Patrick L. Kramer
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View article: Terahertz-field activation of polar skyrons
Terahertz-field activation of polar skyrons Open
Unraveling collective modes arising from coupled degrees of freedom is crucial for understanding complex interactions in solids and developing new functionalities. Unique collective behaviors emerge when two degrees of freedom, ordered on …
View article: Tracking Electron, Proton, and Solvent Motion in Proton-Coupled Electron Transfer with Ultrafast X-rays
Tracking Electron, Proton, and Solvent Motion in Proton-Coupled Electron Transfer with Ultrafast X-rays Open
Proton-coupled electron transfer (PCET) is foundational to catalysis, bioenergetics, and energy conversion, yet capturing and disentangling the coupled motions of electrons, protons, and solvent has remained a major experimental challenge.…
View article: Joint commensuration in moiré charge-order superlattices drives shear topological defects
Joint commensuration in moiré charge-order superlattices drives shear topological defects Open
The advent of two-dimensional moiré systems has revolutionized the exploration of phenomena arising from strong correlations and nontrivial band topology. Recently, a moiré superstructure formed by two coexisting charge density wave (CDW) …
View article: High-resolution <i>in situ</i> characterization of laser powder bed fusion via transmission X-ray microscopy at X-ray free-electron lasers
High-resolution <i>in situ</i> characterization of laser powder bed fusion via transmission X-ray microscopy at X-ray free-electron lasers Open
In this work, we describe the instrumentation used to perform the first operando transmission X-ray microscopy (TXM) and simultaneous X-ray diffraction of laser melting simulating laser powder bed fusion on the XCS instrument at the Linac …
View article: Electrochemical Control of the Ultrafast Lattice Response of a Layered Semimetal
Electrochemical Control of the Ultrafast Lattice Response of a Layered Semimetal Open
The unique layer‐stacking in two‐dimensional (2D) van der Waals materials facilitates the formation of nearly degenerate phases of matter and opens novel routes for the design of low‐power, reconfigurable functional materials. Electrochemi…
View article: Ultrafast Symmetry Control in Photoexcited Quantum Dots
Ultrafast Symmetry Control in Photoexcited Quantum Dots Open
Symmetry control is essential for realizing unconventional properties, such as ferroelectricity, nonlinear optical responses, and complex topological order, thus it holds promise for the design of emerging quantum and photonic systems. Nev…
View article: Ultrafast symmetry control in photoexcited quantum dots
Ultrafast symmetry control in photoexcited quantum dots Open
Symmetry control is essential for realizing unconventional properties, such as ferroelectricity, nonlinear optical responses, and complex topological order, thus it holds promise for the design of emerging quantum and photonic systems. Nev…
View article: Imaging ultrafast electronic domain fluctuations with X-ray speckle visibility
Imaging ultrafast electronic domain fluctuations with X-ray speckle visibility Open
Speckle patterns manifesting from the interaction of coherent X-rays with matter offer a glimpse into the dynamics of nanoscale domains that underpin many emergent phenomena in quantum materials. While the dynamics of the average structure…
View article: Terahertz-induced tunnel ionization drives coherent Raman-active phonon in Bismuth
Terahertz-induced tunnel ionization drives coherent Raman-active phonon in Bismuth Open
Driving coherent lattice motion with THz pulses has emerged as a novel pathway for achieving dynamic stabilization of exotic phases that are inaccessible in equilibrium quantum materials. In this work, we present a previously unexplored me…
View article: Time-Resolved X-ray Emission Spectroscopy and Synthetic High-Spin Model Complexes Resolve Ambiguities in Excited-State Assignments of Transition-Metal Chromophores: A Case Study of Fe-Amido Complexes
Time-Resolved X-ray Emission Spectroscopy and Synthetic High-Spin Model Complexes Resolve Ambiguities in Excited-State Assignments of Transition-Metal Chromophores: A Case Study of Fe-Amido Complexes Open
To fully harness the potential of abundant metal coordination complex photosensitizers, a detailed understanding of the molecular properties that dictate and control the electronic excited-state population dynamics initiated by light absor…
View article: The Liquid Jet Endstation for Hard X-ray Scattering and Spectroscopy at the Linac Coherent Light Source
The Liquid Jet Endstation for Hard X-ray Scattering and Spectroscopy at the Linac Coherent Light Source Open
The ability to study chemical dynamics on ultrafast timescales has greatly advanced with the introduction of X-ray free electron lasers (XFELs) providing short pulses of intense X-rays tailored to probe atomic structure and electronic conf…
View article: Terahertz-Driven Local Dipolar Correlation in a Quantum Paraelectric
Terahertz-Driven Local Dipolar Correlation in a Quantum Paraelectric Open
