A5007775504- Atomic and Molecular Physics
- Laser-induced spectroscopy and plasma
- X-ray Spectroscopy and Fluorescence Analysis
- Mass Spectrometry Techniques and Applications
- Magnetic confinement fusion research
- Advanced Chemical Physics Studies
- Ionosphere and magnetosphere dynamics
- Astrophysical Phenomena and Observations
- Nuclear Physics and Applications
- Laser-Plasma Interactions and Diagnostics
- Analytical Chemistry and Chromatography
- Nuclear physics research studies
- Electron and X-Ray Spectroscopy Techniques
- Astrophysics and Star Formation Studies
- Ion-surface interactions and analysis
- Stellar, planetary, and galactic studies
- Particle accelerators and beam dynamics
- Solar and Space Plasma Dynamics
- Plasma Diagnostics and Applications
- Muon and positron interactions and applications
- Astro and Planetary Science
- Atomic and Subatomic Physics Research
- Particle Accelerators and Free-Electron Lasers
- Scientific Measurement and Uncertainty Evaluation
- Particle Detector Development and Performance
University of California, Berkeley
2013-2025
École Polytechnique Fédérale de Lausanne
2022
Weatherford College
2022
Prism Computational Sciences (United States)
2022
Tsinghua University
2008-2019
Chengdu University of Information Technology
2017
Shenyang Aerospace University
2017
Max Planck Institute for Radio Astronomy
2015
Max Planck Society
2015
University of California, San Diego
2012
We present a systematic study of the role indirect processes in soft X-ray line formation iron L-shell ions, using newly developed, relativistic, multiconfigurational atomic package. These involve neighboring charge states target ion, namely, radiative recombination, dielectronic and resonance excitation. For Fe XVII, inner-shell collisional ionization (CI) is also relevant. Lines originating from 3s 3p upper levels XVII-XX are found to be significantly affected by these processes, with some...
We present the first high-resolution, soft X-ray spectrum of prototypical Seyfert 2 galaxy, NGC 1068. This was obtained with XMM-Newton Reflection Grating Spectrometer (RGS). Emission lines from H-like and He-like low-Z ions (from C to Si) Fe L-shell dominate spectrum. Strong, narrow radiative recombination continua (RRCs) for several are also present, implying that most observed emission arises in low-temperature plasma (kTe ~ a few eV). is photoionized by inferred nuclear continuum...
Integrin adhesion receptors participate in two-way transfer of information across the plasma membrane. For example, cytoplasmic events, such as activation protein kinase C, cause an increase fibrinogen (Fg) binding affinity extracellular domain integrin alpha IIb beta 3 (inside-out signaling). Conversely, ligand to results generation intracellular signals. We used anti-LIBS2, anti-beta monoclonal antibody, understand potential mechanisms this bidirectional signaling. Anti-LIBS2 bound with...
In addition to mass accuracy, the ability of a spectrometer faithfully measure isotopic distribution an ion, defined as spectral is also important. Although time-of-flight spectrometers are reported possess high accuracy capability compared with other spectrometers, Orbitrap has not yet been investigated. Ten natural products (moxidectin, erythromycin, digoxin, rifampicin, amphotericin B, rapamycin, gramicidin S, cyclosporin A, vancomycin, and thiostrepton) ranging in molecular weight from...
We present distorted-wave calculations and analytic fits to the dielectronic recombination (DR) rate coefficients of H-like Ne-like isosequences seven abundant astrophysical elements, including Mg, Si, S, Ar, Ca, Fe, Ni. Both ΔN = 0 (low-temperature) > (high-temperature) DR channels are included for L-shell ions. Values less ions between Mg Ni also obtained through interpolation along isosequences. Interpolation is not performed DR, since such smooth in general. Comparison made with existing...
