Schedule 2026

Dr. Yitong Zhai

From Engines to the Atmosphere: Modeling the Oxidation Chemistry of n‑Hexanol and Ethylene

Abstract: Oxidation chemistry governs fuel reactivity in combustion systems and drives pollutant formation and transformation in the atmosphere. These processes involve extensive reaction networks with numerous intermediates and competing pathways, making mechanistic interpretation challenging. Kinetic modeling provides a powerful framework for identifying dominant reaction channels, interpreting experimental observations, and predicting chemical evolution under varying conditions.

In this work, kinetic modeling is applied to two representative oxidation systems: the low‑temperature oxidation of n‑hexanol and the ozone‑assisted oxidation of ethylene. For n‑hexanol, a detailed reaction mechanism is used to elucidate the formation pathways of key oxygenated intermediates, including cyclic ethers, keto‑hydroperoxides, and diones, that play central roles in low‑temperature chain‑branching chemistry. For ethylene ozonolysis, a comprehensive mechanism is developed to describe both the initial ozone‑alkene reaction and the subsequent oxidation steps involving Criegee intermediates and keto‑hydroperoxides. Comparison with experimental measurements demonstrates that the models capture major trends in species evolution and provide mechanistic insight into the controlling reaction pathways. Together, these studies highlight the value of mechanism‑based kinetic modeling in advancing the understanding of oxidation chemistry across combustion‑relevant and atmospheric environments.

Aakash Gupta

PhD Defense

Title: Deciphering Ultrafast Photoinduced and Photocatalytic Reaction Dynamics on Oxide Surfaces: Direct Detection of Radical Intermediates, Fragment Trapping, and Carbon–Carbon, Carbon–Oxygen, and Carbon–Hydrogen Bond Formation Pathways

Abstract: Understanding photoinduced reactions at solid interfaces is essential for advancing heterogeneous photocatalysis, surface photochemistry, and energy conversion technologies. This dissertation investigates the ultrafast dynamics of reactive intermediates, fragment trapping, and radical-mediated bond formation on oxide surfaces using time-of-flight mass spectrometry in conjunction with femtosecond pump-probe spectroscopy.  Various experimental findings are validated through collaborations via density functional theory (DFT). By combining temporal, mass, and energy-resolved measurements, this work provides molecular-level insight into the elementary processes governing light-driven surface reactions. The photodissociation dynamics of CH₃I adsorbed on TiO₂(110), TiO₂(100), and amorphous silicon oxide surfaces are examined as model systems for photoinduced surface chemistry. On TiO₂(110), direct detection of transient intermediates reveals that photogenerated fragments can become trapped at the surface, passivating reactive sites and modifying the interfacial potential energy landscape. This fragment trapping stabilizes a previously unobserved CH₃ICH₃ intermediate, which alters ultrafast reaction pathways and produces coherent oscillations in transient CH₃⁺signals. Complementary DFT calculations identify the vibrational modes and dissociation pathways associated with this intermediate. Photocatalytic water splitting on TiO₂(100) is further investigated through direct observation of elusive intermediates, including D, OD, and OOD species generated from D₂O photodissociation. In the presence of CH₃I, additional reaction pathways lead to methane and methanol formation through coupling between water-derived species and methyl fragments. Temperature-dependent measurements and DFT calculations clarify the mechanisms governing these photocatalytic reactions. This dissertation also demonstrates ultrafast carbon–carbon bond formation on amorphous silicon oxide surfaces following CH₃I photodissociation. Time-resolved detection of C2 fragments provides direct evidence of methyl radical coupling, with product formation observed as early as ~0.5 ps after excitation. Collectively, these studies reveal how fragment trapping, energy dissipation, and radical interactions govern ultrafast surface reactivity, establishing new insights into photocatalytic and heterogeneous photochemical processes at oxide interfaces.]

