Search results for " absorption"

Model, software and database for line-mixing effects in the ν3 and ν4 bands of CH4 and tests using laboratory and planetary measurements-I: N2(and ai…

2006

International audience; Absorption spectra of the infrared ν3 and ν4 bands of CH4 perturbed by N2 over large ranges of pressure and temperature have been measured in the laboratory. A theoretical approach accounting for line mixing is proposed to (successfully) model these experiments. It is similar to that of Pieroni et al. [J Chem Phys 1999;110:7717–32] and is based on state-to-state rotational cross-sections calculated with a semi-classical approach and a few empirical parameters. The latter, which enable switching from the state space to the line space, are deduced from a fit of a single room temperature spectrum of the ν3 band at 50 atm. The comparisons between numerous measured and ca…

Effect of Training-Induced Changes in Achilles Tendon Stiffness on Muscle–Tendon Behavior During Landing

2018

During rapid deceleration of the body, tendons buffer part of the elongation of the muscle–tendon unit (MTU), enabling safe energy dissipation via eccentric muscle contraction. Yet, the influence of changes in tendon stiffness within the physiological range upon these lengthening contractions is unknown. This study aimed to examine the effect of training-induced stiffening of the Achilles tendon on triceps surae muscle–tendon behavior during a landing task. Twenty-one male subjects were assigned to either a 10-week resistance-training program consisting of single-leg isometric plantarflexion (n = 11) or to a non-training control group (n = 10). Before and after the training period, plantarf…

Third order nonlinear optical properties of novel TetrathiafulvalenePhenanthroline based dyads

2011

The non-linear optical properties of π-conjugated organic molecules such as TTF and their derivatives have recently gained particular interest due to their extended π-system and the strong electron donating character. The knowledge of the nonlinear optical response, as well as the impact of the charge transfer on the nonlinearity is very important. As such systems can be used in a variety of applications. In this study we investigate the nonlinear absorption of novel tetrathiafulvalene-phenanthroline based dyads by means of the Z-scan technique.

Predicting tire/pavement noise impact reduction using numerical simulation and experimental data for open graded asphalt mixture

2013

The environmental impact of noise from roads and highways traffic is relevant in urban and rural areas. The use of open-graded asphalt pavements reduces significantly the noise, entrapping the acoustic waves inside the porous structure of the material. In this paper we propose a simulation approach in order to predict the acoustic properties of the asphalt mixture from geometrical and topological indicators. In detail we have generated, using a Random Sequential Adsorption model, synthetic samples starting from the same grading and bitumen contents of real samples manufactured in laboratory. We have measured the acoustic adsorption coefficient of the real samples and we have investigated th…

Copper Induces a Core Plasmon in Intermetallic Au(144,145)–xCux(SR)60 Nanoclusters

2015

The electronic structure and optical absorption spectra of intermetallic thiol-stabilized gold-copper clusters, having 144-145 metal atoms and 60 thiols, were studied by ab initio computations. The widely known icosahedral-based cluster model from the work of Lopez-Acevedo et al. (2009) was used, and clusters doped with one to 30 copper atoms were considered. When doped inside the metal core, copper induces dramatic changes in the optical spectrum as compared to the previously studied all-gold Au144(SR)60. An intense broad absorption peak develops in the range 535-587 nm depending on the amount of doping and doping sites. This result agrees very well with recent experiments by the Dass grou…

Single Crystal Sub‐Nanometer Sized Cu6(SR)6 Clusters: Structure, Photophysical Properties, and Electrochemical Sensing

2016

Organic ligand-protected metal nanoclusters have attracted extensively attention owing to their atomically precise composition, determined atom-packing structure and the fascinating properties and promising applications. To date, most research has been focused on thiol-stabilized gold and silver nanoclusters and their single crystal structures. Here the single crystal copper nanocluster species (Cu6(SC7H4NO)6) determined by X-ray crystallography and mass spectrometry is presented. The hexanuclear copper core is a distorted octahedron surrounded by six mercaptobenzoxazole ligands as protecting units through a simple bridging bonding motif. Density functional theory (DFT) calculations provide…

Optical Absorption of Excimer Laser‐Induced Dichlorine Monoxide in Silica Glass and Excitation of Singlet Oxygen Luminescence by Energy Transfer from…

2021

An optical absorption (OA) band of interstitial dichlorine monoxide molecules with peak at 4.7 eV and halfwidth 0.94 eV is identified in F2 laser - irradiated (photon energy=7.9 eV) synthetic silica glass bearing both interstitial O2 and Cl2 molecules. Alongside with intrinsic defects, this OA band can contribute to solarization of silica glasses produced from SiCl4. While the formation of ClClO is confirmed by its Raman signature, its structural isomer ClOCl may also contribute to this induced OA band. Thermal destruction of this band between 300C and 400C almost completely restores the pre-irradiation concentration of interstitial Cl2. An additional weak OA band at 3.5 eV is tentatively a…

Radiation effects on antimonium-doped Yb-fibers

2013

Etude spectroscopique de fibres durcies pour un environnement radiatif sévère

2013

Les nouveaux environnements radiatifs, comme LMJ, ITER, ILE/ELI, HiPER, réacteurs nucléaires des générations III+ et IV, nécessitent le développement de nouveaux composants pour le transport et le traitement des signaux. A cause de l’impossibilité d’utiliser les composants électroniques, la recherche est orientée vers les composants à fibres optiques comme vecteur d’information et aussi comme élément de diagnostic. Ils présentent de nombreux avantages, comme leur relative immunité électromagnétique, faible pois, large bande passante, mais les rayonnements gamma et les neutrons dégradent leur transmission. La dégradation dépend principalement de la composition de la fibre. Ainsi, il a été mo…

Origins of radiation-induced attenuation in pure-silica-core and Ge-doped optical fibers under pulsed x-ray irradiation

2020

We investigated the nature, optical properties, and decay kinetics of point defects causing large transient attenuation increase observed in silica-based optical fibers exposed to short duration and high-dose rate x-ray pulses. The transient radiation-induced attenuation (RIA) spectra of pure-silica-core (PSC), Ge-doped, F-doped, and Ge + F-doped optical fibers (OFs) were acquired after the ionizing pulse in the spectral range of [∼0.8–∼3.2] eV (∼1500–∼380 nm), from a few ms to several minutes after the pulse, at both room temperature (RT) and liquid nitrogen temperature (LNT). Comparing the fiber behavior at both temperatures better highlights the thermally unstable point defects contribut…