The use of high resolution x-ray crystal spectrometers to diagnose fusion plasmas has been limited by the poor spatial localization associated with chord integrated measurements. Taking advantage a new imaging spectrometer concept [M. Bitter et al., Rev. Sci. Instrum. 75, 3660 (2004)], and improvements in detector technology [Ch. Broennimann J. Synchrotron Radiat. 13, 120 (2006)], spatially resolving built installed on Alcator C-Mod tokamak. This instrument utilizes spherically bent quartz...
Abstract We improve by a factor of 4–20 the energy accuracy strongest soft X-ray transitions Fe xvii ions resonantly exciting them in an electron beam ion trap with monochromatic at P04 beamline PETRA III synchrotron facility. By simultaneously tracking instantaneous photon-energy fluctuations high-resolution photoelectron spectrometer, we minimize systematic uncertainties down to 10–15 meV, or velocity equivalent ±∼5 km s −1 their rest energies, substantially improving our knowledge this...
We used the monochromatic soft-x-ray beamline P04 at synchrotron-radiation facility PETRA III to resonantly excite strongest $2p-3d$ transitions in neon-like Ni XIX ions, $[2p^6]_{J=0} \rightarrow [(2p^5)_{1/2}\,3d_{3/2}]_{J=1}$ and [(2p^5)_{3/2}\,3d_{5/2}]_{J=1}$, respectively dubbed 3C 3D, achieving a resolving power of 15\,000 signal-to-background ratio 30. obtain their natural linewidths, with an accuracy better than 10\%, as well oscillator-strength $f(3C)/f(3D)$ = 2.51(11) from...
The Fas receptor is one of a number important physiological inducers programmed cell death (apoptosis). Current models for regulation this process involve rapid conversion sphingomyelin to ceramide by cellular sphingomyelinases. Induced changes in levels such sphingosine-based ceramides are normally extrapolated from measurements sphingomyelinase activity or following their phosphate treatment lipid extracts with bacterial diacylglycerol kinase (DAGK). To allow direct study sphingosine- and...
We report on the observation of OVII Doppler line broadening in a compact knot at edge SN 1006 detected with Reflective Grating Spectrometer board XMM-Newton. The observed width sigma = 3.4+/-0.5 eV energy 574 indicates an oxygen temperature kT 528+/-150 keV. Combined electron 1.5 keV is direct evidence for non-equilibration high Mach number shocks, and slow subsequent equilibration. emission allows accurate determination ionization state plasma, which characterized by relatively forbidden...
We provide improved atomic calculation of wavelengths, oscillator strengths, and autoionization rates relevant to the $2\to 3$ inner-shell transitions Fe~VI--XVI, so-called Fe~M-shell unresolved transition array (UTA). A second order many-body perturbation theory is employed obtain accurate which are systematically larger than previous theoretical results by 15--45~mÅ. For a few Fe~XVI Fe~XV where laboratory measurements exist, our new wavelengths within mÅ. Using these calculations,...
The core imaging x-ray spectrometer (CIXS) is one of several ITER diagnostic systems planned for measurements the central ion and electron temperature profiles toroidal poloidal rotation velocity profiles, Ti, Te, v, vθ respectively. based on precision determinations Doppler broadening centroid shift lines highly ionized heavy impurities using a curved Bragg crystal spectral disperser imager. In departure from earlier designs, CIXS employs novel geometry utilizing spherically bent crystals...
Though MS has always appeared to be quite different from spectroscopy analytical chemists who are familiar with both, a careful examination historical and theoretical perspectives reveals striking similarity between the two. With introduction of spectral accuracy, companion concept better known mass new capabilities previously thought unfeasible can now enabled for MS. (To listen podcast about this article, please go Analytical Chemistry multimedia page at...
Optical frequency metrology in atoms and ions can probe hypothetical fifth forces between electrons neutrons by sensing minute perturbations of the electronic wave function induced them. A generalized King plot has been proposed to distinguish them from possible standard model effects arising from, e.g., finite nuclear size correlations. Additional isotopes transitions are required for this approach. Xenon is an excellent candidate, with seven stable zero spin, however it no known visible...