Alec C. DeCecco

Abstract: Jet‑stirred reactors (JSRs), also known as zero‑dimensional reactors, provide highly uniform and nearly isothermal environments that make them exceptionally well suited for fundamental kinetic studies. Despite these advantages, adapting JSRs for heterogeneous catalysis remains nontrivial, as it requires effective integration of solid catalysts into a flow system originally designed for gas‑phase chemistry. In addition, the implementation of chemically specific, in situ diagnostics within JSRs poses further challenges, limiting their broader application in mechanistic investigations. Here, we present a catalytic jet‑stirred reactor (CJSR) designed to accommodate solid catalyst pellets while enabling systematic variation of temperature, residence time, feed composition, and effective catalytic surface area. The reactor is coupled to molecular‑beam sampling and a reflectron time‑of‑flight mass spectrometer with tunable vacuum‑ultraviolet (VUV) single‑photon ionization, allowing in situ detection of reaction products and identification of selected species via photoionization efficiency (PIE) measurements. The capabilities of this approach are demonstrated using Fischer–Tropsch synthesis (FTS) over La_0.75Sr_0.25Fe_0.95Ru_0.05O₃ ± δ at near‑atmospheric pressure, temperatures of 340–490 K, residence times of 3–5 s, and H₂:CO ratios from 1:1 to 5:1. A broad distribution of hydrocarbon products was observed. C₁–C₇olefins and paraffins were detected, and several key products were identified by comparison of measured PIE curves with literature reference data; higher‑mass hydrocarbons were observed up to C₁₂ with their signals exhibiting strong sensitivity to operating parameters.

This approach is then leveraged to gain mechanistic insight into the conversion of methanol to olefins (MTO) over acidic zeolite catalysts. MTO is a promising approach for producing important chemical commodities from nonpetroleum feedstocks. While MTO has been studied extensively, a thorough understanding of the catalytic mechanism has remained hindered due to difficulty in detecting and identifying key reactive intermediates and radicals. For instance, initial olefin formation has been proposed to follow various mechanisms relying on the formation of gas phase intermediates such as formaldehyde, ketene, and acetaldehyde.

In this work we employ the CJSR–molecular‑beam VUV‑PI–TOFMS approach to investigate the MTO reaction over commercial zeolite catalysts H-ZSM-5 and SAPO-34 at near atmospheric pressure, temperature range of 250-450 °C, residence times of 1-5 s, and methanol concentrations of 4-6 %. Gas-phase species are sampled micrometers away from the catalyst surface, where the reaction is effectively quenched as intermediates and products are rapidly extracted into the molecular beam vacuum setup. Detected species include small olefins (i.e., ethylene, propene, n-butene, etc.) and various oxygenated intermediates including aldehydes, alcohols, carboxylic acids, and ethers. In addition to these final products, methoxy radicals are also detected. Together these investigations illustrate the utility of the CJSR–molecular‑beam VUV‑PI–TOFMS approach for rapid parametric mapping and mechanistic interrogation of complex heterogeneous catalytic reaction systems under well‑defined mixing and thermal conditions.

Dr. Volodymyr Turkowski

Dynamical Mean-Field Theory for materials with strong electron-electron correlations

Abstract: Materials with strong electron correlations (strong on-site repulsion between electrons) demonstrate many unusual physical phenomena that are used or have a great potential to be used in novel technologies. To understand and control their properties one needs to use theoretical tools beyond the standard approaches. In this presentation, I will discuss main physical properties of such materials and the relevant theoretical approach  – Dynamical Mean-Field Theory (DMFT) developed to describe their characteristics. I will proceed with details on how DMFT is combined with an ab initioDensity Functional Theory (DFT) into a state-of-the-art DFT+DMFT approach widely used to analyze properties of strongly correlated materials. I will conclude with several important examples of the application of DFT+DMFT to describe very interesting and non-trivial physical phenomena in different systems with strong electron correlations.

