Department of Physics and Astronomy, San Francisco State University

San Francisco State University
Physics & Astronomy Colloquium Series
Monday, May 11, 2026
SEIC 210, 3:30 PM

Speaker: Prof. Xiangdong Zhu (UC Davis)

Let There Be light - Materials studies using linear optics that exploits various symmetries

When light is incident on a solid material, its electromagnetic fields drive electrons in the material so that the charge density changes accordingly. Those changes that vary linearly with the fields are linear optical responses. The re-radiation from these responses can be used to characterize the solid material in question. Most linear optical responses only cause small perturbations to light reflection and transmission, yet they reveal most interesting properties of the material. I will show how effects from these perturbative linear responses on optical reflection can be obtained using a simple perturbation treatment. And by taking advantage of symmetry properties that distinguish one material from another or one phase of a material from another phase of the same material, we can learn a great deal about materials using linear optical techniques.

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San Francisco State University
Physics & Astronomy Colloquium Series
Monday, May 4, 2026
SEIC 210, 3:30 PM

Speaker: Dr. Junze Zhou (Lawrence Berkeley National Lab)

"Nanoimprinted Scanning Probe for Enhanced Spectroscopies and Nanoimaging on 2D Excitons and Plexcitons"

Optically active scanning probes simultaneously measure nanoscale topography and optical spectra with sub-diffraction spatial resolution. This capability is critical for elucidating how both intrinsic material properties and artificially engineered structures influence macroscopic functionality in low dimensional systems. In this talk, I will introduce a novel scanning probe fabricated using a cost-effective and scalable nanoimprinting approach, enabling correlated spatial, spectral, and temporal measurements in a single platform. I will then discuss how the nanoimprinted probe, together with tailored plasmonic cavities, enhances the optical response of 2D excitons in atomically thin materials, enabling probing dark excitons, strain-localized states, and the strong exciton-cavity interaction underlying plexciton formation.

San Francisco State University
Physics & Astronomy Colloquium Series
Monday, April 20, 2026
SEIC 210, 3:30 PM

Speaker: Maureen Savage (UCSC Observatories)

"Science Instrument and Observatory Development - A perspective"

Perspectives on observatory and instrument development including work at San Francisco State University, NASA Ames Research Center, and UC Santa Cruz. Discussion of current existing and future projects to enhance observatory operations, as well as how SFSU physics and astronomy disciplines can enable support for critical emerging technologies in fusion power and space weather. I will include some details regarding the Stratospheric Observatory For Infrared Astronomy (SOFIA), Thirty Meter Telescope (TMT), and UC Santa Cruz current projects for Keck (SCALES, the Keck Adaptive Secondary). I also hope to include information on the International Thermonuclear Experiment Reactor (ITER) and a planned Space weather (small sat) project.

San Francisco State University
Physics & Astronomy Colloquium Series
Monday, April 13, 2026
SEIC 210, 3:30 PM

Speaker: Dr. Anne Metevier (Lick Observatory/UCSC)

"Expanding Education Programs through Lick Observatory and UC Observatories"

Lick Observatory is home to a suite of historic telescopes and active research telescopes atop Mount Hamilton near San Jose. The University of California Observatories stewards Lick Observatory and is significantly expanding Lick's education programs, particularly at the college level, thanks to a generous grant from the Gordon and Betty Moore Foundation. Goals of this expansion include broadening access to the observatory through impactful educational experiences that provide exposure to research processes and, in some cases, to observatory careers. Lick's college-level programs are run through a new consortium of Bay Area community colleges and Cal State campuses that collaborate with Lick, called the ASTRAL Consortium. Anne Metevier will describe ASTRAL's programs, including ways that students and faculty at San Francisco State can get involved. She will describe the astronomy and education research-based underpinnings for the programs, how the programs have been designed to engage both STEM and non-STEM students, and how professional development training for graduate students and postdocs is woven into the instruction of some of the programs, providing near-peer interactions.

San Francisco State University
Physics & Astronomy Colloquium Series
Monday, April 6, 2026
SEIC 210, 3:30 PM

"The Ghosts of Stars: The Heaviest Elements Found in Nature and Where They Are Born"

Erin Huntzinger, PhD Candidate, UC Davis

Over its 14-billion-year history, the composition of the universe evolved in chemical complexity, starting with hydrogen and over time forming nearly all elements on the periodic table. Elements heavier than iron are produced by neutron capture processes, namely the slow neutron capture process (s- process) and the rapid neutron capture process (r-process). The heaviest elements produced in nature, radioactive actinides such as thorium and uranium, are formed solely by the r-process. While the s-process is known to occur in stars on the asymptotic giant branch, the astrophysical sites of the r-process remain uncertain. So far, neutron star mergers (NSMs) are the only confirmed sites for the r-process, but it is not yet known whether or not NSMs can fully account for the abundance of r-process elements we observe in the Milky Way. Are NSMs the dominant site of r-process production? Where else can the r-process occur? One way we can begin to answer this question is by investigating heavy element abundances derived from stellar observations. In this talk, I will discuss how we use these abundances to trace the production of r-process elements in the Galaxy over time, along with the challenges it presents in different populations of stars.

San Francisco State University
Physics & Astronomy Colloquium Series
Monday, March 30, 2026
SEIC 210, 3:30 PM

Prof. Luan Ghezzi (Volongo Observatory - UFRJ)

"The connections between the chemical abundances of stars and their exoplanetary systems"

Abstract: The stellar metallicity influences the occurrence of giant and small hot exoplanets. However, the role of elements other than iron on planetary formation is still unclear. In this talk, I will discuss the relations between the abundances of 13 chemical elements (Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, and Cu) for a sample of 561 Kepler exoplanet-hosting stars and the radii and orbital periods of their planets. These possible connections are investigated through comparisons between stars that host different planetary systems. I will also discuss the role of alpha elements in the formation of giant planets and examine the depletion of refractory elements in the Sun. The analysis of 25 solar twins in our sample suggests that this chemical peculiarity might be caused by processes other than planetary formation.