Past Events

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.

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.

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).

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.

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.

We show that targeted energy input from an electron beam in a transmission electron microscope (TEM), often combined with concurrent heating in a MEMS holder, drives atomic defect formation and phase transitions across four classes of low-dimensional materials: (1) few-layer transition metal phosphorus trichalcogenides (TMPTs), (2) graphene sandwich structures encapsulating either lithium droplets (2a) or a benzenehexathiol-based two-dimensional conjugated metal-organic framework (2b), (3) platinum nanocrystals on graphene, and (4) noble metals confined within carbon nanotubes.

Solar and stellar flares are explosive phenomena in which magnetic energy stored around starspots is suddenly released through magnetic reconnection. The radiation emitted during flares covers a broad range of wavelengths from radio to X-rays, each tracing different aspects of the flare process. In X-rays, the emission arises from hot thermal plasma heated by nonthermal electrons that travel upward from the chromosphere into the corona.

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.

From planting crops to making trains run efficiently, clocks have been an important tool throughout most of human history. Atomic clocks, based on quantum-mechanically-defined transitions in atoms, are currently the most accurate realizations of the second and underlie important technologies such as the global positioning system (GPS) and high-speed communications. This lecture will describe how atomic clocks work and their history, with a focus on compact clocks and the applications in which they are used.

CU Professors Kelvin Bates and Steven Brown travel the world to study the amazing, invisible, ethereal stuff that blankets our amazing planet and makes life on Earth possible.

Have you wondered...Why is the Sky Blue!? Why are sunrises orange? What is air made of exactly? How can you make your own cloud? Did you know the Earth wears sunglasses!? And what's the story about the greenhouse gases and what do they do?

This show will bring air down to Earth! It's geared for young students who are eager to learn about the science of our atmosphere.

Linear spectroscopy is used to learn about transitions from the ground states of systems. Nonlinear spectroscopies, such as transient absorption (TA) spectroscopy, first excite the system and then probe after some time delay, giving dynamical information about excited states and spectral information about their excitations. If the pump pulses are strong enough, then some molecules are excited multiple times, and the signal has contributions from singly excited molecules mixed with those from multiply excited molecules.

NASA science missions are often complex systems of systems, involving various stakeholders, including the United States’ Congress. To ensure a clear and concise communication of expectations, requirements, and constraints, NASA has adopted the Science Traceability Matrix (STM). STM provides a logical flow from the decadal survey to science goals and objectives, mission and instrument requirements, and data products. STM serves as a summary of what science will be achieved and how it will be achieved, with a clear definition of what mission success will look like.

Atomic electron tomography (AET) enables the determination of 3D atomic structures by acquiring a sequence of 2D TEM projection measurements of a particle and then computationally solving for its underlying 3D representation. AET is a challenging and labor-intensive experiment! In this talk, we offer two computational methods to alleviate these challenges and make the reconstruction procedure more robust.

Abstract: A new zoo consisting of dozens of heavy subatomic particles that contain more than three quarks and antiquarks have been discovered beginning in 2003.  Although they must be described by the fundamental quantum field theory QCD, the pattern of these exotic heavy hadrons remained unexplained for more than 20 years.  I will present a simple proposal for the pattern based on the Born-Oppenheimer approximation for QCD.  There are simple calculations in lattice QCD that would corroborate the pattern.

A surprising discovery has been compact systems of Earth to super- Earth-sized planets. While compact systems are common, their origin is debated. A prevalent assumption is that compact systems formed after the infall of gas and solids to the circumstellar disk ended. However, observational evidence suggests accretion may commence earlier. We propose that compact systems are surviving remnants of planet accretion during the end stages of infall.

The quantum 2.0 revolution is well underway, with a tantalizing future just over the horizon wherein computing, networking, sensing, and even time-keeping will be unimaginably more capable than they are today. The promise of this future hinges on the ability to control, entangle, and measure both individual qubits and large systems of them. Many of the most promising physical qubit systems being developed for these purposes are atomic in nature, i.e. trapped neutral atoms, trapped ions, and artificial atoms in crystals.

Abstract: In recent years, neutral atom tweezer arrays have emerged as a promising platform for quantum computing. Among various atomic species, alkaline-earth(-like) atoms—particularly ytterbium—offer unique advantages arising from their rich internal structure. In this talk, I will present progress from my PhD work, demonstrating how these features can be harnessed to build a useful quantum computer in the future.

The year 2024 was a breakthrough year towards the development of a nuclear optical clock, with three experiments reporting success in the laser spectroscopy of the lowest nuclear excited state of 229-Th. The highest accuracy was achieved at JILA via direct frequency comb spectroscopy of this, previously elusive, nuclear state. This success is the result of several decades of effort to precisely determine the transition energy and a first step towards nuclear precision spectroscopy and the development of a nuclear frequency standard of extremely high accuracy.

Engineering heterogenous multicellular tissue with native complexity remains one of the holy grails of regenerative medicine and basic biological research. As success in this regard would yield powerful bioengineered constructs useful in functional transplantation, high-throughput drug screening, and fundamental biology investigation, research efforts in our lab have centered around developing and implementing tools to spatiotemporally customize living cell function both from the “outside–in” and from the “inside–out”.