53 research outputs found
Precision measurement of the isotopic shift in calcium ions using photon recoil spectroscopy
[no abstract
Efficient sympathetic motional ground-state cooling of a molecular ion
Cold molecular ions are promising candidates in various fields ranging from
precision spectroscopy and test of fundamental physics to ultra-cold chemistry.
Control of internal and external degrees of freedom is a prerequisite for many
of these applications. Motional ground state cooling represents the starting
point for quantum logic-assisted internal state preparation, detection, and
spectroscopy protocols. Robust and fast cooling is crucial to maximize the
fraction of time available for the actual experiment. We optimize the cooling
rate of ground state cooling schemes for single ions and
sympathetic ground state cooling of . In particular, we
show that robust cooling is achieved by combining pulsed Raman sideband cooling
with continuous quench cooling. Furthermore, we experimentally demonstrate an
efficient strategy for ground state cooling outside the Lamb-Dicke regime.Comment: 11 pages, 11 figure
Precision isotope shift measurements in Ca using highly sensitive detection schemes
We demonstrate an efficient high-precision optical spectroscopy technique for
single trapped ions with non-closed transitions. In a double-shelving
technique, the absorption of a single photon is first amplified to several
phonons of a normal motional mode shared with a co-trapped cooling ion of a
different species, before being further amplified to thousands of fluorescence
photons emitted by the cooling ion using the standard electron shelving
technique. We employ this extension of the photon recoil spectroscopy technique
to perform the first high precision absolute frequency measurement of the
D P transition in Ca,
resulting in a transition frequency of kHz.
Furthermore, we determine the isotope shift of this transition and the
S P transition for Ca,
Ca and Ca ions relative to Ca with an
accuracy below 100 kHz. Improved field and mass shift constants of these
transitions as well as changes in mean square nuclear charge radii are
extracted from this high resolution data
Compact setup for standoff laser induced breakdown spectroscopy of radioactive material
Radioactive materials present a major threat and can cause severe direct and long term injuries to humans as experienced i.e. in the
Fukushima and Chernobyl nuclear plant catastrophes. Furthermore, intended use of radiological dispersal devices may spread
radioactive materials over large areas. Detecting these hazards and investigating the status of contaminated areas a remote standoff
determination of nuclear fission products would serve as a helpful tool for first responders and damage control teams. Laser induced
breakdown spectroscopy (LIBS) offers a unique possibility for the identification of nuclear fission products and can be able to
distinguish different isotopes of the same species. Within this scope and based on experiences with a high power / long distance (>
100 m) LIBS setup a compact and low power setup is presented. The compactness allows for handheld operation as well as mounted
on a small robot or on an unmanned aerial vehicle (UAV) an advanced setup could be controlled remotely and would be able to
safely determine radioactive materials
Precision spectroscopy by photon-recoil signal amplification
Precision spectroscopy of atomic and molecular ions offers a window to new
physics, but is typically limited to species with a cycling transition for
laser cooling and detection. Quantum logic spectroscopy has overcome this
limitation for species with long-lived excited states. Here, we extend quantum
logic spectroscopy to fast, dipole-allowed transitions and apply it to perform
an absolute frequency measurement. We detect the absorption of photons by the
spectroscopically investigated ion through the photon recoil imparted on a
co-trapped ion of a different species, on which we can perform efficient
quantum logic detection techniques. This amplifies the recoil signal from a few
absorbed photons to thousands of fluorescence photons. We resolve the line
center of a dipole-allowed transition in 40Ca+ to 1/300 of its observed
linewidth, rendering this measurement one of the most accurate of a broad
transition. The simplicity and versatility of this approach enables
spectroscopy of many previously inaccessible species.Comment: 25 pages, 6 figures, 1 table, updated supplementary information,
fixed typo
Quantitative determination of hazardous substances in aerosols by light scattering and machine learning with the example of Cr(VI) in electroplating processes
Regulations of safety usage of hazardous substances impose companies to monitor their emissions. A novel approach is presented to determine the mass concentration of Cr(VI) in exhaust air based on angular light scattering combined with machine learning algorithm
Compact setup for standoff Laser induced breakdown spectroscopy of radioactive materials
Radioactive materials present a major threat and can cause severe direct and long term injuries to humans as experienced i.e. in the Fukushima and Chernobyl nuclear plant catastrophes. Furthermore, intended use of radiological dispersal devices can be used to spread radioactive materials over large areas. Detecting these hazards and investigating the status of contaminated areas a remote standoff determination of nuclear fission products would serve as a helpful tool for first responders and damage control teams. Laser induced breakdown spectroscopy (LIBS) offers a unique possibility for the identification of elements as nuclear fission products and is even able to distinguish different isotopes of the same species. Within this scope and based on experiences with a high power / long distance (> 100 m) LIBS setup we present a new compact and low power setup. The compactness allows for handheld operation as well as mounted on a small robot or on an unmanned aerial vehicle (UAV) an advanced setup could be controlled remotely and would be able to safely determine radioactive materials
Corrigendum: Detection of motional ground state population using delayed pulses (2016 New J. Phys. 18 013037)
[No abstract available
Nickel sulfide nanocrystals on nitrogen-doped porous carbon nanotubes with high-efficiency electrocatalysis for room-temperature sodium-sulfur batteries
Polysulfide dissolution and slow electrochemical kinetics of conversion reactions lead to low utilization of sulfur cathodes that inhibits further development of room-temperature sodium-sulfur batteries. Here we report a multifunctional sulfur host, NiS2 nanocrystals implanted in nitrogen-doped porous carbon nanotubes, which is rationally designed to achieve high polysulfide immobilization and conversion. Attributable to the synergetic effect of physical confinement and chemical bonding, the high electronic conductivity of the matrix, closed porous structure, and polarized additives of the multifunctional sulfur host effectively immobilize polysulfides. Significantly, the electrocatalytic behaviors of the Lewis base matrix and the NiS2 component are clearly evidenced by operando synchrotron X-ray diffraction and density functional theory with strong adsorption of polysulfides and high conversion of soluble polysulfides into insoluble Na2S2/Na2S. Thus, the as-obtained sulfur cathodes exhibit excellent performance in room-temperature Na/S batteries
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