A5086532981- Mechanical and Optical Resonators
- X-ray Spectroscopy and Fluorescence Analysis
- Orbital Angular Momentum in Optics
- Advanced Fiber Laser Technologies
- Electron and X-Ray Spectroscopy Techniques
- Advanced Chemical Physics Studies
- Photonic and Optical Devices
- Atomic and Molecular Physics
- Microfluidic and Bio-sensing Technologies
- Advanced MEMS and NEMS Technologies
- Advanced Fiber Optic Sensors
- Mass Spectrometry Techniques and Applications
- Nuclear Physics and Applications
- Near-Field Optical Microscopy
- Astro and Planetary Science
- Ion-surface interactions and analysis
- Cold Atom Physics and Bose-Einstein Condensates
- Astrophysics and Star Formation Studies
- Planetary Science and Exploration
- Atomic and Subatomic Physics Research
- Analytical Chemistry and Sensors
- Fullerene Chemistry and Applications
- Geophysics and Sensor Technology
- Advanced Measurement and Metrology Techniques
- Spectroscopy and Laser Applications
University of Maryland, College Park
1994-2024
Physical Measurement Laboratory
2015-2024
National Institute of Standards and Technology
2015-2024
Material Measurement Laboratory
2024
Theiss Research
2024
National Institute of Standards
2001-2021
Geosciences Paris-Saclay
2013-2014
Université Paris-Sud
1989-2013
Centre National de la Recherche Scientifique
2012-2013
Argonne National Laboratory
1993-2000
The thermal evolution of magma oceans produced by collision with giant impactors late in accretion is expected to depend on the composition and structure atmosphere through greenhouse effect CO 2 H O released from during its crystallization. In order constrain various cooling timescales system, we developed a 1‐D parameterized convection model ocean coupled radiative‐convective atmosphere. We conducted parametric study described influences initial volatile inventories, depth ocean,...
Acceleration measurement is widely used in commercial, scientific, and defense applications, but the resolution accuracy achievable for demanding applications limited by current technology to build calibrate accelerometers. We report an optomechanical accelerometer based on a Fabry–Perot microcavity silicon chip that extremely precise, field deployable, can self-calibrate. The measured acceleration highest reported date microfabricated achieved over wide frequency range ( <mml:math...
Ionization and multifragmentation have been observed in ${\mathrm{C}}_{60}$ molecules bombarded by ${\mathrm{Xe}}^{35+}$ ${\mathrm{Xe}}^{18+}$ ions with energies the range 420-625 MeV. The c.m. exceeded those used previous studies several orders of magnitude. We present mass distribution positively charged fragments together a theoretical model indicating that total interaction cross section contains roughly equal contributions from (a) excitation giant plasmon resonance, (b)...
We have measured the nondipolar contribution to Ar $1s$ photoelectron angular distribution over 30--2000 eV electron-energy range. The interaction results in a forward or backward asymmetry with respect photon beam. is directed near threshold, symmetric 230 eV, and becomes increasingly at higher energies. asymmetries are excellent agreement theoretical calculations, which include interference between electric-dipole electric-quadrupole photoionization amplitudes.
Sensing platforms based upon photonic integrated circuits have shown considerable promise; however, they require corresponding advancements in optical readout technologies. Here, we present an on-chip spectrometer that leverages thin-film lithium niobate modulator to produce a frequency-agile electro-optic frequency comb for interrogating chip-scale temperature and acceleration sensors. The chirped process allows ultralow radiofrequency drive voltages, which are as much seven orders of...
In many physical systems, the interaction with an open environment leads to energy dissipation and reduced coherence, making it challenging control these systems effectively. context of wave phenomena, such lossy interactions can be specifically controlled isolate system, a condition known as bound-state-in-continuum (BIC). Despite recent advances in engineered BICs for photonic waveguiding, practical implementations are still largely polarization- geometry-specific, underlying principles...
We report the measurement of nondipolar asymmetry parameters for angular distributions argon 1s, krypton 2s, and 2p photoemission within 2--3 keV above their respective thresholds. Pronounced asymmetries with respect to direction photon propagation are present even at low electron kinetic energies. The energy dependence is Z subshell specific causes preferred emission change sign least once in each cases studied. Towards higher energies increases photoelectron pattern forward skewed all...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMulticoincidence mass spectrometry applied to hexamethyldisilane excited around the silicon 2p edgeM. Simon, T. Lebrun, R. Martins, G. B. de Souza, I. Nenner, M. Lavollee, and P. MorinCite this: J. Phys. Chem. 1993, 97, 20, 5228–5237Publication Date (Print):May 1, 1993Publication History Published online1 May 2002Published inissue 1 1993https://pubs.acs.org/doi/10.1021/j100122a011https://doi.org/10.1021/j100122a011research-articleACS...
Fragmentation of N2O after selective core excitation terminal and central nitrogen, has been studied by a multicoincidence technique (PEPIPICO) using synchrotron radiation. We show that dissociation dynamics is dependent upon the excited site, especially in case ‘‘atomization’’ molecule. The nitrogen always found with very little kinetic energy, except Nt→Π* transition. A bent intermediate geometry proposed to explain this observation.
Optical tweezers have emerged as a powerful tool for micro- and nanomanipulation. Using optical to perform automated assembly requires on-line monitoring of components in the workspace. This paper presents algorithms estimating three-dimensional positions microspheres Algorithms presented this use images obtained by section microscopy. The are first segmented locate areas interest then image gradient information from is used individual micro spheres XY plane. Finally, signature curves...