Using a high-resolution grating spectrometer on the Livermore EBIT-I electron beam ion trap, we have measured three n=3,4→n=1 K-shell emission lines in lithium-like O5+, which are situated near O VIII Lyman-α at 19 Å. Two of resulting wavelengths agree well with these reported earlier, but wavelength third line does not. In contrast, our new now fully those from resonant photo-absorption experiments PETRA III synchrotron facility.
Using a combined configuration interaction and many-body perturbation theory approach, we calculate the level energies of 1s22lq 1s22lq-13l' (1 ≤ q 8) complexes in iron nickel ions. Comparison with experimental results shows that calculation is accurate to within ~0.15 eV for these levels. The accuracy can be slightly worse, at ~0.5 eV. theoretical wavelengths 2→3 transitions ions are compared published measurements, discrepancies found mostly ±10 mÅ. Similar expected Such significant...
A R=44.3 m grazing-incidence grating spectrometer has been implemented on the Livermore electron beam ion traps for high-resolution measurements in soft x-ray and extreme ultraviolet region spanning from below 10 up to 50 Å. The instrument uses a with variable line spacing (about 2400 l/mm flat field of view. Spectra are recorded back-illuminated charge-coupled device detector. new greatly improves upon resolution achieved existing spectrometers complements crystal at shorter wavelengths...
A high-resolution flat-crystal spectrometer was used on the SuperEBIT electron beam ion trap to measure energies of $2{s}_{1/2}\ensuremath{-}2{p}_{3/2}$ transitions in lithiumlike through fluorinelike tungsten. These are strongly affected by energy shifts due quantum electrodynamics (QED). run at an $103.2\ifmmode\pm\else\textpm\fi{}0.5\text{ }\text{keV}$ and current 150 mA generate respective charge states; hydrogenlike aluminum neonlike krypton were as calibration elements. The spectra...
The utilization of tungsten spectroscopy for diagnostics magnetically confined fusion plasmas requires the radiative properties ions to be accurately known. At Lawrence Livermore National Laboratory, a program gather spectroscopic data on has been initiated with purpose study spectral signatures and identify candidate plasma diagnostics. In this paper, an overview recent results from WOLFRAM project is presented, which includes experimental investigations at EBIT-I SuperEBIT electron beam...
One of the most enduring and intensively studied problems x-ray astronomy is disagreement state-of-the art theory observations for intensity ratio two Fe XVII transitions crucial value plasma diagnostics, dubbed 3C 3D. We unravel this conundrum at PETRA III synchrotron facility by increasing resolving power 2.5 times signal-to-noise thousandfold compared with our previous work. The Lorentzian wings had hitherto been indistinguishable from background were thus not modeled, resulting in a...
Spectroscopic measurements of dense plasmas at billions atmospheres provide tests to our fundamental understanding how matter behaves extreme conditions. Developing reliable atomic physics models these conditions, benchmarked by experimental data, is crucial an improved radiation transport in both stars and inertial fusion targets. However, detailed spectroscopic conditions are rare, traditional collisional-radiative equilibrium models, based on isolated-atom calculations ad hoc continuum...
A new tandem mass spectrometer of the quadrupole-acceleration lens-deceleration. lens-quadrupole (QADQ) configuration is described. The instrument designed for neutralization-reionization studies and consists a 2000-u quadrupole analyzer as MS-I, an acceleration electrostatic lens, series three differentially pumped collision cells, deceleration energy filter, another MS-II. ion optical system achieves high total transmission 5–9-keV ions. Unit resolution in spectra aromatic compounds...
The intensity ratios of the 3s → 2p and 3d lines in Fe XVII were measured on Livermore electron beam ion trap employing a complementary set spectrometers, including high-resolution crystal spectrometer Goddard 32 pixel calorimeter. resulting laboratory data are agreement with satellite measurements Sun astrophysical sources collisional equilibrium such as Capella, Procyon, NGC 4636. results disagree earlier assertions that processes not accounted for must play role formation spectra solar plasmas.