2023 Science Undergraduate Laboratory Internship (SULI) Program Participants & Projects

Student: Joshua Balbach

Mentor: Amy Cordones-Hahn

Project Title: The Mystery of the Traveling Electron General Audience Abstract

Project description: With global temperatures on the rise, we need to look for new sources of energy that will be sustainable for the future. Hydrogen fuel has potential as a clean fuel source, but much work is needed to optimize its production. One area requiring investigation is how electrons travel within a molecular catalyst. At SLAC, the free electron laser at LCLS allows for time resolved x-ray absorption spectroscopy measurements (XAS). Time-resolved XAS will let us track how two electrons travel within our catalyst. We have studied how the first electron travels in our catalyst, but we have not been able to track the second electron. To see where the second electron travels, we must first prepare a catalyst with the first electron already excited. In this experiment, we perform electrolysis to put one electron onto the bridge of our catalyst and use UV-vis spectroscopy to measure its stability. After reduction, we see a peak around 600 nm appear and stay constant for an hour before broadening, remaining stable for another hour, and then decaying. We suspect the decay in spectrum signal is due to deprotonation of the bridge, since the only experiment we performed and obtained similar results was when we used wet acetonitrile. Over the course of these experiments, I learned a lot of electrochemistry, such as the importance of using an actual reference electrode over a pseudo-reference electrode. On our second electrolysis experiment, the results I got were wildly different from the first experiment because we used a pseudo-reference electrode. I also learned over the course of these experiments how to plan an experiment, including confirming we have all necessary materials. My project this summer has also helped me improve my communication skills with members of my lab to ask for assistance and to coordinate experiments using limited resources.

Student: Jason Curcio

Mentor: Emilio Nanni

Project title: Implementation of makefile compilation for ACE3P simulation software 

Project description: ACE3P is a collection of conformal, higher-order, parallel finite-element electromagnetic C/C++ codes implemented on massively parallel computers for increased memory and speed. For this project, the following goals were implemented on Perlmutter within The National Energy Research Scientific Computing Center (NERSC). First, introduce a user-friendly workflow utilizing Visual Studio Code (VS Code) for remote SSH access to NERSC. Second, integrate the VS Code workflow with Git Version Control, documenting the use of GUI elements and cloned repositories. Third, Optimize ACE3P compilation by modernizing outdated Makefiles to align with current versions. Lastly, identify which resources are deprecated and adapt the Makefiles to the architecture of Perlmutter. Makefiles are essentially instruction files for code compilation, and we used autoconf to implement high level configuration scripts and templating. These scripts are essential because this software suite is used on multiple supercomputer platforms, and there must be top-down support for changing file and library paths. ACE3P currently uses Boost to compile, which has waning usage and outdated documentation. Scientists from other national laboratories are discouraged from using the code because it’s difficult to add or subtract from the repository without knowing how to adjust compilation accordingly. Together, these goals are meant to increase the portability of ACE3P code and collaboration among the scientific community across laboratories. Additionally, SLAC software engineers will be able to interface more efficiently with the ACE3P repository using Visual Studio Code. I created documentation for each of these processes informing new and existing users of my workflow. This documentation included common issues I experienced during the project, and what I did to resolve them. Overall, I became much more aware of how software development takes place in a research environment, and how to be a useful individual contributor. My communication skills were strengthened both when talking with my mentors and when writing technical documentation.

Student: Jessica Flowers

Mentor: Robert Schoenlein

Project title: Julia-Based Global Analysis Routine For Time-Resolved Spectroscopy

Project description: Time-resolved spectroscopy plays a pivotal role in exploring the photochemical response of a molecular system, as it is designed to measure time-dependent signals. With the aid of ultrafast laser pulses, we have the ability to trace a system’s behavior in the wake of a photoexcitation. This approach grants us profound insights into the intricate dynamics of these systems and teaches us of their behavior. At the intersection of chemistry, physics, and biology, time-resolved spectroscopy finds widespread applications. Experiments of this kind produce incredibly vast amounts of data, necessitating the development of a model-based analysis routine. Models serve as powerful mathematical tools that allow us to approximate the complicated physical realities in a more manageable and comprehensible manner. By employing models, researchers can extract meaningful insights from the data, even when the underlying physical processes are too intricate to be directly understood in their original form. Two such models are the kinetic and spectral models, which describe the time-dependent evolution of a material and a material’s emissivity as a function of wavelength, respectively.  Researchers wish to describe their time-resolved experiments in terms of these two models, the process of which is termed “global analysis”. With larger data sets, the implementation of global analysis becomes complex, and there exists no general approach. Thus, researchers in the past have been been required to develop extremely experiment-specific programs to analyze their data. The primary goal of my internship has been to help develop a simple, and broadly applicable Julia-based global analysis routine designed to streamline the analysis of complex spectroscopic data. We aim to create a user-friendly interface that allows for the specification of custom models while requiring minimal code changes between new implementations.

Student: Veronica Show

Mentor: Ben Ofori-Okai

Project Title: Developing a THz Frequency Humidity Probe: Simulating Spectra

Project Description: This project plans to develop a terahertz probe capable of remote measurements of humidity in potentially dangerous environments. One application of this probe could be using it to predict the locations of wildfires. Previous laboratory data showed significant changes in the transmission spectrum between different humidities. Terahertz radiation lies in a unique location in the electromagnetic spectrum in between microwave and infrared radiation; it is ideal for measuring the vibrations and rotations of small molecules, such as water. Using a computational chemistry program, NWChem, we investigated both classical and quantum mechanical contributions to the terahertz absorption of water vapor. NWChem was used to optimize geometry and calculate moments of inertia. Direct calculation of vibrational modes using NWChem yielded intermolecular vibrations, which were at too of a high frequency to agree with experimental data. To consider rotational contributions, we used a more classical approach invoking the rigid rotor model, which assumes fixed bond length and rotation around the center of mass. Applying this model, transition energies were calculated from the moments of inertia and used in a finite difference time domain simulation, which discretizes Maxwell’s equations.