 17837

Grant Number: 8T8023

Providing Sample Environments for Neutron Scattering Experiments

Syed Rauf
Montgomery College
SURF Student, Reactor Division

Jeffrey Lynn
Advisor
Physicist, Reactor Division
NIST Materials Science and Engineering Laboratory


ABSTRACT

My talk will be mainly based on the importance of sample environment in neutron scattering experiments, and how we produce these controlled environments. In particular, I will talk about Helium Gas Refrigerators, Standard Vacuum Furnace and Temperature Controllers. I am working at Neutron Research Facility with the group that provides sample environments for the experiments at the Neutron Research Facility.

Biographical Information:

Hometown is Olney, Maryland. I will be attending Montgomery College, Rockville as a sophomore this semester. I am planning to transfer to University of Maryland, College Park next year. My major is Electrical Engineering but now I am thinking about doing a double major in EE and Physics.

Mailing Address:

4916 Continental Drive,
Olney, MD 20832

Grant Number: 8T8016

Scanning Probe Microscopy of Ferroelectric Thin-Films


Joshua Hertz
Alfred University
SURF Student, Ceramics Division

John Blendell
Advisor
Materials Research Engineer, Ceramics Division
NIST Materials Science and Engineering Laboratory


ABSTRACT

Ferroelectric thin-films are being considered for use as the primary component in new, non-volatile, high-density computer memory. One of the main factors delaying their use is the degree to which we can control the domain structure. The purpose of this experiment was to implement a non-destructive method of evaluating the structure of the ferroelectric domains in the films. This was to be done using an AC electric field to cause piezoelectric vibrations in the sample, and determining the magnitude and phase of the vibrations at the sub-micron level with a scanning probe microscope. The method has not been fully completed.

Biographical Information:

I am a member of Tau Beta Pi and Keramos, the ceramic engineering honor society. I am also involved in Alfred University's student branch of the American Ceramic Society. I will graduate in December 1999 with a B.S. in Ceramic Engineering, concentration in Electronic Ceramics. After graduation I plan to continue on to graduate school for my Ph.D. in Materials Science.

Mailing Address:

1537 Powell Campus Center
Alfred, NY 14802

Grant Number: 8T8010

Mapping the Magnetic Field of SURF III


Rebecca Friedman
Union College
SURF Student, Optical Technology Division

Keith Lykke
Advisor
Research Chemist, Optical Technology Division


ABSTRACT

The magnetic field of the synchrotron must be as uniform as possible in order to provide a more direct beam of light that can be maintained for a longer life span. The magnetic field is controlled by a set of current coils and large magnets positioned around the storage ring. A uniform magnetic field is achieved through a process of trial and error, by positioning shims of different thickness and lengths.

Biographical Information:

My hometown is Rochester, NY. I am double majoring in physics and philosophy and will graduate from Union College in Schenectady, NY in the year 2000. I plan to go to medical school after college.

Mailing Address:

77 Westland Avenue
Rochester, NY 14618

Grant Number:

Determination of the Complete Sequence of the Mitochondrial DNA from an
Individual with Leber's Hereditary Optic Neuropathy

Kathyrn Kapfer
University of Maryland
SURF Student, Biotechnology Division

Barbara Levin
Advisor
Biologist, Biotechnology Division

Henry Rodriguez
Advisor
Biologist, Biotechnology Division
NIST Chemical Science and Technology Laboratory

Biographical Information:

Katie Kapfer is going to be a junior this fall at the University of Maryland. I am majoring in microbiology. I am from Chicago, IL and am attending Maryland on an athletic scholarship.

Grant Number: 8T8013

Phase Equilibria Relationships in the CaO-Al2O3Nb2O5 System

Wilma Febo
University of Puerto Rico
SURF Student, Ceramics Division

Terrell Vanderah
Advisor
Supervisory Research Chemist, Ceramics Division
NIST Materials Science and Engineering Laboratory


ABSTRACT

Dielectric ceramics for wireless communications exhibiting modest permittivity, high quality factor (Q), and near-zero temperature coefficient are needed for high-frequency, high-power applications. Efforts are in progress to replace Ta₂O₅-based ceramics with less costly oxides that exhibit similar properties. Phase equilibria relations in the CaO-Al₂O₃-Nb₂O₅ system were therefore determined.