Light-induced ferroelectricity in quantum paraelectrics is a new avenue of achieving dynamic stabilization of hidden orders in quantum materials. In this Letter, we explore the possibility of driving a transient ferroelectric phase in the …
View article: Terahertz-driven Local Dipolar Correlation in a Quantum Paraelectric
Terahertz-driven Local Dipolar Correlation in a Quantum Paraelectric Open
Light-induced ferroelectricity in quantum paraelectrics is a new avenue of achieving dynamic stabilization of hidden orders in quantum materials. In this work, we explore the possibility of driving transient ferroelectric phase in the quan…
View article: Bulk-like and Interfacial Water Dynamics in Nafion Fuel Cell Membranes Investigated with Ultrafast Nonlinear IR Spectroscopy
Bulk-like and Interfacial Water Dynamics in Nafion Fuel Cell Membranes Investigated with Ultrafast Nonlinear IR Spectroscopy Open
The water confined in the hydrophilic domains of Nafion fuel cell membranes is central to its primary function of ion transport. Water dynamics are intimately linked to proton transfer and are sensitive to the structural features and lengt…
View article: Reorientation-induced Stokes shifts caused by directional interactions in electronic spectroscopy: Fast dynamics of poly(methyl methacrylate)
Reorientation-induced Stokes shifts caused by directional interactions in electronic spectroscopy: Fast dynamics of poly(methyl methacrylate) Open
Dynamic Stokes shift measurements report on structural relaxation, driven by a dipole created in a chromophore by its excitation from the ground electronic state to the S1 state. Here, we demonstrate that it is also possible to have an add…
View article: Water Dynamics in Polyacrylamide Hydrogels
Water Dynamics in Polyacrylamide Hydrogels Open
Polymeric hydrogels have wide applications including electrophoresis, biocompatible materials, water superadsorbents, and contact lenses. The properties of hydrogels involve the poorly characterized molecular dynamics of water and solutes …
View article: Water Dynamics in 1-Alkyl-3-methylimidazolium Tetrafluoroborate Ionic Liquids
Water Dynamics in 1-Alkyl-3-methylimidazolium Tetrafluoroborate Ionic Liquids Open
The effects of water concentration and varying alkyl chain length on the dynamics of water in 1-alkyl-3-methylimidazolium tetrafluoroborate room-temperature ionic liquids (RTILs) were characterized using two-dimensional infrared (2D IR) vi…
View article: Ionic Liquid versus Li<sup>+</sup> Aqueous Solutions: Water Dynamics near Bistriflimide Anions
Ionic Liquid versus Li<sup>+</sup> Aqueous Solutions: Water Dynamics near Bistriflimide Anions Open
The ultrafast dynamics of concentrated aqueous solutions of the salt lithium bistriflimide and ionic liquid (IL) 1-ethyl-3-methylimidazolium bistriflimide was studied using two-dimensional infrared (2D IR) vibrational echo and polarization…
View article: Structural and Rotational Dynamics of Carbon Dioxide in 1-Alkyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquids: The Effect of Chain Length
Structural and Rotational Dynamics of Carbon Dioxide in 1-Alkyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquids: The Effect of Chain Length Open
Ionic liquids (ILs) have been proposed as possible carbon dioxide (CO2) capture media; thus, it is useful to understand the dynamics of both the dissolved gas and its IL environment as well as how altering an IL affects these dynamics. Wit…
View article: Quasi-rotating frame: accurate line shape determination with increased efficiency in noncollinear 2D optical spectroscopy
Quasi-rotating frame: accurate line shape determination with increased efficiency in noncollinear 2D optical spectroscopy Open
Multidimensional spectroscopies correlate the oscillation frequencies of an atomic or molecular resonance during at least two different time periods. For two-dimensional (2D) optical spectroscopy, oscillations in the first coherence period…
View article: Carbon dioxide in an ionic liquid: Structural and rotational dynamics
Carbon dioxide in an ionic liquid: Structural and rotational dynamics Open
Ionic liquids (ILs), which have widely tunable structural motifs and intermolecular interactions with solutes, have been proposed as possible carbon capture media. To inform the choice of an optimal ionic liquid system, it can be useful to…
View article: Separation of experimental 2D IR frequency-frequency correlation functions into structural and reorientation-induced contributions
Separation of experimental 2D IR frequency-frequency correlation functions into structural and reorientation-induced contributions Open
A vibrational transition frequency can couple to its environment through a directional vector interaction. In such cases, reorientation of the vibrational transition dipole (molecular orientational relaxation) and its frequency fluctuation…
View article: Observation and theory of reorientation-induced spectral diffusion in polarization-selective 2D IR spectroscopy
Observation and theory of reorientation-induced spectral diffusion in polarization-selective 2D IR spectroscopy Open
In nearly all applications of ultrafast multidimensional infrared spectroscopy, the spectral degrees of freedom (e.g., transition frequency) and the orientation of the transition dipole are assumed to be decoupled. We present experimental …