scholarly journals Polygenic chamosite from a hydrothermalized oolitic ironstone (Saint-Aubin-des-Châteaux, Armorican Massif, France): crystal chemistry, visible–near-infrared spectroscopy (red variety) and geochemical significance

Clay Minerals ◽  
2020 ◽  
Vol 55 (1) ◽  
pp. 83-95 ◽  
Author(s):  
Yves Moëlo ◽  
Emmanuel Fritsch ◽  
Eric Gloaguen ◽  
Olivier Rouer
Keyword(s):  
Near Infrared ◽  
Vanadium Content ◽  
Published Data ◽  
Octahedral Sheet ◽  
New Variety ◽  
Intervalence Charge Transfer ◽  
Geochemical Significance ◽  
Red Variety ◽  
Armorican Massif ◽  
Oolitic Ironstone

AbstractSeveral generations of chamosite, including a red variety, occur in the Ordovician hydrothermalized oolitic ironstone from Saint-Aubin-des-Châteaux (Armorican Massif, France). Their chemical re-examination indicates a low Mg content (0.925 < Fe/(Fe + Mg) < 0.954), but a significant variation in IVAl. Minor vanadium is present at up to 1.1 wt.% oxide. Variations in IVAl, the vanadium content and the colour of chamosite are related to the hydrothermal reworking of the ironstone. Taking into account other published data, the ideal composition of chamosite is (Fe5–xAl1+x)(Si3–xAl1+x)O10(OH)8, with 0.2 < x < 0.8 (0.2: equilibrium with quartz; 0.8: SiO2 deficit). The red chamosite (IIb polytype) has a mean composition of (Fe3.87Mg0.23Mn0.01□0.07Al1.74V0.07)(Si2.33Al1.67)O10(OH)8. This chamosite is strongly pleochroic, from pale yellow (E || (001)) to deep orange red (E ⊥ (001)). Visible–near-infrared absorbance spectra show a specific absorption band centred at ~550 nm for E ⊥ (001), due to a proposed new variety of Fe/V intervalence charge-transfer mechanism in the octahedral sheet, possibly Fe2+ – V4+ → Fe3+ – V3+. While the formation of green chamosite varieties is controlled by reducing conditions due to the presence of organic matter as a buffer, that of red chamosite would indicate locally a weak increase of fO2 related to oxidizing hydrothermal solutions.

Combined Near-infrared and X-ray Diffraction Investigation of the Octahedral Sheet Composition of Palygorskite

2007 ◽  
Vol 55 (6) ◽  
pp. 543-553 ◽  
Author(s):  
Vassilis Gionis ◽  
George H. Kacandes ◽  
Ioannis D Kastritis ◽  
Georgios D. Chryssikos
Keyword(s):  
Near Infrared ◽  
X Ray Diffraction ◽  
Octahedral Sheet ◽  
X Ray

scholarly journals Exploiting exciton coupling of ligand radical intervalence charge transfer transitions to tune NIR absorption

2018 ◽  
Vol 9 (6) ◽  
pp. 1610-1620 ◽  
Author(s):  
Ryan M. Clarke ◽  
Tiffany Jeen ◽  
Serena Rigo ◽  
John R. Thompson ◽  
Loren G. Kaake ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Rational Design ◽  
Near Infrared ◽  
Relative Orientation ◽  
Exciton Coupling ◽  
Salen Complexes ◽  
Nir Absorption ◽  
Charge Transfer Transitions ◽  
Intervalence Charge Transfer

We detail the rational design of a series of bimetallic bis-ligand radical Ni salen complexes in which the relative orientation of the ligand radical chromophores provides a mechanism to tune the energy of intense intervalence charge transfer (IVCT) bands in the near infrared (NIR) region.

SCANDIUM MINERALOGY: PRETULITE WITH SCANDIAN ZIRCON AND XENOTIME-(Y) WITHIN AN APATITE-RICH OOLITIC IRONSTONE FROM SAINT-AUBIN-DES-CHATEAUX, ARMORICAN MASSIF, FRANCE

2002 ◽  
Vol 40 (6) ◽  
pp. 1657-1673 ◽  
Author(s):  
Y. Moelo ◽  
Y. Lulzac ◽  
O. Rouer ◽  
P. Palvadeau ◽  
E. Gloaguen ◽  
...  
Keyword(s):  
Armorican Massif ◽  
Oolitic Ironstone

scholarly journals Assessing Trees, Wood and Derived Products with near Infrared Spectroscopy: Hints and Tips

2016 ◽  
Vol 24 (6) ◽  
pp. 485-505 ◽  
Author(s):  
Jakub Sandak ◽  
Anna Sandak ◽  
Roger Meder
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Early Career ◽  
Wood Products ◽  
Published Data ◽  
Genetic Traits ◽  
Vast Number

Wood is a renewable and valuable resource for a variety of end-use application areas. However, rapid and reliable assessments are needed to identify the quality of the tree, timber or wood product at all stages of production and processing. The ideal technology for assessing wood and wood products must provide reliable data, be user-friendly, cost-competitive and provide a rapid analysis. The ultimate application of near infrared (NIR) spectroscopy of wood or wood products is to substitute for costly and time-consuming reference measurements in order to aid process optimisation or determine properties and genetic traits on large numbers of individual samples. Increased interest in the application of NIR spectroscopy in various research fields including wood is observed nowadays. A vast number of publications highlight the potential of NIR spectroscopy for the characterisation of wood in a broad area of uses. The Journal of Near Infrared Spectroscopy has published two special issues on the application of NIR to forestry and wood research in 2010 and 2011 and a recent literature search yielded in excess of 556,000 results which can be easily found by using the search terms “NIR” and “wood”. This mass of published data may suggest that the technique of NIR spectroscopy is widely understood and broadly adopted by the timber industry, but even in recent papers it is evident that there is still a need to better understand the fundamental issues regarding sample selection and preparation, instrument choice, correct measurement and spectral interpretation. In this paper we draw on more than 40 years of collective experience and summarise state-of-the-art knowledge regarding instrumentation, spectral acquisition and data mining in regard to wood science and technology. The goal of this tutorial is two-fold: first, to inform early career wood scientists of the critical steps in utilising NIR spectroscopy to assess the quality of wood. Second, to alert managers to the level of operator skill required for the successful adoption of NIR technology. Some basic information is presented here, but due to the limited size of the manuscript, reference to more specific and detailed literature is provided in each section.

scholarly journals Cerebral and Muscle Tissue Oxygenation During Incremental Cycling in Male Adolescents Measured by Time-Resolved Near-Infrared Spectroscopy

2016 ◽  
Vol 28 (2) ◽  
pp. 275-285 ◽  
Author(s):  
Goutham Ganesan ◽  
Szu-yun Leu ◽  
Albert Cerussi ◽  
Bruce Tromberg ◽  
Dan M. Cooper ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Continuous Wave ◽  
Ventilatory Threshold ◽  
Published Data ◽  
Peak Time ◽  
Time Resolved ◽  
Tissue Specific ◽  
Threshold Phenomena

Near-infrared spectroscopy has long been used to measure tissue-specific O2 dynamics in exercise, but most published data have used continuous wave devices incapable of quantifying absolute Hemoglobin (Hb) concentrations. We used time-resolved near-infrared spectroscopy to study exercising muscle (Vastus Lateralis, VL) and prefrontal cortex (PFC) Hb oxygenation in 11 young males (15.3 ± 2.1 yrs) performing incremental cycling until exhaustion (peak VO2 = 42.7 ± 6.1 ml/min/kg, mean peak power = 181 ± 38 W). Time-resolved near-infrared spectroscopy measurements of reduced scattering (µs´) and absorption (µa) at three wavelengths (759, 796, and 833 nm) were used to calculate concentrations of oxyHb ([HbO2]), deoxy Hb ([HbR]), total Hb ([THb]), and O2 saturation (stO2). In PFC, significant increases were observed in both [HbO2] and [HbR] during intense exercise. PFC stO2% remained stable until 80% of total exercise time, then dropped (−2.95%, p = .0064). In VL, stO2% decreased until peak time (−6.8%, p = .01). Segmented linear regression identified thresholds for PFC [HbO2], [HbR], VL [THb]. There was a strong correlation between timing of second ventilatory threshold and decline in PFC [HbO2] (r = .84). These findings show that time-resolved near-infrared spectroscopy can be used to study physiological threshold phenomena in children during maximal exercise, providing insight into tissue specific hemodynamics and metabolism.

UV-vis/X-ray/thermo-induced synthesis and UV–SWIR photoresponsive property of a mixed-valence viologen molybdate semiconductor

2021 ◽  
Author(s):  
Peng-Hao Wang ◽  
Cao-Ming Yu ◽  
Xiao-Qing Yu ◽  
Ming-Sheng Wang ◽  
Guo-Cong Guo
Keyword(s):  
Charge Transfer ◽  
Radical Cation ◽  
Near Infrared ◽  
Mixed Valence ◽  
Design Strategy ◽  
X Ray ◽  
Intervalence Charge Transfer

A new design strategy through synergy of Mo (VI)–Mo (V) intervalence charge transfer and π(radical)–π(radical/cation) interactions is proposed to obtain semiconductors with photoresponsive ranges covering the whole UV–SWIR (ultraviolet–shortwave near-infrared;...

scholarly journals Palaeozoic oolitic ironstone of the French Armorican Massif: a chemical and structural trap for orogenic base metal–As–Sb–Au mineralisation during Hercynian strike-slip deformation

2007 ◽  
Vol 42 (4) ◽  
pp. 399-422 ◽  
Author(s):  
Eric Gloaguen ◽  
Yannick Branquet ◽  
Philippe Boulvais ◽  
Yves Moëlo ◽  
Jean-Jacques Chauvel ◽  
...  
Keyword(s):  
Base Metal ◽  
Strike Slip ◽  
Structural Trap ◽  
Slip Deformation ◽  
Armorican Massif ◽  
Oolitic Ironstone
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