Thirty-two samples were prepared by solid-state reaction of the component oxides at 1300-1400= ºC in air until equilibrium was attained. X-ray powder diffraction was used to determine whether equilibrium conditions were reached after multiple heatings, and to identify the resulting phase fields. The only ternary compound found to occur in the system is Ca₂AlNbO₆, which is likely isostructural with Ba(Zn_1/3Ta_2/3)O₃. Ca₂AlNbO₆ reportedly exhibits a permittivity of 25 and a negative temperature coefficient. This compound may adopt the 1:1 ordered perovskite structure, A₂B=B₄B=B₄=B₄O₆ (A=3Dca²⁺), wherein the octahedral B=B4 and B=B4=B4 ions (Al³⁺and Nb) are arranged as in NaCl.

No solid solutions were found in the system possibly due to the difference in size between Al³⁺and Nb⁵⁺ (0.39 and 0.48 =C5, respectively). This result contradicts a previously published Al₂O₃-Nb₂O₅ binary phase diagram, which reported extensive solid solution around AlNbO4. No new compounds were found. Dielectric property measurements are in progress to measure the Q-value for a Ca₂AlNbO₆ at microwave frequencies, and to estimate the permittivities and temperature coefficients of the seven compounds found to occur in equilibrium with it. If any of these compounds exhibit positive temperature coefficients, the phase diagram may be used to prepare temperature-compensated Ca₂AlNbO₆ mixtures for practical applications.

Biographical Information:

Wilma Febo is a Chemistry major; will be a fourth year student next year. I plan to graduate in December 1999, then go to graduate school.

Grant Number: 8T8014

Investigation of the Morphology of Semicrystalline
Polymers by Small Angle X-ray Scattering, Differential Scanning Calorimetry, and Hot Stage Optical
Microscopy

Ankit Patel
University of Maryland
SURF Student, Polymers Division

John Barnes
Advisor
Physicist, Polymers Division
NIST Materials Science and Engineering Laboratory


ABSTRACT

Understanding polymer morphology and microstructure is vital to the development of improved, more economical, and more environmentally friendly products. The work reported here uses Small Angle X-ray Scattering (SAXS), Differential Scanning Calorimetry (DSC), and Hot Stage Optical Microscopy as investigative techniques to determine polymer microstructure and thermal behavior. This study explores lamellar microstructure, a common feature of semicrystalline polymers, through simple modeling of SAXS intensity curves. Hot Stage Optical Microscopy is utilized to investigate the growth of spherulitic aggregates of lamellae, and thermal properties are characterized using the DSC technique. These techniques are performed using poly(propylene), poly(chlorotrifluoroethylene), and poly(4-methylpentene) as the raw materials.

Biographical Information:

I am from Germantown, MD, and will be beginning my sophomore year at the University of Maryland, College Park, this fall. I am currently pursuing a Bachelor of Science degree in Chemical Engineering and plan to continue my studies after graduation and eventually earn a Doctorate in the field.

Mailing Address:

19059 Highstream Drive
Germantown, MD 20874

Grant Number: 8T8009

Radioactive Soccerenes: The Development and Production of ¹²⁵I Radioendofullerenes

Katharine Rowley
Miami University (Ohio)
SURF Student, Ionizing Radiation Division

Michael Mitch
Advisor
Physicist, Ionizing Radiation Division
NIST Physics Laboratory


ABSTRACT

The purpose of this work was to develop a protocol for the production of ¹²⁵I radioendofullerenes. First, classic fullerenes were produced in the Fullerene Production Chamber (FPC) using high-current arc burning of graphite rods. The extraction and purification of fullerenes was accomplished by stirring the soot in CS2, followed by filtration and High Pressure Liquid Chromatography (HPLC). HPLC separated the different fullerene species, which were identified by their optical absorption spectra. After separation, the classic fullerene fractions, in addition to previously produced I@Cn fractions, were analyzed by Time-of-Flight Mass Spectrometry (TOF-MS) to determine if the iodine had successfully been encapsulated. Data analysis of over 250 spectra revealed "shrink-wrap" fragmentation sequences, thus providing strong evidence for endofullerene formation. Various production and extraction techniques were investigated in order to determine the optimum yield of fullerenes for production of ¹²⁵I@Cn. A trial experiment using "cold" iodine (¹²⁷I) was performed to test the protocol. After minor adjustments, the encapsulation of ¹²⁵I within fullerenes was conducted. Purification and analysis of radioendofullerene species is currently in progress.

