Kiosk 2

Many spectroscopic observations in astrophysics, planetary science, heliophysics, and earth science benefit from spatial mapping of some sort. In most cases, this requires slit-stepping a conventional long slit spectrograph or the use of a multi-object or integral-field spectrograph. The relatively low reflectivity of UV mirrors and poor transmission of most dielectrics severely restrict the design space of UV multi-object and integral field spectrographs (MOS and IFS, respectively). Over the last decade, the LASP astrophysics group developed several research programs exploring all of the practically feasible approaches to perform UV spectroscopic multiplexing in space. In this talk, I’ll review some of the scientific drivers for improved multiplexed spectroscopy and the technologies we’ve developed to perform such observations. I’ll conclude with an overview of missions and instruments that we are developing, which will perform state of the art observations in the 2030’s and 2040’s.

String theory offers a viable theory of quantum gravity, with spin 2 gravitons encoded in closed strings.  But the failure to find evidence for supersymmetry at the LHC has left string theory in an uncertain state.  A solution to the problem is in plain sight: revert to classic nonsupersymmetric, bosonic string theory, reenvisaged as a theory of all the forces, not just the strong force.  The classic theory correctly reproduces the Brauer-Weyl (1935) algebraic relation between fermions and bosons seen in the standard model, whereas supersymmetry does not.
Sages rejected the classic theory on the grounds that (1) it does not admit fermions, and (2) its ground state is tachyonic.  But rejection (1) assumes that fermions are strings, wheres the fermions of bosonic string theory are the endpoints of strings, and are not themselves strings; in modern parlance, the fermions are excitations of the D-brane boundary of strings.  As to rejection (2), the properties of the tachyon are precisely those of a Higgs field: it is a multiplet of the unbroken symmetry; the "vacuum" state where the Higgs field vanishes identically is tachyonically unstable; and it has spin zero.  The gauge group of bosonic string theory is tightly constrained.  I show that a 26-dimensional bosonic string theory that fits the standard model emerges without contrivance.  Unburdened by supersymmetry, bosonic string theory has the potential to bring string theory back into the realm of testable physics accessible to present-day observation and experiment.

This is the inaugural W. Carl Lineberger Seminar which is designed to advance graduate student-organized seminars within the Physical Chemistry Program of the Department of Chemistry at the University of Colorado Boulder. The seminars address current topics in physical chemistry, promote rigorous scholarly discussion, and foster collaboration among graduate students, faculty, and invited speakers. This seminar program is supported by private donations to the University of Colorado Foundation.

The dynamics of photoexcited solute molecules and the properties of liquid interfaces are studied by carrying out spectroscopy and scattering experiments on flat liquid water jets. In one set of experiments, solute dynamics are probed using time-resolved photoelectron spectroscopy in which molecules are photoexcited with a femtosecond UV pulse and photoionized with a time-delayed femtosecond XUV pulse (at 21.7 eV). The time-dependent photoelectron spectra provide a unique probe of the relaxation of photoexcited neutral and anionic species in aqueous solution. Results will be presented for several negative ions including phenolate,  bromophenolate, and nitrophenolate. These experiments probe the competition among the various relaxation pathways including internal conversion, dissociation, and electron ejection.

In complementary experiments, the liquid interface is explored in molecular beam scattering experiments from flat liquid jets of cold salty water (-50 °C, 8 m LiBr). In contrast to cylindrical jets, flat jets provide a large target area and well-defined surface normal, both of which are highly advantageous for scattering experiments. Product angular and translational energy distributions are measured for rare gas and molecular scatterers. The competition between impulsive scattering (IS) and thermal desorption is measured, and the energy loss in the IS channel is characterized using a soft-sphere model. Results are sensitive to both the scatterer identity and its collision energy.  

I will discuss NASA's Lucy mission, which is the first reconnaissance of the Jupiter Trojan asteroids. Asteroids are the leftovers from the age of planet formation. But, unlike the planets themselves, they have remained relatively unchanged since they formed. As a result, they hold vital clues to how our Solar System formed and evolved, and thus can be considered the fossils of planet formation. Lucy will visit eight of these important objects between 2027 and 2033. It will use a suite of remote sensing instruments to map geologic, surface color and composition, thermal and other physical properties of its targets at close range. Lucy, like the human fossil for which it is named, will revolutionize the understanding of our origins.

TBA

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.

I will discuss NASA's Lucy mission, which is the first reconnaissance of the Jupiter Trojan asteroids. Asteroids are the leftovers from the age of planet formation. But, unlike the planets themselves, they have remained relatively unchanged since they formed. As a result, they hold vital clues to how our Solar System formed and evolved, and thus can be considered the fossils of planet formation. Lucy will visit eight of these important objects between 2027 and 2033. It will use a suite of remote sensing instruments to map geologic, surface color and composition, thermal and other physical properties of its targets at close range. Lucy, like the human fossil for which it is named, will revolutionize the understanding of our origins.

TBA

Join CU Wizards Professors Eleanor Hodby and Steven Pollock, along with Gwen Eccles, as they dive into the fascinating world of light, color and color perception - where physics and biology meet!

Mineralogy as a discipline has established the principles of crystal structure, symmetry, and chemistry that dictate all of modern material science underlying everything from computers to photonic technologies operating based on quantum mechanical principles. However, nature itself also acts a laboratory assembling naturally occurring minerals that exhibit even exotic quantum phenomena. I will discuss examples such as natural superconductors, strange metals, or spin liquids which result from the interplay of the quantized nature of electrons, spin, and lattice. I will conclude with a general perspective on how nature inspires and teaches us about intriguing physical phenomena that surround us, often in plain sight

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.

Almost exactly 100 years ago, in the early months of 1926, Erwin Schrödinger published a series of four papers that would transform not only the prevailing theories of physics but also mankind’s very understanding of the nature of reality.  Though his work indisputably built upon the ideas of countless others, these papers crystalized the central and most astounding claim of what has become modern quantum mechanics: that at its heart, nature can be understood not as a collection of particles interacting in space but as the endless oscillation of an unseen “wavefunction,” which silently tallies and updates the probabilities of future events. In this talk, we will discuss the historical backdrop of these four transformative papers and then unpack the mathematical and physical innovations they contain (no background knowledge of math or physics is assumed). Finally; we will trace their centennial trajectories through the ensuing years, to reveal the enduring importance of these timeless papers, whose insights—and mysteries—have both only deepened with age. 

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.