Abstract: Modeling gas-phase chemical kinetics relevant to combustion and atmospheric chemistry requires a complete description of elementary reactions involving ephemeral species such as hydroperoxyalkyl radicals, Q̇OOH, which undergo competing sets of unimolecular reactions and bimolecular reactions with O2. The balance of flux from the competition affects rates of chain-branching and inherently depends on temperature, pressure, and oxygen concentration. Accordingly, the influence of [O2] on species formed via reactions of O2 with carbon-centered radicals (Ṙ), and the subsequent fate of Q̇OOH and related products, is central to developing accurate chemical kinetics mechanisms. However, reactions consuming intermediates from Ṙ + O2 are often simplified to such a degree that mechanism truncation error (uncertainty derived from incomplete reaction networks) becomes significant and precludes high-fidelity simulations of chemical systems for sustainable transportation energy.

Intermediates produced from Ṙ + O2 reactions of hydrocarbons and biofuels include cyclic ethers and alkene isomers, which are shown to undergo two unique types of reactions that are neglected in current gas-phase combustion models: (1) non-Boltzmann reactions, wherein rovibrationally excited radicals produced during H-abstraction undergo prompt ring-opening prior to collisional stabilization, and (2) stereochemical-dependent reaction pathways originating in closed-shell cyclic ethers that follow from the preceding ring-closing transition state [Q̇OOH]≠ and from subsequent cyclic ether peroxy radicals, both of which can facilitate new reaction channels including chain-branching pathways.

To ameliorate predictive deficiencies, results from a coupled experimental-computational workflow are outlined wherein sub-mechanisms, informed by speciation experiments, are developed and utilized as input into AutoMech, an open-source code for quantum chemical mechanism development. AutoMech is employed to calculate ab initio thermochemical and rate coefficeints for all species and reaction pathways in an initial mechanism. Elementary reactions are translated by AutoMech from 2D descriptions into stereochemically-enumerated representations. Potential energy surfaces are calculated using explicitly-correlated coupled-cluster energies with dispersion-corrected double-hybrid density functional theory geometries and frequencies. Master equation theory is used to calculate pressure- and temperature-dependent rate coefficients and partition functions for each reaction and species including for non-Boltzmann reactions. Results discussed include ongoing projects on species derived from cyclopentyl radicals and alkyl-substituted cyclic ethers produced from pentyl radical isomers. 

Join us on Saturday, November 15, 2025, for an electrifying experience as CU Physics Professor Daniel Bolton uncovers the wonders of electric charges and magnets up close! Ever wondered how electrical attraction and repulsion function or what transpires inside an electric circuit? Curious about the inner workings of a power plant in generating electricity? 

Discover the answers to these questions and more at CU Wizards' captivating science demonstrations. For over 40 years, CU Wizards has been delighting audiences with free public family shows each month at CU Boulder. Everyone is welcome to attend these engaging and enlightening events. 

Don't miss out on this "electric" atmosphere of discovery! 

The behavior of the doped Hubbard model at low temperatures is a central problem in modern condensed matter physics, with relevance to correlated materials such as cuprate superconductors. Despite extensive computational studies, many open questions remain on its low-temperature phase diagram, motivating its study through quantum simulation with ultracold fermionic atoms in optical lattices. Here, leveraging a recent several-fold reduction in experimental temperatures, we report the first direct experimental observation of the pseudogap metal in the Hubbard model. These measurements are enabled by a novel, efficient spectroscopic technique with which we resolve the opening of a partial gap, which we further correlate with a thermodynamic anomaly in the equation of state that emerges at low temperatures. Our results partially characterize the pseudogap regime and hint at a link between the pseudogap and charge order, which can be probed in future work. Furthermore, these results demonstrate the utility of quantum simulation in addressing frontier problems in correlated electron physics.

Abstract: The discovery of thousands of planets orbiting stars beyond the solar system has fundamentally shifted our view of Earth’s place in the Universe, has captivated the public imagination, and has transformed research priorities in astrophysics. We are now actively searching for atmospheres on temperate, terrestrial planets, and are developing the technical tools to find and characterize “Earth-2.0”. The goal of understanding the frequency and diversity of habitable (and inhabited) planets requires a `full system approach’ where we bring to bear multiple techniques for exoplanetary observation and a detailed understanding of the evolving stellar environments in which they live.

In this talk, I will present an overview of the multiple paths in our search for inhabited planets, from current efforts to find temperate planets with stable atmospheres around red dwarf stars to future detection of true Earth-Sun analogs with NASA’s upcoming Habitable Worlds Observatory (HWO). I will summarize recent progress and open questions in understanding the key stellar environmental variables that influence exoplanet atmospheres, focusing on observational and experimental work to characterize the high-energy photon and particle radiation that dominates atmospheric escape on rocky planets. I will conclude with a short overview of the upcoming HWO mission, current opportunities for the community to engage with the mission development, and the path to launch in the ~2040 timeframe.

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.

In this talk I will provide an overview over the history of 229-Th that has culminated in this success. Further, I will discuss the remaining efforts and challenges. Finally, I will introduce the investigations underway within the framework of the BMFTR-funded project “NuQuant”.

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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.  The quantitative description of these exotic heavy hadrons requires the diabatic representation of the Born-Oppenheimer approximation, which has led to dramatic advances in atomic and molecular physics in recent decades.

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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. In this seminar, I will present the STM from the Parker Solar Probe (PSP), including requirements relating to the plasma instrument for which I am a co-investigator. I will describe how our team used the STM to map the mission’s top-level requirements to mission success criteria and helped to eliminate any single point of failure that could end the mission prematurely. I will then present my own research on magnetic switchbacks in the PSP magnetic and plasma observations and their role in solar wind acceleration and heating. I will conclude the seminar by discussing how my research on the temporal evolution of switchbacks in the solar wind led to a new STM, and helped to chart a multidisciplinary path to designing a ground-breaking science mission concept, titled Space Weather Investigation Frontier (SWIFT), with the potential to improve space weather forecasting lead times by up to 40%.

TBA

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.

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.

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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.