Biographical Information:

I am native of Eagan, Minnesota just south of St.Paul/Minneapolis. I am currently a junior Physics major at Miami University in Oxford, Ohio and I am planning on attending medical or law school after graduation. I also enjoy jogging, rollerblading and travel in my spare time.

Mailing Address:

4847 Safari Pass
Eagan, MN 55122

Grant Number: 8T8018

Neutron Reflectometry

Akhil Shah
University of California-Irvine
SURF Student, Reactor Division

Sushil Satija
Advisor
Physicist, Reactor Division
NIST Materials Science and Engineering Laboratory


ABSTRACT

Neutron reflectometry has become a powerful tool for investigating surface and interfacial phenomena over the last 15 years. Specular and off-specular neutron scattering are used to derive various characteristics of the material under study. The Cold Neutron Reflectometer at NIST uses a horizontal sample geometry and a Position Sensitive Detector (PSD) to observe both specular and off-specular scattering simultaneously. Generally a data set consists of Q values, both normal and in-plane components, and the corresponding intensity values recorded by the PSD. In this project I have written a Matlab program that will derive these intensity values at user-chosen Q values within the range of measured Q values, incorporating one of Matlab's interpolation routines. Furthermore one can interpolate intensity values over a sample of Q-space (as opposed to just a single vector of Q components) and integrate these values to obtain a better statistical measure. In order to reduce "noise" within the interpolated and integrated intensity vector, we have used a Savitzky-Golay digital filter.

Biographical Information:

I am a physics and electrical engineering major at UC Irvine, and will start my third year this coming fall. I permanently reside in Milpitas, CA, in the heart of Silicon Valley (or at least near a major artery). I hope to attend graduate school in physics, somewhere in CA, and eventually teach at the university level.

Mailing Address:

273 Moretti Lane
Milpitas, CA 95035

Grant Number: 8T8009

Tight-Binding Approximations for CdS/HgS Quantum Dot Quantum Wells

Susan E. Burke
Miami University (Ohio)
SURF Student, Atomic Physics Division

Garnett Bryant
Advisor
Physicist, Atomic Physics Division
NIST Physics Laboratory


ABSTRACT

Tight-Binding Theory can be effectively used to calculate Electron and Hole States in spherical CdS/Hgs Quantum Dot Quantum Wells. The electron and hole energy values are comparable to those calculated for similar structure using Multiband Theory. However, hole level mixing and the resulting state degeneracies are dependent on the QDQW atomic symmetry in the tight-binding model, and are not easily compared to the calculations done with Multiband Theory.

Biographical Information:

I am currently a fourth-year physics major at Miami University, Ohio. After graduating in May, I plan on pursuing a Ph.D. in theoretical physics. This is my second summer working in the Atomic Physics Division here at NIST under Dr. Garnett Bryant.

Mailing Address:

5669 Muddy Creek Road
Cincinnati, Ohio 45238

Grant Number: 8T8015

A Study of the Remagnetization Process in Nanostructured Magnetic Exchange Springs

Zach Hilt
Miami University (Ohio)
SURF Student, Metallurgy Division

Robert Shull
Supervisory Metallurgist, Metallurgy Division
NIST Materials Science and Engineering Laboratory


ABSTRACT

Magnetic exchange springs are made by combining a "hard" and a "soft" ferromagnetic material, thereby creating spring-like interactions between the two dissimilar constituents. This study was conducted on two sets of magnetic exchange spring samples made at the Argonne National Laboratories. The first set were bilayers of 350 Å Sm-Co (hard ferromagnet) topped with 300 Å of Fe (soft ferromagnet), which were epitaxially grown on either a MgO (100) substrate or on a MgO (110) substrate. This epitaxy induces a four-fold magnetic anisotropy in the one grown on MgO (100) and a two-fold anisotropy in the one grown on MgO (110). The second set of samples was similar to the first set, except that the thickness of the Fe layer was increased to 500 Å. The magnetic characteristics of the two sets were investigated using a Superconducting Quantum Interference Device (SQUID) and a Vibrating Sample Magnetometer (VSM). The occurrence of magnetic domains and their motion during remagnetization of the sample into the opposite direction was examined using the Magneto-optical Indicator Film (MOIF) technique. This combination of measurements and observations gave insight into the remagnetization mechanism of these thin films and provided a better understanding of the origin of their spring-like characteristics.

