In this review, we present person-transportable laser induced breakdown spectroscopy (LIBS) devices that have previously been developed and reported in the literature as well as their applications. ...They are compared with X-ray fluorescent (XRF) devices, which represent their strongest competition. Although LIBS devices have advantages over XRF devices, such as sensitivity to the light elements, high spatial resolution and the possibility to distinguish between different layers of the sample, there are also disadvantages and both are discussed here. Furthermore, the essential portable LIBS instrumentation (laser, spectrograph and detector) is presented, and published results related to new laser sources (diode-pumped solid-state, microchip and fiber lasers) used in LIBS are overviewed. Compared to conventional compact flashlamp pumped solid-state lasers, the new laser sources provide higher repetition rates, higher efficiency (less power consumption) and higher beam quality, resulting in higher fluences, even for lower energies, and could potentially increase the figure of merit of portable LIBS instruments. Compact spectrometers used in portable LIBS devices and their parts (spectrograph, detector) are also discussed.
•Overview of portable LIBS devices transportable by a person•Discussion and new trends about portable LIBS instrumentation: laser, spectrograph and detector•Overview of applications of DPSS, microchip and fiber lasers in LIBS
Abstract
Superconductivity mediated by phonons is typically conventional, exhibiting a momentum-independent
s
-wave pairing function, due to the isotropic interactions between electrons and phonons ...along different crystalline directions. Here, by performing inelastic neutron scattering measurements on a superconducting single crystal of Sr
0.1
Bi
2
Se
3
, a prime candidate for realizing topological superconductivity by doping the topological insulator Bi
2
Se
3
, we find that there exist highly anisotropic phonons, with the linewidths of the acoustic phonons increasing substantially at long wavelengths, but only for those along the 001 direction. This observation indicates a large and singular electron-phonon coupling at small momenta, which we propose to give rise to the exotic
p
-wave nematic superconducting pairing in the M
x
Bi
2
Se
3
(M = Cu, Sr, Nb) superconductor family. Therefore, we show these superconductors to be example systems where electron-phonon interaction can induce more exotic superconducting pairing than the
s
-wave, consistent with the topological superconductivity.
The ammonia spectrum is revisited in the important 1.6 µm atmospheric transparency window between 5650 and 6350 cm
$ ^{-1} $
−
1
on the basis of recently recorded high-resolution Fourier transform ...spectra. These spectra offer an improved frequency sampling and better traceability of the measurement conditions compared to previously studied Kitt Peak spectra (Cacciani et al. J. Quant Spectrosc Radiat Transf 2021; 258:107334. https://doi.org/10.1016/j.jqsrt.2020.107334). Overall, 4812
$ ^{14} $
14
NH
$ _3 $
3
lines were measured in the 5650-6350 cm
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−
1
region corresponding to 4866 transitions including 2066 new ones compared with our previous study, included in the HITRAN2020 database. The energy of 1023 upper state levels (including 107 new ones) was derived from 2608 assigned transitions. Independently, ammonia spectra recorded in a supersonic jet expansion using a tunable extended cavity diode laser allow us to check the absolute transition energies in the 5980-6080 cm
$ ^{-1} $
−
1
range. Accurate jet spectra calibration was achieved using CH
$ _4 $
4
reference line positions known with kHz accuracy. The position agreement with the FTS data is within the
$ 4\times 10^{-4} $
4
×
10
−
4
cm
$ ^{-1} $
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1
uncertainty of the positions measured in the jet expansion. A recommended line list of 5620 transitions is provided for
$ ^{14} $
14
NH
$ _3 $
3
in the considered 5650-6350 cm
$ ^{-1} $
−
1
region.
Tin sulfide (SnS) is an analog of tin selenide (SnSe) and is a promising thermoelectric material. However, a stable and effective doping of this compound has still not been achieved. According to our ...observations, this is mainly due to the very low equilibrium solubility of dopants and formation of extraneous phases, which is also an important issue for photovoltaic (PV) applications. Achieving a reasonable (60%) doping efficiency of thallium (Tl) in a cation sublattice of SnSe, we explored the same doping for SnS. Hot-pressed polycrystalline (PC) samples were prepared along with their single-crystalline (SC) counterparts. Samples were examined for extraneous phases by X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS). Thermal stability was determined by thermogravimetric analysis (TGA). Measurements of the Seebeck and Hall coefficient, and electrical and thermal conductivity were conducted over a temperature range of 80–775 K. The experiments suggested a very low solubility of Tl (≈0.1%). Slight Tl doping resulted in a substantial improvement of the thermoelectric efficiency (ZT) of SnS and enhanced crystal quality in terms of carrier mobility. We found, however, that attempts to prepare material with a high concentration of Tl or the examination of samples at temperatures above 600 K led to chemical instability.
•Equilibrium solubility of thallium is close to x = 0.001 for Sn1-xTlxS crystals.•Thallium increases concentration of holes by two orders.•Thallium induces healing of the SnS structure.•Thallium doping increases mobility of free holes in SnS single crystals.•Thallium enhances thermoelectric properties of SnS.
We report high-resolution neutron scattering measurements of the low energy spin fluctuations of KFe2As2, the end member of the hole-doped Ba1−xKxFe2As2 family with only hole pockets, above and below ...its superconducting transition temperature T c (∼ 3.5 K). Our data reveal clear spin fluctuations at the incommensurate wave vector (0.5 ± δ , 0, L), (δ = 0.2) (1-Fe unit cell), which exhibit L -modulation peaking at L = 0.5 . Upon cooling to the superconducting state, the incommensurate spin fluctuations gradually open a spin gap and form a sharp spin resonance mode. The incommensurability (2 δ = 0.4) of the resonance mode (∼ 1.2 meV) is considerably larger than the previously reported value (2 δ ≈ 0.32) at higher energies (≥ ∼ 6 meV). The determination of the momentum structure of spin fluctuation in the low energy limit allows a direct comparison with the realistic Fermi surface and superconducting gap structure. Our results point to an s -wave pairing with a reversed sign between the hole pockets near the zone center in KFe2As2.
