Search results for "scattering"
showing 10 items of 8332 documents
Light-Scattering and -Absorption of Nanoparticles
2012
To understand the optical response of nanoparticles to the incident light, a theoretical description is needed, which is given in this chapter. In a first approximation, these optical properties can be described using a quasi-static model, which assumes a particle-size much smaller than the wavelength of the light. The derivation of the polarizability of a sphere, which describes its optical properties, and further extensions for spheroidal, rod-shaped and coated particles are given in Sect. 2.2.
Remitted photon path length in human skin, skin phantoms and cell cultures
2020
An experimental method for remitted photon path length measurements in scattering media has been developed and tested on human skin and skin neoplasms, skin phantoms and cell cultures. The photon time-of-flight (PTOF) measurement method was used in this study, where the photon travel time was converted into path length. Remitted light signals were obtained using a picosecond broadband laser and a set of narrowband interference filters in spectral rang 520 – 760 nm. Five different distances of 1, 8, 12, 16 and 20 mm between the source and detector fibers were used. Measurements were performed at different wavelengths and distance combinations; they were taken from human skin and skin malform…
Structure of longitudinal chromomagnetic fields in high energy collisions
2014
We compute expectation values of spatial Wilson loops in the forward light cone of high-energy collisions. We consider ensembles of gauge field configurations generated from a classical Gaussian effective action as well as solutions of high-energy renormalization group evolution with fixed and running coupling. The initial fields correspond to a color field condensate exhibiting domain-like structure over distance scales of order the saturation scale. At later times universal scaling emerges at large distances for all ensembles, with a nontrivial critical exponent. Finally, we compare the results for the Wilson loop to the two-point correlator of magnetic fields.
On the discrete linear ill‐posed problems
1999
An inverse problem of photo‐acoustic spectroscopy of semiconductors is investigated. The main problem is formulated as the integral equation of the first kind. Two different regularization methods are applied, the algorithms for defining regularization parameters are given. Diskrečiųjų blogai sąlygotų uždavinių klausimu Santrauka Darbe nagrinejamas foto‐akustines spektroskopijos puslaidininkiuose uždavinys, kuriame i vertinami nešeju difuzijos ir rekombinacijos procesai. Reikia atstatyti šaltinio funkcija f(x), jei žinoma antrosios eiles difuzijos lygtis ir atitinkamos kraštines salygos. Naudojantis matavimu, atliktu ivairiuose dažniuose, rezultatais sprendžiamas atvirkštinis uždavinys, kel…
Resolution of the ATLAS muon spectrometer monitored drift tubes in LHC Run 2
2019
The momentum measurement capability of the ATLAS muon spectrometer relies fundamentally on the intrinsic single-hit spatial resolution of the monitored drift tube precision tracking chambers. Optimal resolution is achieved with a dedicated calibration program that addresses the specific operating conditions of the 354 000 high-pressure drift tubes in the spectrometer. The calibrations consist of a set of timing offsets and drift time to drift distance transfer relations, and result in chamber resolution functions. This paper describes novel algorithms to obtain precision calibrations from data collected by ATLAS in LHC Run 2 and from a gas monitoring chamber, deployed in a dedicated gas fac…
Bio-inspired consolidants derived from crystalline nanocellulose for decayed wood
2018
Abstract Novel bio-inspired materials derived from crystalline nanocellulose (CNC) have been tested as wood consolidants. A suspension of CNC, produced by acid hydrolysis of cellulose and used as such or mixed with lignin and/or siloxane derivatives (PDMS), was applied on rotted wood samples of Norway spruce. X-Ray diffraction analysis on CNC powder showed high crystallinity index. Dynamic light scattering (DLS) measurement indicated a nearly uniform particle size distribution with an average hydrodynamic diameter for pure CNC smaller than that in the mixtures. Raman and FTIR spectroscopies suggested interactions between lignin, PDMS and CNC components. The storage modulus of wood samples, …
Chemical Interface Damping Depends on Electrons Reaching the Surface.
2017
Metallic nanoparticles show extraordinary strong light absorption near their plasmon resonance, orders of magnitude larger compared to nonmetallic nanoparticles. This "antenna" effect has recently been exploited to transfer electrons into empty states of an attached material, for example to create electric currents in photovoltaic devices or to induce chemical reactions. It is generally assumed that plasmons decay into hot electrons, which then transfer to the attached material. Ultrafast electron-electron scattering reduces the lifetime of hot electrons drastically in metals and therefore strongly limits the efficiency of plasmon induced hot electron transfer. However, recent work has revi…
Application of small angle neutron scattering to micellar fluids
1990
Abstract In this paper we present a short overview of the application of small angle neutron scattering (SANS) to micellar fluids. In the first part of the paper a general expression of the scattering equation is derived, with particular emphasis on the approximations involved and on their practical consequences. In the second part of the paper we present six selected test cases (such as mono- and polydisperse fluids, critical fluids, shapes other than spherical, etc.) taken from our own work, to demonstrate the kind of analysis performed in each case to extract the information from SANS data.
Thermodynamical aspects regarding the formation of self-assembly decylpolyglucoside structures
2005
In this study, we used a generalized form of a recently reported parametrization based on the differential geometry and the thermodynamics of dispersed systems to ascertain the capability of decylpolyglucoside alone or in association with cholesterol to form vesicle structures (niosomes). The theoretical calculation of the energy balance involved in the vesicles formation was carried out using values of the critical concentration of formation (ccf), surface tension and the molar surface area of the non-ionic surfactant. Furthermore, in order to confirm the theoretical results found in this work, we prepared and characterized vesicles made with decylpolyglucoside and cholesterol. The vesicle…
Simplified Modeling of Radiant Fields in Heterogeneous Photoreactors. 2. Limiting “Two-Flux” Model for the Case of Reflectance Greater Than Zero
1997
In the first part of this work a simple model for the description of the radiant field in heterogeneous photoreactors was developed, based on the assumption of zero reflectance of the particles. In this second part of the investigation a limiting model is developed in which the above hypothesis is removed. In this last model, scattering phenomena are dealt with in a very simple “two-flux” way, so that analytical solutions are obtained again. The case here developed is the same as in part 1, namely slab geometry with orthogonal parallel irradiation, giving special reference to the important case of semi-infinite reactor thickness. Both cases of solid catalysts with single particle size and w…