Grant Number: 8T8009

Reflectance and Transmittance: A Matter of Appearance

Ryan Smith
Miami University (Ohio)
SURF Student, Optical Technology Division

Maria Nadal
Advisor
Physical Scientist, Optical Technology Division
NIST Physics Laboratory


ABSTRACT

Appearance can be broken down into two attributes: geometric or spatial, and chromatic. The geometric refers to the gloss, haze, and/or texture of a surface, while the chromatic attribute refers to the color analysis of the surface. This summer I had the experience of dealing with both of these attributes in the laboratory. Under the geometric attribute, my project was to refurbish the NIST hazemeter, and study the data acquisition and reduction of this instrument. Under the Chromatic attribute, I analyzed a set of BCRA series II color tiles, These tiles were checked for uniformity and color.

The Measurement and Analysis of Color and Uniformity of BCRA Color Tiles

The second series of Ceramic Color Standards (CCSII) were examined using the 6 degree hemispherical geometry. The color and uniformity for each of the 12 tiles in the series along with the Black and White compliment tiles were considered for this experiment. Another intent was to obtain data and offer suggestions on the reproducibility of Polytetrafluorethelene (PTFE) samples. The Varian Cary 5# (Cary 5D), and the Perkin-Elmer Lambda 19 (Lambda 19) were the instruments used to collect the data analyzed. Each instrument was used to take data using both the spectral included and the spectral excluded geometry.

Biographical Information:

Hometown: Charlevoix, MI

I just graduated form Miami University in Oxford, OH with a B.S. in Engineering Physics and a B.S. in Mathematics. I plan to return to Miami this fall to finish my M.S. in mathematics while finishing my eligibility as a pole-vaulter for the track team. As for future plans, I have none yet, we will see what develops after a year of grad school.

Mailing Address:

11550 Evergreen Lane
Charlevoix, MI 49720

Grant Number: 8T8019

Infrared Spectroscopic Imaging

Jeffrey Harbold
Rochester Institute of Technology
SURF Student, Optical Technology Division

Ted Heilweil
Advisor
Research Chemist, Optical Technology Division
NIST Physics Laboratory


ABSTRACT

Infrared spectroscopy is an established technique for chemical analysis. Combining a commercial Fourier transform infrared (FT-IR) spectrometer/microscope system modified for step-scan operation with an indium antimonide (InSb) focal-plane array (FPA), we have constructed an imaging system capable of simultaneously collecting sample images and spectra from 2-5.5 microns in both reflection and transmission modes. A brief introduction to the Fourier transform spectroscopic method and its integration into the imaging system will be discussed. Data analysis methods and the results of preliminary imaging trials will be presented in addition to applications of this technique.

Biographical Information:

Hometown: York, Pennsylvania

B.S. in physics earned May, 1998 from the Rochester Institute of Technology in Rochester, NY I will attend graduate school at Cornell University in the Applied Physics program beginning fall, 1998.

Grant Number: 8T8005

To Sonicate or Not to Sonicate: Dissolving the Ocean Floor in
Less than Three Hours

Melissa Bost
Appalachian State University
SURF Student, Ionizing Radiation Division

Ken Inn
Advisor
Research Chemist, Ionizing Radiation Division
NIST Physics Laboratory


ABSTRACT

In order to determine levels of radioactivity in soils and sediments, complete dissolution must be achieved. Current methods of dissolution by leaching with acids are caustic, expensive, time consuming, and intricate. In the search for an easier and "greener" method, the effects of ultrasonic dissolution were studied along with effects due to other confounding variables, such as mass of sample, temperature, and time.

Biographical Information:

I am currently a junior at Appalachian State University in Boone North Carolina. My major is Applied Physics with a concentration in Environmental Physics. I enjoy hiking and rock climbing. I am also engaged to be married on August 22!

Mailing Address:

Melissa Napier (my name will be changed as of August 22)
ASU Box 17366
Boone, NC 28608

Grant Number: 8T8008

Josephson Tunneling and Non-Destructive Imaging of the Bose Einstein Condensate

Jennifer Sebby
Creighton University
SURF Student, Atomic Physics Division

Steven Rolston
Advisor
Physicist, Atomic Physics Division
NIST Physics Laboratory


ABSTRACT

The Bose Einstein Condensate is a macroscopic population of the groundstate wave function of a system. This system is only realized at temperatures very close to absolute zero. Because of the BEC's strict temperature dependence, ordinary imaging methods, such as scattering light, destroy the condensate. An alternate non-destructive imaging method called phase contrast imaging will be discussed. In addition, a short discussion of the calculations of a Josephson-type current flowing between two BECs trapped in a double potential well will be included.

