A5060681003- Laser-Matter Interactions and Applications
- Advanced Chemical Physics Studies
- Advanced Fiber Laser Technologies
- Mass Spectrometry Techniques and Applications
- Atmospheric chemistry and aerosols
- Orbital Angular Momentum in Optics
- Spectroscopy and Laser Applications
- Catalytic Processes in Materials Science
- Catalysis and Oxidation Reactions
- Advanced Combustion Engine Technologies
- Photonic Crystal and Fiber Optics
- Photoreceptor and optogenetics research
- Laser-Plasma Interactions and Diagnostics
- Spectroscopy and Quantum Chemical Studies
- Fullerene Chemistry and Applications
- Electrochemical Analysis and Applications
- Photochemistry and Electron Transfer Studies
- Advanced Thermodynamics and Statistical Mechanics
- Catalytic Alkyne Reactions
- Free Radicals and Antioxidants
- Chemical Reaction Mechanisms
- Radical Photochemical Reactions
- Recycling and Waste Management Techniques
- Chemical Reactions and Mechanisms
- Synthesis and Properties of Aromatic Compounds
United States Air Force Academy
2024
Sandia National Laboratories California
2021-2024
University of Colorado Boulder
2016-2020
Joint Institute for Laboratory Astrophysics
2016-2020
Sandia National Laboratories
2020
Pulses with a twist and torque Structured light beams can serve as vortex carrying optical angular momentum have been used to enhance communications imaging. Rego et al. generated dynamic pulses by interfering two incident time-delayed different orbital momenta through the process of high harmonic generation. A controlled time delay between allowed extreme-ultraviolet beam exhibit time-dependent momentum, called self-torque. Such could potentially be manipulate nanostructures atoms on...
Vacuum-ultraviolet (VUV) light is critical for the study of molecules and materials, but generation femtosecond pulses in VUV region at high repetition rates has proven difficult. Here we demonstrate efficient megahertz using highly cascaded four-wave mixing processes a negative-curvature hollow-core fiber. Both even- odd-order harmonics are generated up to 15th harmonic (69 nm, 18.0 eV), with energy resolution <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Rapid molecular-weight growth of hydrocarbons occurs in flames, industrial synthesis, and potentially cold astrochemical environments. A variety high- low-temperature chemical mechanisms have been proposed confirmed, but more facile pathways may be needed to explain observations. We provide laboratory confirmation a controlled pyrolysis environment recently mechanism, radical-radical chain reactions resonance-stabilized species. The recombination reaction phenyl (c-C6 H5 ) benzyl CH2...
Synthetic routes to the 10π Hückel aromatic azulene (C10H8) molecule, simplest polycyclic hydrocarbon carrying an adjacent five- and seven-membered ring, have been of fundamental importance due role - a structural isomer naphthalene as essential molecular building block saddle-shaped carbonaceous nanostructures such curved nanographenes nanoribbons. Here, we report on very first gas phase preparation by probing gas-phase reaction between two resonantly stabilized radicals, fulvenallenyl...
The reactions of ortho-benzyne ( o -C 6 H 4 ) with resonance-stabilized radicals lead to multiring species and specifically 5-member-rings, contributing molecular-weight growth production curved PAHs.
We report the development of a new three-dimensional (3D) momentum-imaging setup based on conventional velocity map imaging to achieve coincidence measurement photoelectrons and photo-ions. This uses only one detector (microchannel plates (MCP)/phosphor screen) but voltages electrodes are pulsed push both electrons ions toward same detector. The ion-electron is achieved using two cameras capture images separately. time-of-flight read out from MCP digitizer. demonstrate this system by...
Significance Highly excited states of neutral molecules behave qualitatively differently than the lower that are commonly studied in photochemistry. Such involved ionospheric and astrochemical phenomena, as well detonation processes. However, highly poorly understood due to experimental theoretical challenges probing their complex dynamics. Here, we apply vacuum-UV femtosecond laser sources an imaging photoelectron–photoion coincidence spectrometer directly probe surprisingly fast 25-fs...