In contrast to magnetic order formed by electrons’ dipolar moments, ordering phenomena associated with higher-order multipoles (quadrupoles, octupoles, etc.) are more difficult to characterize ...because of the limited choice of experimental probes that can distinguish different multipolar moments. The heavy-fermion compoundCeB6and its La-diluted alloys are among the best-studied realizations of the long-range-ordered multipolar phases, often referred to as “hidden order.” Previously, the hidden order in phase II was identified as primary antiferroquadrupolar and field-induced octupolar order. Here, we present a combined experimental and theoretical investigation of collective excitations in phase II ofCeB6. Inelastic neutron scattering (INS) in fields up to 16.5 T reveals a new high-energy mode above 14 T in addition to the low-energy magnetic excitations. The experimental dependence of their energy on the magnitude and angle of the applied magnetic field is compared to the results of a multipolar interaction model. The magnetic excitation spectrum in a rotating field is calculated within a localized approach using the pseudospin representation for theΓ8states. We show that the rotating-field technique at fixed momentum can complement conventional INS measurements of the dispersion at a constant field and holds great promise for identifying the symmetry of multipolar order parameters and the details of intermultipolar interactions that stabilize hidden-order phases.
The warming climate of recent decades has led to further aridity of the Mongolian landscape and has had major effects on forest growth and wildfire occurrence. Here, we investigated drought and ...wildfire effects on the growth of Pinus sylvestris along an ecologically diverse transect in semiarid north-central Mongolia using two separate subsets. Tree-ring width series of the first subset, represented by trees without fire scars, were clustered into three regional chronologies reflecting environmental differences of delineated geo-vegetation zones. Tree-ring growth reflected June drought signal at all three zones. The increasing radial growth trend was found in the dark taiga zone, likely supported by permafrost summer thawing, primarily caused by temperature increases. The second subset, represented by injured trees, showed that most wildfires occurred during the dormant season and in the forest-steppe zone; April–May drought conditions substantially contributed to triggering wildfires. Nevertheless, an increased frequency of wildfires in the study area was not observed, despite temperature increases since 1940. Our study highlights the significance of the effect of the ongoing temperature increase on north-central Mongolian pine forests, and, correspondingly, the need to conserve an endangered ecosystem of the dark taiga and to undertake afforestation activities in devastated pine forests.
•We evaluate the long-term Pinus sylvestris growth in north-central Mongolia.•TRW variability reflects the tree distribution into three geo-vegetation zones.•Scots pine climate sensitivity reflects significant June drought signals at all zones.•The most drought limited pines showed a significantly decreasing growth trend.•Spring drought conditions contributed to the triggering of the wildfires.
•Doping iron interacts with native defects in SnS.•Fe-doping reveals high hole mobility in SnS.•Carrier mobility is largely insensitive to the doping process and increasing mosaicity.•The dominant ...charge carrier scattering at higher temperatures is scattering on homopolar optical phonons.
Defect control is critical to achieve long carrier lifetimes in semiconductors. SnS is a promising thermoelectric and photovoltaic material, in which native defects play a detrimental role, particularly in photovoltaics. In this study, we investigated the Fe-doping of SnS and the interaction of Fe impurities with native defects in a series of single crystals of Sn1-xFexS up to concentrations of x = 0.05. Although the doped single crystals appear rather disordered, the hole mobility is very high (∼8500 cm2V-1s−1 at 30 K for Sn0.99Fe0.01S), suggesting that hole-mediated charge transport in this material is largely insensitive to extrinsic impurities. Charge transport analysis suggests that the incorporation of Fe atoms leads to the healing of the intrinsic defect structure and the exclusion of minority electrons from charge transport, allowing the observation of high hole mobility.
Increased echogenicity of the substantia nigra is a typical transcranial sonography finding in Parkinson disease. Experimental software for digital analysis of the echogenic substantia nigra area has ...been developed. The aim of this study was to compare the evaluation of substantia nigra echogenicity by using digital analysis with a manual measurement in patients with Parkinson disease and healthy volunteers.
One hundred thirteen healthy volunteers were enrolled in the derivation cohort, and 50 healthy volunteers and 30 patients with Parkinson disease, in the validation cohort. The substantia nigra was imaged from the right and left temporal bone window by using transcranial sonography. All subjects were examined twice by using different sonographic machines by an experienced sonographer. DICOM images of the substantia nigra were encoded; then, digital analysis and manual measurement of the substantia nigra were performed. The 90th percentile of the derivation cohort values was used as a cut-point for the evaluation of the hyperechogenic substantia nigra in the validation cohort. The Spearman coefficient was used for assessment of the correlation between both measurements. The Cohen κ coefficient was used for the assessment of the correlation between both measurements and Parkinson disease diagnosis.
The Spearman coefficient between measurements by using different machines was 0.686 for digital analysis and 0.721 for manual measurement (P < .0001). Hyperechogenic substantia nigra was detected in the same 26 (86.7%) patients with Parkinson disease by using both measurements. Cohen κ coefficients for digital analysis and manual measurement were 0.787 and 0.762, respectively (P < .0001).
The present study showed comparable results when measuring the substantia nigra features conventionally and by using the developed software.
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