Biographical Information:

Next fall I will be a senior physics major at Creighton University in Omaha, Nebraska. After graduating I plan to attend graduate school. This is my second summer as a SURF student. Last summer I also did my research in the Laser Cooling Lab.

Mailing Address:

608 Kenefick Hall
Creighton University
Omaha, NE 68178

Grant Number: 8T8008

Photoassociative Spectroscopy of Laser-Cooled Atoms

Alicia Dwyer
Creighton University
SURF Student, Atomic Physics Division

Paul Lett
Advisor
Physicist, Atomic Physics Division
NIST Physics Laboratory


ABSTRACT

A result of atom cooling and trapping techniques has been the development of photoassociation spectroscopy of cold atoms. Photoassociation is the formation of an excited molecule that was induced by the absorption of light during a collision of two free atoms.

Because of these cold atoms whose kinetic energy spread is very small, this form of spectroscopy allows for high resolution of bound nuclear states near dissociation. We are able to study these molecular states to difficult to see with previous methods.

In order to get a more precise measurement of the energy between the ground state and the excited A state (vibrational level 165) of the sodium atom using photoassociation, it is necessary to first reference the A state to a well known energy difference in the atomic structure; primarily the separation between the P_1/2(F=2) state and the P_3/2(F=2) state. This allowed us to calibrate our system in order to measure the energy between the P_1/2(F=2) and the A state of sodium. This is part of a larger experiment to find the scattering length of sodium. How the calibration was accomplished and results of energy separations will be illustrated in this talk.

Biographical Information:

I am from Bartlett, Nebraska. I am going to be a senior physics major at Creighton University in Omaha, Nebraska. I plan to attend graduate school after graduation in either physics or engineering.

Mailing Address:

704 Kenefick Hall
Creighton University
Omaha, NE 68178

Grant Number: 8T8011

Laser Locking Techniques for Use in Laser Cooling and Trapping of Atoms

Kevin Koch
Truman State University
SURF Student, Atomic Physics Division

Carl Williams
Advisor
Physicist, Atomic Physics Division
NIST Physics Laboratory


ABSTRACT

In order to successfully cool and trap clouds of neutral atoms, the frequency stability of the lasers being used is of vital importance. The linewidth of the atomic transitions that need to be utilized is on the order of only 5 MHz. This limitation, as well as the mechanical instability and frequency roaming properties of the laser systems themselves requires the implementation of active feedback frequency control in order to lock the laser. I will discuss how this technique is performed using methods of saturated absorption spectroscopy, lock-in amplification, and external cavity laser frequency control.

Biographical Information:

Entering third year at Truman State University where I am majoring in physics. Hometown: Milwaukee, Wisconsin

Mailing Address:

734 Lost Woods Road
Oconomowoc, WI 53066

Grant Number: 8T8005

Computationally Efficient Formulas for Diffraction Effects

Matthew Terraciano
Appalachian State University
SURF Student, Optical Technology Division

Eric Shirley
Advisor
Physicist, Optical Technology Division
NIST Physics Laboratory


ABSTRACT

Radiometric measurements often involve collecting light that has been emitted by a source and transmitted through a series of baffles or apertures. Diffraction effects can often explain deviation of such measurements from what would be expected from geometrical optics. This talk will present revised formulas to estimate diffraction effects. They are found to be more computationally efficient than previous formulas.

Biographical Information:

I am a senior at Appalachian State University in Boone, NC. Next year I will attend a graduate school for physics. In May I will graduate from Appalachian State with a double major in physics and math. My hometown is Charlotte, NC, but I am originally from New Jersey.

Mailing Address:

314 Meadowtree Drive #220
Boone, NC 28607

Grant Number: 8T8004

Dynamic Mode-Matching into a Scanning Fabry-Perot Cavity

Jessica Ree
Bryn Mawr College
SURF Student, Atomic Physics Division

John Lawall
Advisor
Physicist, Atomic Physics Division
NIST Physics Laboratory


ABSTRACT

Scanning Fabry-Perot interferometry requires the input laser beam to match the mode of the cavity as the length of the cavity changes. We propose doing this with an a daptive optic consisting of two independent moveable lenses. We present calculations appropriate to the NIST Atomic Displacement Metrology project for a Fabry-Perot cavity with length scanning from 18 to 23 cm.

