The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

While electron microscopy enables imaging of individual atoms, the sample thickness is typically limited to a few hundred nanometers. Although super-resolution optical microscopy permits high-resolution visualization of subcellular structures, it requires staining of the sample. In contrast, EUV and X-ray microscopy allow imaging of entire biological cells and other thick specimens with spatial resolutions down to ~10 nm.
In recent years, a new class of laser-driven, coherent EUV and soft X-ray sources based on high harmonic generation has been developed. These sources now make it possible to perform high-resolution coherent imaging experiments on a laboratory scale, which were previously restricted to large research facilities such as synchrotrons. In this talk, we will demonstrate high-resolution quantitative microscopy using EUV ptychography on a laboratory scale. We will also discuss how elemental composition can be extracted from these images, as illustrated with microbiological model organisms such as Aspergillus nidulans and Escherichia coli. Additionally, first results of imaging with higher photon energies in the soft X-ray spectral range will be presented, paving the way for future studies of intact biological samples in a near-native state at resolutions below 50 nm.

All chemical reactions are controlled by species we rarely detect: short-lived carbenes, radicals, and ketenes steer reaction pathways and ultimately determine selectivity and yield. Conventional tools such as GC/MS or NMR usually miss intermediates, even though mechanistic insight is urgently needed for rational process optimization.
In this seminar, I introduce operando Photoelectron Photoion Coincidence (PEPICO) spectroscopy with vacuum ultraviolet (VUV) synchrotron radiation at the Swiss Light Source as a multiplexed approach to reaction analysis. By detecting both ions and electrons after VUV ionization, PEPICO connects mass spectrometry with isomer-selective photoelectron fingerprints, allowing us to disentangle complex reaction mixtures.
I will illustrate how this approach changes our mechanistic understanding in heterogeneous catalysis and high-temperature chemistry, including zeolite-catalyzed plastic pyrolysis, where we identify mechanistic routes to benzene, toluene, and xylenes. Moreover, we turn to biomass conversion, where transient ketenes are the unwelcome guests that steer selectivity off-target.
I will leave you with a practical sense of what intermediates we can observe, how spectra are interpreted, and where operando detection can unveil new mechanistic insights.

The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.