Traditional electro-optic frequency comb spectrometers rely upon the use of an acousto-optic modulator (AOM) to provide a differential shift between probe and local oscillator (LO) legs interferometer. Here we show that these modulators can be replaced by phase (EOM) which is driven sawtooth waveform induce serrodyne modulation. This approach enables direct spectroscopy performed with single dual-drive Mach–Zehnder (DD-MZM), allowing for lower noise. Further, this method allows simpler...
${\mathrm{C}}_{60}$ vapor was bombarded by $^{136}\mathrm{Xe}^{35+}$ and $^{136}\mathrm{Xe}^{18+}$ ions in the energy range 420--625 MeV to study various ionization fragmentation processes that occur. Since center-of-mass energies used this work exceeded those of previous studies several orders magnitude, new excitation dissociation modes were expected indeed found. Positive extracted from interaction region their times flight measured both singly coincidence with other ionic fragments. A...
We demonstrate a microfabricated optomechanical accelerometer that is capable of percent-level accuracy without external calibration. To achieve this capability, we use mechanical model the device behavior can be characterized by thermal noise response along with an optical frequency comb readout method enables high sensitivity, bandwidth, dynamic range, and SI-traceable displacement measurements. The resulting intrinsic was evaluated over wide range comparing to primary vibration...
Near an absorption edge, x-ray emission cannot be treated separately from the process itself; a scattering formalism must used. Experimental data have been recorded showing xenon following excitation by tunable synchrotron radiation below and above ${\mathit{L}}_{3}$ edge. Complete sets are presented for Xe L${\mathrm{\ensuremath{\alpha}}}_{1,2}$ L${\mathrm{\ensuremath{\beta}}}_{2,15}$ 10 eV to 40 In accord with resonant-inelastic-scattering model, observed evolves resonant Raman into...
We demonstrate an increase in trapping lifetime for optically trapped nanoparticles by more than order of magnitude using feedback control, with no corresponding beam power. Langevin dynamics simulations were used to design the control law, and this technique was then demonstrated experimentally 100 nm gold particles 350 silica particles. No particle escapes detected controller on, leading lower limits on 26 times (at constant average power) 22 (with power reduced one-third). The approach...
Electro-optic frequency combs were employed to rapidly interrogate an optomechanical sensor, demonstrating spectral resolution substantially exceeding that possible with a mode-locked comb. Frequency generated using integrated-circuit-based direct digital synthesizer and utilized in self-heterodyne configuration. Unlike approaches based upon laser locking, the present approach allows rapid, parallel measurements of full optical cavity modes, large dynamic range sensor displacement,...
Cavity optomechanical sensors can offer exceptional sensitivity; however, interrogating the cavity motion with high accuracy and dynamic range has proven to be challenging. Here, we employ a dual optical frequency comb spectrometer readout microfabricated accelerometer, allowing for rapid simultaneous measurements of cavity’s displacement, finesse, coupling at accelerations up 24 g (236 m/s2). With this approach, have achieved displacement sensitivity 2 fm Hz−1/2, measurement rate 100 kHz,...
We report precise measurements of differential x-ray scattering cross sections in Ne and He from 11--22 keV develop a method for obtaining predictions comparable accuracy ( $1%$). The measurement ratios (total to Compton Rayleigh Ne) facilitates comparison theories. find evidence the need include nonlocal exchange, electron correlation, dynamic effects an accurate description at low $Z$ conclude that no single current theory is sufficient.
This paper presents a radial basis function based approach to generate simplified models estimate the trapping probability in optical experiments using offline simulations. The difference form of Langevin’s equation is used perform physically accurate simulations particle under influence potential and probabilities at discrete points parameter space. Gaussian functions combined with kd-tree partitioning space are then probability. We show that proposed computationally efficient estimating...
Abstract The objective of the proposed macroscopic quantum resonators (MAQRO) mission is to harness space for achieving long free-fall times, extreme vacuum, nano-gravity, and cryogenic temperatures test foundations physics in experiments at interface with gravity. Developing necessary technologies, required sensitivities providing isolation systems from their environment will lay path developing novel sensors. Earlier studies showed that proposal feasible but several critical challenges...
This article presents the design and performance evaluation of a six-degree-of-freedom piezoelectrically actuated fine motion stage that will be used for three dimensional error compensation long-range translation mechanism. Development single element, piezoelectric linear displacement actuator capable translations 1.67 μm with 900 V potential across electrodes under 27.4 N axial load 0.5 mm lateral distortion is presented. Finite element methods have been developed to evaluate resonant...
We measure charging of single dielectric microparticles after interaction with a glass substrate using optical tweezers to control the particle, its charge sensitivity few electrons, and precisely contact particle substrate. Polystyrene (PS) adhered can be selected based on size, shape, or properties repeatedly loaded into trap piezoelectric (PZT) transducer. Separation from leads transfer through electrification. The trapped is measured response motion step excitation uniform electric...
While a continuous Brownian description of noise from heat and pressure is adequate to model measurements with relatively long integration times, these forces are ultimately generated by quantized degrees freedom like phonons gas particles. Fundamentally, the ultimate limit this sensing problem resolve all individual system-sensor collisions. Here we propose use nanomechanical devices operated impulse readout sensitivity around standard quantum sense ultralow pressures directly counting...
Partial cross sections for Ar ${K\ensuremath{-}L}_{2}{L}_{3}{(}^{1}{D}_{2})np,$ $n=4$ and 5 spectator Auger states excited by x-ray absorption across the K edge, were measured compared with calculations based on theory of radiationless resonant Raman scattering. Core relaxation coherence among bound continuum intermediate produce shake-up, shake-down, photoelectron-recapture effects in sections. The width position $4p$ peak are shown to be sensitive resonance structure partial section via...