Biographical Information:

Jessica Ree is from southern California. This fall she will begin her senior year at Bryn Mawr College in Pennsylvania where she majors in physics and mathematics.

Mailing Address:

C-1468 Bryn Mawr College
101 N. Merion Avenue
Bryn Mawr, PA 19010-2899

Grant Number:

What are Optical Tweezers?

Juliette Selb
Ecole Sup. D'Optique
SURF Student, Atomic Physics Division

Kristian Helmerson
Advisor
Physicist, Atomic Physics Division
NIST Physics Laboratory


ABSTRACT

The optical tweezers are a three-dimensional trap consisting in a single laser beam tightly focused on an object. It is basically a balance between two optical forces: the gradient force and the scattering force resulting from the refraction and the reflection of light on the object.

The set-up at NIST contains two traps, one of them being mobile. This enables us to trap two different objects (cells, coated beads, for instance) and to make them collide.

Biographical Information:

I came from France, and study in Supoptique, an optics engineering school in Orsay (about 20 miles south of Paris). I will begin my third year in September, which is more or less equivalent to a senior year.

After Supoptique, I will have the choice between trying to find an engineer job or beginning a Ph.D., but I don't have any definite plans yet.

Mailing Address:

27, rue Hüneberg
67 270 Kienheim
France

Grant Number: 8T8022

Monte Carlo Simulation of Pulsed Laser Deposition

Kent Lambert
Jackson State University
SURF Student, Ceramics Division

Albert Paul
Advisor
Physicist, Ceramics Division
NIST Materials Science and Engineering Laboratory


ABSTRACT

The Direct Simulation Model is compared with the Continuum Model showing why Direct simulation was used. The results of the Direct Simulation Monte Carlo (DSMC) show the changes in dynamics. The Peak Mass vs. Velocity of the DSMC at different temperatures shows a discrepancy as compared with the experimental data gathered with a mass spectrometer suggesting a need to change parameters within the model. The results of the changing the gas pressure are shown.

Biographical Information:

Rising senior at Jackson State University, Jackson Mississippi.
Major: Theoretical Physics
Mississippi Redneck

Mailing Address:

P.O. Box 55554
Jackson, MS 39296

Grant Number: 8T8019

Numerical Simulation of Laser Scattering from Microrough Surfaces with Dielectric Overlays

Jeffrey Chabot
Rochester Institute of Technology
SURF Student, Optical Technology Division

Thomas Germer
Physicist, Optical Technology Division
NIST Physics Laboratory


ABSTRACT

While optical scattering from microrough surfaces is a well-studied phenomenon, the introduction of thin dielectric overlays with a correlated roughness introduces changes in the data that are not currently understood. We numerically modeled the system and several effects that could produce the experimental data. Results are discussed, as well as directions for future studies.

Biographical Information:

I'm originally from Manchester, NH. I'm entering my fifth year at RIT. In my free time I enjoy playing the bass and intramural football.

Mailing Address:

160 Colony Manor Drive
Rochester, NY 14623

Grant Number: 8T8007

Establishing a Scale of Directional-Hemispherical Reflectance

Johnny Seymore III
Bethune-Cookman College
SURF Student, Optical Technology Division

P. Yvonne Barnes
Advisor
Physical Scientist, Optical Technology Division
NIST Physics Laboratory


ABSTRACT

A modified Van den Akker auxiliary sphere method was used to establish the absolute diffuse directional-hemispherical (d/h) reflectance scale at NIST using 6º/h geometry. This method is now being used to investigate directional-hemispherical reflectance using 0º/h geometry. These preliminary investigations have resulted in an improvement in the previous methods and techniques. When completed, a 0º/h reflectometer will be used to transfer the absolute scale to other materials. A reflectometer measures the reflectance of an unknown sample relative to a diffuse reference standard such as Polytetrafluoroethylene (PTFE). The absolute reflectance factors of PTFE for 0º/h geometry will be determined using this method. The motivation for the previous intercomparison between national standardizing laboratories was to decrease the overall uncertainties associated with these measurements. Ideally, an uncertainty ±0.001 was desired for d/h reflectance factors. The impetus for the upcoming intercomparison is to determine the agreement between laboratory results.