Dr. Marisol Alcantara Ortigoza

Short story of the journey from the intractable many-body Schrödinger equation to the computational design of spin qubits for quantum technologies

Abstract: Shortly after the success of the stationary Schrödinger’s equation (actually its solution) to describe the hydrogen atom, it became clear that describing almost anything else was simply intractable. This is mainly because even a “simple” helium atom or a hydrogen molecule is a many-body problem, but also because of the fermionic nature of the electrons, including indistinguishability. In 1965 Richard Feynman proposed that a “quantum computer” able to exploit the quantum-mechanics principles (interference, superposition, and entanglement) would be more efficient to model the quantum many-body problem behavior found in condensed matter physics. Still, as enticing as that may seem, here we are today, designing and testing the building blocks of future quantum computers  spin qubits, using our “old” transistor-based computers… And yet, it is equally fascinating how physicists have been able to solve Schrödinger’s equation for extended solids, surfaces, nanoparticles, molecules, etc., without quite knowing the full equation at hand! Not only that, it is now even possible to model how matter interacts with light from quantum first principles, which is at the core of the functionality of spin qubits. Nowadays, of course, the prospective applications of quantum computers is well beyond condensed matter exact description and have expanded to the advancement of research areas such as clean energy, drug design, and big data science, to mention a few. These technologies, however, are at their infancy because ideal “spin qubits” are yet to be found. In this talk, I will walk you through some of the breakthroughs that allow us today to design and computationally test the functionality of complex systems such as spin qubits embedded in solids or 2D materials, and share with you some of the main contributions to the topic from our own research, here at the University of Central Florida and Tuskegee University.

Dr. Takat Rawal

Atomistic Modeling of Functional Nanomaterials for Energy Applications 

Abstract: The growing global demand for energy is driving the development of advanced functional materials that are essential to modern energy technologies. Among various materials, single-atom catalysts (SACs) represent an emerging class of materials in which isolated metal atoms are dispersed on a support material. Their tunable coordination environment and electronic structures have made them unique for exceptional catalytic activity and selectivity. Computational design of SACs presents both significant opportunities and challenges. I will talk about how the use of combined approach of density functional theory (DFT), computational methods, and high-performance computing can be used to perform atomistic modeling of materials that allow to investigate electronic structures, adsorption of atoms/molecules on solid surfaces and interfaces, and surface reactions. In my talk, I will provide a few examples of SACs and describe their electronic and catalytic properties. One example is ceria-supported Ru single atom which can be stabilized on the (110) surface via substitution for a surface Ce atom and can be coordinated with four oxygen atoms in a squared planar geometry. Due to its unique local electronic properties, single dispersed Ru atom can serve as an active site for CO2 adsorption. The CO2-Ru/CeO2 interaction is dominated by hybridization of C 2p and Ru 4d orbitals. Furthermore, I will show that how the manipulation of atomic structures and local electronic properties can influence the reactivity of Ru SACs towards RWGS reaction. At the end, I will talk about how the integration of artificial intelligence (AI) with physics-based modeling can help accelerate simulation of nanomaterials and can support the research and development of advanced materials for energy applications as promising avenues for future materials research.

