Theoretical thermo-optical patterns relevant to glass crystallisation

2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Miroslav Kocifaj ◽  
Vladimír Kovár ◽  
Ján Majling
Keyword(s):  
Input Data ◽  
Optical Transmission ◽  
Spherical Shape ◽  
Lithium Disilicate ◽  
Number Density ◽  
Thermal Methods ◽  
Transmission Measurements ◽  
Glass Slab ◽  
Glass Crystallisation ◽  
Individual Input

AbstractMie computations are performed to evaluate light scattering on the virtual microstructures relevant to lithium disilicate glass internal crystallisation. The computations are expressed in the form of optical transmission (OT) patterns evolved on a scale of growing lithium disilicate crystals. Input data include the crystals number density, their size, the wavelength of the incident electromagnetic radiation, the indices of refraction of the lithium disilicate glassy and crystalline phases and the thickness of the virtual glass slab. In the computations, the spherical shape of crystals and their random distribution are assumed. The results reveal the quantitative effects of individual input data constants on the overall course of the computed OT patterns. They also relate the computed OT data magnitudes to the corresponding glass crystallinity (α). In addition, they point to singular combinations of the input data constants defining the conditions under which the OT data could potentially stand for the kinetically important α data. Finally, the results aid better recognition of some fundamental as well as practical properties of the optical thermal methods based on the optical transmission measurements.

scholarly journals Terahertz characterization of two-dimensional low-conductive layers enabled by metal gratings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Prashanth Gopalan ◽  
Yunshan Wang ◽  
Berardi Sensale-Rodriguez
Keyword(s):  
Optical Transmission ◽  
Terahertz Spectroscopy ◽  
Design Guidelines ◽  
Two Dimensional ◽  
Highly Sensitive ◽  
Transmission Measurements ◽  
Metal Gratings ◽  
Low Sensitivity ◽  
Non Destructive

AbstractWhile terahertz spectroscopy can provide valuable information regarding the charge transport properties in semiconductors, its application for the characterization of low-conductive two-dimensional layers, i.e., σs <  < 1 mS, remains elusive. This is primarily due to the low sensitivity of direct transmission measurements to such small sheet conductivity levels. In this work, we discuss harnessing the extraordinary optical transmission through gratings consisting of metallic stripes to characterize such low-conductive two-dimensional layers. We analyze the geometric tradeoffs in these structures and provide physical insights, ultimately leading to general design guidelines for experiments enabling non-contact, non-destructive, highly sensitive characterization of such layers.

scholarly journals Sensitivities of Lagrangian modelling of mid-latitude cirrus clouds to trajectory data quality

2015 ◽  
Vol 15 (13) ◽  
pp. 7429-7447 ◽  
Author(s):  
E. Kienast-Sjögren ◽  
A. K. Miltenberger ◽  
B. P. Luo ◽  
T. Peter
Keyword(s):  
Cooling Rate ◽  
Temporal Resolution ◽  
Vertical Velocity ◽  
Input Data ◽  
Temperature Fluctuations ◽  
Box Model ◽  
Specific Humidity ◽  
Number Density ◽  
Ice Nuclei ◽  
Nuclei Number

Abstract. Simulations of cirrus are subject to uncertainties in model physics and meteorological input data. Here we model cirrus clouds along air mass trajectories, whose extinction has been measured with an elastic backscatter lidar at Jungfraujoch research station in the Swiss Alps, with a microphysical stacked box model. The sensitivities of these simulations to input data uncertainties (trajectory resolution, unresolved vertical velocities, ice nuclei number density and upstream specific humidity) are investigated. Variations in the temporal resolution of the wind field data (COSMO-Model at 2.2 km resolution) between 20 s and 1 h have only a marginal impact on the trajectory path, while the representation of the vertical velocity variability and therefore the cooling rate distribution are significantly affected. A temporal resolution better than 5 min must be chosen in order to resolve cooling rates required to explain the measured extinction. A further increase in the temporal resolution improves the simulation results slightly. The close match between the modelled and observed extinction profile for high-resolution trajectories suggests that the cooling rate spectra calculated by the COSMO-2 model suffice on the selected day. The modelled cooling rate spectra are, however, characterized by significantly lower vertical velocity amplitudes than those found previously in some aircraft campaigns (SUCCESS, MACPEX). A climatological analysis of the vertical velocity amplitude in the Alpine region based on COSMO-2 analyses and balloon sounding data suggests large day-to-day variability in small-scale temperature fluctuations. This demonstrates the necessity to apply numerical weather prediction models with high spatial and temporal resolutions in cirrus modelling, whereas using climatological means for the amplitude of the unresolved air motions does generally not suffice. The box model simulations further suggest that uncertainties in the upstream specific humidity (± 10 % of the model prediction) and in the ice nuclei number density (0–100 L−1) are more important for the modelled cirrus cloud than the unresolved temperature fluctuations if temporally highly resolved trajectories are used. For the presented case the simulations are incompatible with ice nuclei number densities larger than 20 L−1 and insensitive to variations below this value.