Grant Number: 8T8008

Standardization of Radiopharmaceuticals

Gregory Kubicek
Creighton University
SURF Student, Ionizing Radiation Division

Brian Zimmerman
Research Chemist, Ionizing Radiation Division
NIST Physics Laboratory


ABSTRACT

Positron Emission Topography or PET scans are non-invasive techniques for medical diagnosis. Thirty thousand PET scans are performed annually in the U.S., 22,000 of which use a radio-tracer, a chemical that is at the basis of PET scans, known as 18F-fluodeoxyglucose (FDG). To ensure the continued safety and efficiency of nuclear medicine it becomes important to standardize the activity of radio-tracers such as FDG. Presented will be the data, analysis, and overview of the determination of a new standard for the radio-tracer FDG. Our measurements were based on a 15 mL sample of 18F supplied to us through the National Institutes of Health (NIH). Measurements were taken with both the capintec CRC-35R and CRC-12 dose calibrators. The activity of the 18F was determined using 4(( liquid scintillation counting along with the CIEMAT/NIST 3H-efficiency tracing. The measured activity for our sample of 18F was 2.9GBq/g. This activity corresponded to the following CRC-12 dial settings: for ampoule I a dial setting of 479(5, a 7.8 percent difference from the manufacturer's recommended setting; ampoule II 477(6, a 7.3 percent difference; plastic syringe 485(5 for an 8.8 percent difference; and the dose vial had a new dial setting of 465(5 which corresponds to a 4.9 percent difference from the previous dial setting. The uncertainties on our dial settings were all equal to or less than 1 percent. The percent differences in dial settings signify that currently hospitals overestimate the radiation given to patients, this constitutes a waste of product by the manufacturers of the radio-tracer and a possible threat to patients who are not receiving the radiation they were once believed to be.

Biographical Information:

Greg Kubicek's hometown is Willmar, Minnesota. He attends Creighton University and will be a junior next fall. Greg currently seeks a double major in psychology and health physics and plans on a career in medicine after graduation. Greg's hobbies include chess, fishing, and playing recreation-league sports.

Mailing Address:

3013 2nd Avenue, NW
Willmar, MN 56201

Grant Number: 8T8006

Monitoring the Motion of Optically Trapped Particles

Ariss DerHovanessian
Swarthmore College
SURF Student, Atomic Physics Division

Kristian Helmerson
Advisor
Physicist, Atomic Physics Division
NIST Physics Laboratory


ABSTRACT

For years optical tweezers have been used to trap and manipulate microscopic objects. Several experiments have applied dual-beam optical tweezers toward the study of microscopic adhesion. Unfortunately, one of the major limitations of such studies has been the inability to obtain precise quantitative information about the motion of trapped particles. I will present an approach to position detection based on differential interference contrast (DIC) microscopy, which overcomes this limitation. This method has advantages in a number of applications beyond studies of biological and chemical adhesion, most notably the ability to measure piconewton forces acting upon trapped objects. Furthermore, while results are still preliminary, we have used this method to examine the adhesion of a well-studied antigen-antibody system, modeled by dinitrophenol-coated silica beads and beads coated with the anti-dinitrophenol IgE clone SPE-7. These experiments suggest a characteristic time of adhesion on the order of 1 second for this system.

Biographical Information:

I am a junior at Swarthmore College, majoring in Chemistry and Physics. While my future remains uncertain, I am interested in pursuing a career in biophysics-related research.

Grant Number: 8T8007

Pulsed Plasma Measurements in an Inductively Coupled Plasma (ICP) Source

Victoria C. Beckles
Bethune-Cookman College
SURF Student, Atomic Physics Division

Eric C. Benck
Advisor
Physicist, Atomic Physics Division
NIST Physics Laboratory


ABSTRACT

Pulsed plasma discharges are being studied as a means to significantly improve etching quality used in the manufacturing of semiconductor products. Pulsing power to a plasma alters the electron density, the electron temperature, and the negative ion density of the plasma. Measurements were performed for radio frequency (rf) powers between 100W and 350W at 13.56 MHz in an inductively coupled plasma source. Time resolved electrical and optical emission measurements were used to study the changes in the plasma for different rf on and off times. The plasma can exist in two different modes, a capacitively coupled discharge mode or an inductively coupled discharge mode, depending on the pulse periods. The gases used to produce the plasma act differently under similar conditions, such as the same power, pressure, and period. Pure Argon and Argon-Oxygen gas mixtures were used in these measurements. Temporal and spatial plasma distributions were monitored with an ICCD camera.

