IPG Photonics

About: IPG Photonics is a based out in . It is known for research contribution in the topics: Laser & Fiber laser. The organization has 903 authors who have published 1241 publications receiving 63339 citations.

Spectroscopic control of iron oxide dissolution in two ferralitic soils

Abstract: Summary Second derivative diffuse reflectance spectroscopy (DRS) in the visible range has been used to characterize changes in colour and identify the nature of Fe oxides which withstand reduction during experimental yellowing of reddish materials. It is accepted that haematite dissolves preferentially and faster than goethite, and Al-substitution controls the dissolution kinetics of Fe oxides. However, DRS has shown that haematite is more resistant than predicted and that some Fe-oxides, probably trapped within kaolinite particles, are inaccessible to solvents. DRS allows the nature of dissolved phases at each deferration step to be determined and changes in Al-content of residual phases throughout deferration to be followed. It also demonstrated that Helmholtz coordinates correlate very well with changes in Fe-oxide mineralogy and are preferable to redness ratings when monitoring differential dissolution of Fe oxides through colour measurements. DRS is a powerful and sensitive technique for monitoring the dissolution of Fe oxides in soils.

Monitoring an effusive eruption at Piton de la Fournaise using radar and thermal infrared remote sensing data: insights into the October 2010 eruption and its lava flows

Abstract: Abstract Accurate and fast delivery of information about recent lava flows is important for near-real-time monitoring of eruptions. Here, we have characterized the October 2010 lava flow at Piton de la Fournaise using various InSAR datasets. We first produced a map of the area covered by the lava flow (i.e. Arealava=0.71–0.75 km2) using the coherence of two syn-eruptive interferograms. Then we analysed two post-eruptive InSAR datasets (i.e. monostatic and bistatic data). The monostatic database provided us simultaneously with the displacement rates, lava thickness, volume and volume flux. We found that the lava flow was subsiding and moving eastward at maximum rates of 13±0.3 and 4±0.2 cm a−1, respectively. Also, it had a mean thickness of Zmean=5.85 m, VolDRE=1.77±0.75×106 m3 (1σ) and MOR=1.25±0.53 m3 s−1. The bistatic database provided us only with the thickness and volume information (i.e. Zmean=6.00 m, VolDRE=1.83±0.65×106 m3 and MOR=1.29±0.46 m3 s−1). Finally, we used a thermal remote sensing technique to verify the InSAR-derived measurements. Results show that the monostatic and bistatic datasets were both well within the range for the DRE volume obtained from MODIS data (2.44–4.40×106 m3). Supplementary material: Tables A1 and A2 give satellite images used in this study. Table A3 gives the parameters used for the calculation of the effusion rates. The figures give the data processing of the post-eruptive radar images. These are available at https://doi.org/10.6084/m9.figshare.c.2213563

Hazard implications of small-scale edifice instability and sector collapse: a case history from Soufrière Hills Volcano, Montserrat

Abstract: During the 1995 to 1998 phase of dome growth at Soufriere Hills Volcano on Montserrat, we documented instability of the steep southern rim of English9s Crater, known as Galway9s Wall. The horseshoe-shaped English9s Crater provided good evidence for previous sector collapses, and assessments undertaken in late 1996 anticipated the possibility of a partial sector collapse and a SW-directed explosion, hazards previously unrecognized on Montserrat. A change from predominantly endogenous to exogenous growth of the lava dome at the end of 1996 eased the stress on the southern sector. However, rapid dome growth in November and December 1997 led to severe reloading and eventual sector failure at the base of the buried Galway9s Wall and in the adjacent hot-spring area. This failure resulted in the debris avalanche and lateral blast of 26 December 1997. Similar sector collapses at a number of small volcanoes in the Caribbean, as well as worldwide, are evidence that edifice instability develops commonly in dome-forming eruptions. The hazards from a sector collapse and a consequent lateral blast are extreme, and monitoring operations and disaster planning at such volcanoes should focus on these, as well as on the more common hazards of conventional pyroclastic flows associated with dome growth.

High Precision Hf‐W Isotopic Measurements in Meteoritic Material Using Negative Thermal Ionisation Mass Spectrometry (NTIMS)

Abstract: This paper presents a two-stage anion-exchange procedure for tungsten extraction, an improved mass spectrometric procedure for tungsten analysis and a simplified chemical separation and TIMS procedure for the determination of Hf concentrations. The chemical separation of tungsten is based on its complexing properties with HF and H2O2. The blank level for a sample size of 300 mg is about 80 pg for tungsten. The procedure is designed for the high sensitivity of negative thermal ionisation mass spectrometry (NTIMS) provided by the use of Mg oxide as an emitter on Ir filaments. Tungsten can be readily measured with a high precision in various meteoritical material and especially in small W-poor silicate fractions. Samples containing as little as a few ng g-1 tungsten can be analysed reliably with this method. Cet article presente une procedure ďextraction du tungstene en deux etapes sur resine echangeuse ďanions, une procedure amelioree de spectrometrie de masse pour ľanalyse du tungstene, et une separation chimique simplifiee ainsi qu'une methode ďanalyse par TIMS pour determiner les concentrations en Hf. La separation du tungstene est basee sur ses proprietes complexantes vis-a-vis de HF et H2O2. Le blanc de procedure pour des echantillons de 300 mg est de 80 pg de tungstene environ. La procedure est optimisee pour beneficier de la grande sensibilite de la spectrometrie de masse a thermo-ionisation negative (NTIMS) resultant de ľutilisation ďun activateur a base ďoxyde de magnesium sur un filament ďiridium. Le tungstene peut ainsi etre mesure avec une grande precision dans divers materiaux meteoritiques et en particulier dans de petites fractions silicatees pauvres en W. Des echantillons contenant seulement quelques ng g-1 de tungstene peuvent etre analyses de facon fiable avec cette methode.