UCF Interactive Campus MapPSB – Physical Sciences Building

R1-Bldg. – Research 1 Building

HEC-L3Harris Corporation Engineering Center

TCH – Trevor Colbourn Hall

Live Oak

RWC – Recreation and Wellness Center

Schedule 2025

REU Talk 1: Nils Bernhardt, Technische Universität Berlin

Characterization of UV Color Centers in Hexagonal Boron Nitride

Friday, May 23, 2023, 10-11am, R1

Abstract: Hexagonal boron nitride (hBN) is an ultra-wide bandgap (~ 6 eV; ~ 206 nm) material with a graphene-like structure. The large bandgap makes it interesting not only for power electronics but also for optical devices. Its van der Waals inter-layer bonds allow direct exfoliation into atomically thin films, rendering it particularly valuable for quantum emitter applications where dimensional confinement and material purity are crucial. Defect quantum emitters in hBN are particularly interesting because they exhibit bright, stable single-photon sources at room temperature, a key requirement for quantum technologies such as secure communications, quantum computing, and advanced sensing. While such quantum emitters have been extensively studied for the near-infrared (IR) and visible regime in hBN, their structural origin is often still elusive. In contrast, ultraviolet (UV) luminescence from hBN defects presents unique opportunities and challenges. For instance, while many novel emitters continue to emerge, the well-established 4.1 eV (303 nm) defect shows a high binding energy far exceeding the thermal energy at room temperature. Consequently, such emitters are stable and have a low probability of thermal dissociation or decay, increasing the reliability of radiated photons. However, site-specific engineering of these defects remains an unsolved challenge. Our investigation provides a comprehensive study of the emission intensity, excitation channels, and carrier dynamics as a function of temperature for several UV emitters. We employ photoluminescence excitation (PLE) spectroscopy alongside temperature-dependent and time-resolved photoluminescence spectroscopy measurements to explore the origin and properties of established as well as newly identified defect luminescences. As such, we aim to promote the understanding of how material composition tuning affects defect formation and luminescence properties in hBN for the UV spectral region by establishing a correlation between growth conditions and luminescence characteristics.

Dr. Duy Le, University of Central Florida

Computational Design of Advanced Materials for Energy Applications

Friday, May 23, 2025, 1:30 pm, PSB 160/161

Abstract: Fossil fuels have long served as the world’s primary energy source. Synthetic fuels offer a promising alternative; help reduce our dependence on fossil fuels. Developing optimized catalyst materials is crucial for improving production of synthetic fuels. Alongside experimental work, computational modeling plays a key role in advancing the design of enhanced catalysts for sustainable, fossil fuel-free fuel production. In the first part of my talk, I will discuss our computational modeling efforts to leverage the electronic structures of two-dimensional materials for catalytic applications. Specifically, I will demonstrate that the defect-laden basal plane of hexagonal boron nitride (h-BN) can catalyze CO₂ hydrogenation to value-added products at nitrogen-vacancy (VN) sites. This catalytic activity arises from the isolated electronic states created by these defects. In the second part, I will discuss the role of non-metal cations, such as ammonium (NH₄⁺) and methylammonium (CH₃NH₃⁺) cations, in electrocatalysis. I will show how these cations can alter reaction pathways, enhancing both CO₂ electroreduction and the hydrogen evolution reaction.

REU Talk 2

Keith Blackman, University of Central Florida

Title: Monitoring the formation of Cn (n=2,3,4) products after photodissociation of CH₃I on fully oxidized and partially reduced

Abstract:Carbon-carbon (C-C) bond formation is paramount for a wide range of industrial and manufacturing processes, including commodities, synthetics, pharmaceuticals, and cosmetics. Understanding the C-C bond formation in heterogeneous catalytic reactions at gas-solid interfaces, and the corresponding surface properties, could be integral to improving the efficiency of various catalysts and catalytic processes.
This study focuses on understanding how single carbon (C₁) species are transformed into multi-carbon species (C_n, n=2,3,4) species through the coupling of CH₃ radicals, and how these species evolve on fully oxidized and reduced TiO₂(110) surfaces. Methyl iodide, employed as a precursor for CH₃ radicals, is continuously dosed on a TiO₂(110) surface held at 150 K and irradiated by femtosecond laser pulses with a central wavelength of 266 nm, power of 300 mW/cm², and repetition rate of 1 KHz. The central wavelength and the intensity of the laser beam are carefully tuned to excite CH₃I into the dissociated A-band, which leads to the formation of neutral CH₃ and I radicals as well as to ionize the reaction intermediates and final products. The ions produced at the surface are detected and analyzed with a time-of-flight mass spectrometer.
The mass spectra reveal the formation of C_n (n=2,3,4) products, such as C₂H₆, C₂H₅, C₂H₄, C₃H₇, C₃H₅, and C₄H₁₀, as well as H₂O. The detection of alkanes and alkenes species along with H₂O indicates an oxidative dehydrogenation process at the surface. Monitoring the yields of these products as a function of laser irradiation and surface degree of oxidation, which will also be presented in this contribution, is critical to fully understand the catalytic reaction mechanism at the oxide surface. This type of investigation could provide important insight into the C-C bond formation on other metal oxide surfaces using a variety of precursor molecules.