Grant Number: 8T8010

High Temperature Cell Design for Characterizing Flame Extinguishing Agents

Jennifer Jakubowski
Union College
SURF Student, Optical Technology Division

Gerald Fraser
Advisor
Research Chemist, Optical Technology Division
NIST Physics Laboratory


ABSTRACT

I worked on part of a three-year project developed by the Advanced Fire Measurements Group in the Building and Fire Research Laboratory and the Army Research Laboratory. The goal of the entire project is to develop an instrument for characterizing flame extinguishing agents with fast enough response times (about 10 ms) to measure the performance of the various agents in real-scale fires. I was responsible for the design of the high temperature cell that is used to heat flame-extinguishing agent samples, simulating the conditions of an actual fire. When heating a cell to high temperatures of at least 1000 K, there were several factors that had to be considered in order to optimize the performance of the cell. Several temperature measurements were made in order to determine the optical dimensions and materials for the cell at the high temperatures. After these measurements, I was able to finalize the cell design and construct the actual cell.

Biographical Information:

My hometown is Saratoga Springs, NY. I am a chemistry major entering my junior year in the fall at Union College, Schenectady, NY. I will most likely go to graduate school to do research after I graduate from Union.

Mailing Address:

Reamer Campus Center-Box #1009
Union College
Schenectady, NY 12308

Grant Number: 8T8018

Characterization of the Constituents for Hybrid Composites

Shahrooz Zaghi
University of California-Irvine
SURF Student, Polymers Division

Donald Hunston
Advisor
Physical Scientist, Polymers Division
NIST Materials Science and Engineering Laboratory


ABSTRACT

Hybrid composites are materials of extraordinary capabilities. They are basically fiber-reinforced polymers and weigh much less than a metal with the same strength and/or stiffness. In addition, hybrids are relatively easy to shape or mold. Hybrids composed of both glass and carbon fibers are of particular interest. In order to understand better the physical behavior of a hybrid, information about the mechanical properties of each constituent of a hybrid is needed. We investigated the tensile strength of single carbon and glass fibers. The data suggested that fiber strength behaves as we had expected. Furthermore, we concluded that the Weibull equation is a good model for the behavior of a single glass or carbon fiber.

Biographical Information:

Shahrooz currently attends the University of California at Irvine where he will hopefully be finishing up the chemistry curriculum next year. He enjoys performing lab work, as long as he's getting good results. When free from schoolwork, he gets involved in classical music and outdoor sports. Attending NIST in his opinion is one of the best things that have ever happened to him. He is looking forward to doing graduate work in materials science, and then looking for a job.

Mailing Address:

6218 Platt Avenue
Woodland Hills, CA 91367

Grant Number: 8T8013

Data Acquisition and Control of a Gas Flow Measurement System Using LabVIEW

Lisandra Ortiz-Cruz
University of Puerto Rico-Humacao
SURF Student, Metallurgy Division

Stephen Ridder
Advisor
Metallurgist, Metallurgy Division
NIST Materials Science and Engineering Laboratory


ABSTRACT

The LabVIEW( graphical programming language was used to create a Data Acquisition and Control (DAC) application for running an experimental gas flow facility. This facility, in the Metallurgy Division of NIST's MSEL, is used to evaluate the geometric design and operating parameters of gas jet assemblies used for the atomization of molten metal streams. The testing procedure involves several sequential operations including the control of process pressure, actuation of the gas flow valve, measurement of pressure and temperature data, and saving the data in a digital format. The graphical interface developed for this project allows these experiments to be setup and run efficiently and produces data files that are easily transportable to other computer applications and platforms. The design and operation of the LabVIEW code will be discussed and results of gas flow experiments will be shown.

Biographical Information:

My name is Lisandra Ortiz-Cruz. I'm 20 years old. My hometown is Humacao, Puerto Rico. I am a third year physics and electronics major at the University of Puerto Rico, Humacao campus. I will apply to graduate school in electronics engineering when I finish my major.

Mailing Address:

HC-02 Box 11629
Humacao, PR 00791-9618