Understanding the ultrafast dynamics of highly excited electronic states small molecules is critical for a better understanding atmospheric and astrophysical processes, as well designing coherent control strategies manipulating chemical dynamics. In states, nonadiabatic coupling, electron–electron interactions, high density govern However, these are computationally experimentally challenging to access. Fortunately, new sources vacuum ultraviolet pulses, in combination with electron–ion...
We report the combination of tabletop vacuum ultraviolet photoionization with photoion-photoelectron coincidence spectroscopy for sensitive, isomer-specific detection nascent products from a pyrolysis microreactor. Results on several molecules demonstrate two essential capabilities that are very straightforward to implement: ability differentiate isomers and distinguish thermal dissociative ionization. Here, light is derived commercial femtosecond laser system, allowing data be collected at...
Dimethyl ether (DME) oxidation is a model chemical system with small number of prototypical reaction intermediates that also has practical importance for low-carbon transportation. Although it been studied experimentally and theoretically, ambiguity remains in the relative competing DME pathways low-temperature autoignition regime. To focus on primary reactions autoignition, we measured time-resolved concentration five intermediates, CH3OCH2OO (ROO), OOCH2OCH2OOH (OOQOOH), HOOCH2OCHO...
Light beams with self-torque –a temporal variation of their orbital angular momentum– are described and produced for the first time. This new property light is naturally mapped onto extreme-ultraviolet waveforms via high-harmonic generation.
Abstract Rapid molecular‐weight growth of hydrocarbons occurs in flames, industrial synthesis, and potentially cold astrochemical environments. A variety high‐ low‐temperature chemical mechanisms have been proposed confirmed, but more facile pathways may be needed to explain observations. We provide laboratory confirmation a controlled pyrolysis environment recently mechanism, radical–radical chain reactions resonance‐stabilized species. The recombination reaction phenyl (c‐C 6 H 5 ) benzyl...
We demonstrate cascaded harmonic generation to 9th (115nm) of 1040nm in a negative curvature hollow fiber filled with Xenon gas. By injecting the fundamental and second commercial ultrafast laser at 520nm respectively, 3rd is generated sufficient efficiency produce phase matched harmonics 4th (260nm), 5th (205nm), 6th (173nm), 7th (148nm), 8th (130nm), from non-resonant process. © 2019 The Author(s)
We demonstrate cascaded harmonic generation to 9th (115nm) of 1040nm in a negative curvature hollow fiber filled with Xenon gas. By injecting the fundamental and second commercial ultrafast laser at 520nm respectively, 3rd is generated sufficient efficiency produce phase matched harmonics 4th (260nm), 5th (205nm), 6th (173nm), 7th (148nm), 8th (130nm), from non-resonant process.
Excited electronic states near 8.0 eV are studied using femtosecond PEPICO spectroscopy, accessing dense manifolds of strongly coupled states. Ionization to multiple cation is crucial for navigating the mixed this energy regime.
Light beams with self-torque -a temporal variation of their orbital angular momentum-are described and produced for the first time. This new property light is naturally mapped onto extreme-ultraviolet waveforms via high-harmonic generation. © 2019 The Author(s)
Using a cascaded four-wave-mixing process in negative-curvature fibers, we produce high-flux, high-rep-rate femtosecond pulses of UV and VUV light with wavelengths as short 115 nm, applications spectroscopy materials science.
Light beams carrying orbital angular momentum (OAM) are well known due to their powerful capabilities for applications in many fields, such as optical communications, microscopy, quantum optics, information or microparticle manipulation. In this work we introduce a new class of light that possess unique property associated with temporal variation OAM: the self-torque light. Despite recent progress generation designer ultrafast waveforms OAM, up now there is no evidence creation pulses...
Utilizing highly cascaded harmonic generation, we upconvert a MHz fiber laser to the vacuum ultraviolet (up 18 eV). We apply source combustion-chemistry experiments and conduct numerical simulation understand nonlinear generation process.