A New Magnetooptical Effect Discovered on Magnetic Multilayers: The Magnetorefractive Effect

1995 ◽  
Vol 384 ◽  
Author(s):  
J. C. Jacquet ◽  
T. Valet
Keyword(s):  
Magnetic Field ◽  
Optical Transmission ◽  
Theoretical Calculations ◽  
Wavelength Region ◽  
Magnetic Multilayers ◽  
Light Wavelength ◽  
Metallic Multilayers ◽  
Magnetooptical Effect ◽  
Transmission Measurements ◽  
Magnetorefractive Effect

ABSTRACTWe show theoretically that the change in the magnetization structure of magnetic metallic multilayers under the application of a magnetic field shall be generally associated with a significant change of the refractive index. This constitutes a new magnetooptical effect: the magnetorefractive effect.Optical transmission measurements under an applied magnetic field through [Ni80Fe20/Cu/Co/Cu] multilayers, in the light wavelength region between 2 μm and 20 μm, clearly demonstrate the existence of the predicted effect and are found in reasonnable agreement with the theoretical calculations.

Transition Metal-Doped ZnO: A Comparison of Optical, Magnetic, and Structural Behavior of Bulk and Thin Films

2006 ◽  
Vol 957 ◽  
Author(s):  
William E. Fenwick ◽  
Matthew H. Kane ◽  
Zaili Fang ◽  
Tahir Zaidi ◽  
Nola Li ◽  
...  
Keyword(s):  
Thin Films ◽  
Transition Metal ◽  
Optical Transmission ◽  
Magnetic Hysteresis ◽  
Structural Quality ◽  
Bulk Crystals ◽  
Transmission Measurements ◽  
Doped Zno ◽  
Metal Doped ◽  
Metal Incorporation

ABSTRACTTransition metal-doped ZnO bulk crystals and thin films have been investigated to determine the effects of transition metal incorporation on optical, magnetic, and structural properties of ZnO. A modified melt growth technique was used to grow bulk Zn1-xMnxO, Zn1-xCoxO, and Zn1-xFexO. Optical transmission measurements show an apparent shift in absorption edge with increasing transition metal incorporation. Raman spectroscopy also shows increasing lattice disorder with increasing transition metal concentration. ZnO thin films doped with Ni, Co, and Gd were grown by metalorganic chemical vapor deposition (MOCVD). While the Co-doped thin films showed antiferromagnetic behavior, magnetic hysteresis was observed in the Ni-doped and Gd-doped thin films. Structural quality was verified with X-ray diffraction (XRD), and optical properties were investigated using room temperature photoluminescence (PL) and optical transmission measurements. Properties of ZnO:TM bulk crystals and thin films are compared and used to discuss possible origins of ferromagnetism in these materials.

Spin polarized conduction and valence band states in GdN

MRS Advances ◽  
2017 ◽  
Vol 2 (3) ◽  
pp. 153-158 ◽  
Author(s):  
Muhammad Azeem
Keyword(s):  
Valence Band ◽  
Optical Transmission ◽  
Energy Gap ◽  
Ferromagnetic State ◽  
Spin Splitting ◽  
Transmission Spectra ◽  
Temperature Dependent ◽  
Spin Polarized ◽  
Transmission Measurements ◽  
Optical Transmission Spectra

AbstractOptical transmission spectra are collected in the ferromagnetic state of GdN at various temperatures. The temperature dependent extinction coefficient extracted from the transmission measurements show that the conduction and valence band states are spin polarized. The results confirm the LSDA+U estimates of the energy gap associated with the majority/minority-spins and also the magnitude of the spin splitting.

Optical Transmission Measurements on MOCVD Grown GaMnN Films on Sapphire

2006 ◽  
Vol 955 ◽  
Author(s):  
Fevzi Erdem Arkun ◽  
Nadia A El-Masry ◽  
John Muth ◽  
Xiyao Zhang ◽  
Amr Mahrouse ◽  
...  
Keyword(s):  
Absorption Band ◽  
Energy Band ◽  
Optical Transmission ