The first research project I worked on was under Dr. Melora Larson for a summer REU at the Jet Propulsion Laboratory (JPL) in Pasadena, California.  The overall goal was to test Renormalization Group (RG) theory by probing the ³He-⁴He tricritical point, but to do so more rigorously than in the 70s, increasing sensitivity via use of a SQUID.  My specific duty was to select the atomic percent concentration of manganese in a PdMn sensing cell that would maximize thermometer resolution.  Despite multiple attempts at taking data, an uncooperative SQUID controller and pesky heat leaks would only allow collection of data sufficiently higher than T_c to render a determination of thermometer resolution (half-width) impossible.

My experience continued upon my return to the UW, where I continued research with Prof. Oscar Vilches, studying adsorption of xenon on carbon nanotube bundles.  The project sought to understand what phases xenon takes once on the surface and if there are any phase transitions.  To shed light on these questions, I recorded (via LabVIEW) adsorption isotherms and calorimetry data, while becoming familiar with the vacuum system.  Our inquiries suggest melting in the second adsorbed layer at around 100 K.  However, these results gained limited credence as the xenon heat capacity signal amounted to a minor fraction of the overall signal.

My final condensed matter physics focus as an undergraduate was guided by Profs. Sam Fain and Marjorie Olmstead and relied on the use of scanning probe microscopy to study nanometer scale features on surfaces, particularly GaSe on As terminated Si.  The measurements were taken under UHV conditions, a feature which alone introduced me to a whole new world of equipment and procedures.  I prepared tungsten STM tips by etching, prepared silicon samples, worked on sample deposition and As termination, checked crystal structure with LEED, and have scanned samples with both STM and AFM techniques.  My main goal was to quantify the differences between AFM and STM scanning techniques for clusters less than 5 nm tall.  We believe that because tunneling current (the basis of STM measurement) is exponentially sensitive to surface height, whereas the Van der Waals force (the basis of AFM measurement) scales inversely with the sixth power, STM will reveal smaller, finer detail than AFM.  With the few data sets we were able to take, this proposition met mixed success.

Society of Physics Students (SPS)