REU Talk 3

Ms. S. Faiza Sherazi, University of Central Florida

Tuesday, 6/17/2025, R1 Bldg, Room 103

Revealing Local Coordination of Ag Single Atom Catalyst Supported on CeO₂(110), ZrO₂(1̅11), and Al₂O₃(111)

Abstract: Single atom catalyst (SAC) supported on metal oxide surfaces is a promising candidate for various reactions as it possesses high temperature stability and potentially high selectivity. Determining the SAC’s local atomic coordination and geometric structure is important for understanding its catalytic performance. In this work, we apply the ab initio thermodynamics approach to investigate the coordination environment of Ag SAC supported on CeO₂(110), ZrO2₂(1̅11), and Al₂O₃(111), chosen as accompanying experimental observations find the former to be a more viable support than the latter. We find that the Ag SAC structure in which Ag is embedded in the CeO₂ lattice with one surface oxygen vacancy nearby is the most favorable on the CeO2(110) surface while the structure in which Ag embeds in the ZrO₂ and Al₂O₃ lattice without any oxygen vacancy nearby is the most favorable on the ZrO₂(1̅11) and Al2O3(111) surfaces, respectively. Our results also show that it is easier to create oxygen vacancy near the Ag atom when the support is CeO₂(110) than ZrO₂(1̅11) and Al₂O₃(111). We compare the trends in the energetics of NH3 adsorption and dissociation on Ag SAC supported on CeO2(110) with those on ZrO2(1̅11) and Al2O3(111) to compare with accompanying experimental observations that find the ceria-supported Ag SAC to exhibit a pronounced selectivity in ammonia oxidation. We will report experimental data to compare with our findings and comment on their implications for the catalytic performance of the Ag SAC. Work is supported by the National Science Foundation grant CHE-1955343.

Making sense of distributed quantum computing  

Abstract: The emergence of various quantum technologies has profound implications in advancing scientific discoveries in the many forefronts. One of the prominent applications is quantum chemistry which uses quantum computers to simulate the quantum processes in material synthesis and predict material properties that are beyond the capabilities of classical computers. In this talk, we will review the state-of-the-art quantum hardware platforms from the perspective of quantum information processing. We will discuss the challenges towards the “quantum supremacy” and the necessity for a unified and interconnected quantum network for a scalable distributed quantum computing architecture. I will outline the key technical ingredients for building a network of quantum processors and showcase our efforts in interconnecting distant superconducting quantum systems with optical fibers. We will end by sharing a prospect on how the infrastructure of global internet can be exploited to make quantum computation practical and universal.

Grain boundary movement in single-layer hexagonal boron nitride: insights from molecular dynamics simulation using machine-learned potentials

Abstract: Grain boundaries are commonly found in materials regardless of the growth method and their presence is not always desirable. While there could be some unique properties that come with grain boundaries, many material applications rely on pristine, single crystalline materials.  Being able to stimulate and predict the motion of grain boundaries would be beneficial in developing methodology for improving the quality of materials for which single crystalline structures are desirable.  In this work, we present first the details of a machine-learned potential that we have developed using the Allegro architecture and attest to its robustness. We next present results of molecular dynamics simulations of hexagonal boron nitride (h-BN) that investigate the movement of 4|8 grain boundaries.  These simulations are carried out with ~10,000 atoms to allow for mimicking realistic size of the system.  Our calculations of the activation energy barriers show that the initial movement requires a large amount of energy (~2.2eV). However, subsequent movements of the grain boundary unit need a much lower the barrier (<0.5eV).  Our results suggest that if the first movement could be stimulated, then the rest of the grain boundary has a high chance of following that motion to directionally diffuse to the edge of the h-BN sheet. These results provide some guidelines for removing grain boundaries in the h-BN which, when defect-laden, is a promising material for both catalysis and single photon emission.