Search results for "Spectral"
showing 10 items of 3116 documents
Spatial and spectral properties of small area THz generation for sub-wavelength microscopy
2010
A highly localized THz source is a promising candidate for sub-wavelength microscopy, due to its superior radiation power throughput with respect to others near-field techniques. Here, we report on the spatial and the spectral near-field properties of our highly localized THz source.
1/f noise in streaming electrification
2005
The paper presents the measurement results of the noise generated by static electricity. The tests were performed in the spinning-disk system. Insulation liquid (transformer oil) was used for electrostatic charge generation. The element measured was the current flowing to the disk surface. A stochastic term is present in the current. Existance of this term is due to the complex chemical constitution of the oil. A relaxation of the polar molecules has inertial character. The spreading of a large amount of the relaxation phenomena can lead to forming a compounded spectrum close in shape to 1/f noise. Power spectral density of the polarization was defined for periodic step function. The calcul…
Understanding the2pcore-level spectra of manganese: Photoelectron spectroscopy experiments and Anderson impurity model calculations
2007
Using high-resolution core-level photoelectron spectroscopy and modified Anderson impurity model calculations, we study the $\mathrm{Mn}\phantom{\rule{0.2em}{0ex}}2p$ spectrum of manganese metal and resolve the current debate about its spectral shape. An unusual satellite feature, $1\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ from the main peak, is observed in the $\mathrm{Mn}\phantom{\rule{0.2em}{0ex}}2{p}_{3∕2}$ spectrum of a thick Mn layer grown on Al. It originates from intra-atomic multiplet effect related to Mn atoms with large local moment. The satellite decreases in intensity for thin Mn layers and for Al deposition on bulklike Mn because of enhanced $\mathrm{Mn}\phantom{\rule{0.2em}{0e…
Optically detected magnetic resonances of nitrogen-vacancy ensembles inC13-enriched diamond
2016
We present an experimental and theoretical study of the optically detected magnetic resonance signals for ensembles of negatively charged nitrogen-vacancy (NV) centers in a $^{13}\mathrm{C}$ isotopically enriched single-crystal diamond. We observe four broad transition peaks with superimposed sharp features at zero magnetic field and study their dependence on an applied magnetic field. A theoretical model that reproduces all qualitative features of these spectra is developed. Understanding the magnetic-resonance spectra of NV centers in an isotopically enriched diamond is important for emerging applications in nuclear magnetic resonance.
Small angle neutron scattering on periodically deformed polymers
1984
Small angle neutron scattering from periodically deformed samples is a useful extension of the methods presently available for the study of molecular dynamics of polymers. In this paper we describe apparatus that has been used to produce large cyclic deformations at frequencies upto 10 Hz and the principles by which data is collected to give spectra corresponding to different states of strain of the sample. Some data on model polydimethylsiloxane networks is given as an illustration of the value of this technique.
Modelling of Reflectance Spectra of Skin Phototypes III
2011
In dermatology, study of human skin colour is related to skin phototype (SPT) in which the Fitzpatrick's scale is the most used skin photo type classification. Assessment of skin response to UV for various reasons plays an important role in dermatology. This is however not easy to be performed because of two reasons. Firstly, skin areas may have different skin tone resulting in different reflectance spectra and secondly, different modalities may produce different reflectance spectra. We hypothesize that the underlying pattern of reflectance spectra must be similar regardless of the modalities use and the skin areas where it is obtained, for a particular person. An observational clinical stu…
Combined multi-wavelength laser speckle contrast imaging and diffuse reflectance imaging for skin perfusion assessment
2019
Abstract Laser Speckle Contrast Imaging (LSCI) is a powerful low-cost method for visualization of flow, microcirculation and blood perfusion. Due to the fact that diseased and healthy tissues has different blood perfusion, LSCI can be a perspective tool for cancer diagnostics and discrimination between different types of tissues. Previously, multispectral diffuse reflectance imaging method for melanoma diagnostics has been introduced. In this work, multi-wavelength (532-, 655- and 850- nm) LSCI technique combined with hyperspectral camera and diffuse reflectance imaging method will be used for assessment of tissues with different skin perfusion properties. An in vivo experiment with occlusi…
Collective optical resonances in networks of metallic carbon nanotubes
2013
Abstract We demonstrate that thin films of randomly oriented metallic single-walled carbon nanotubes possess optical resonances with significant dispersion. The resonances are observed in the Kretschmann configuration as minima in reflection spectra close to 400 nm and 700 nm wavelengths. The dispersions are visible only when the material is excited with s -polarized light, and most prominent in layers with thickness near 100 nm. We conclude that magnetic plasmon polaritons arising from intertube interactions are a likely explanation. Closeness of the M 11 and M 22 transition energies to the observed resonances points to a possible coupling with excitons.
Types and Multiplicity of Solutions to Sturm–Liouville Boundary Value Problem
2015
We consider the second-order nonlinear boundary value problems (BVPs) with Sturm–Liouville boundary conditions. We define types of solutions and show that if there exist solutions of different types then there exist intermediate solutions also.
On the Accuracy and Efficiency of Transient Spectral Element Models for Seismic Wave Problems
2016
This study concentrates on transient multiphysical wave problems for simulating seismic waves. The presented models cover the coupling between elastic wave equations in solid structures and acoustic wave equations in fluids. We focus especially on the accuracy and efficiency of the numerical solution based on higher-order discretizations. The spatial discretization is performed by the spectral element method. For time discretization we compare three different schemes. The efficiency of the higher-order time discretization schemes depends on several factors which we discuss by presenting numerical experiments with the fourth-order Runge-Kutta and the fourth-order Adams-Bashforth time-steppin…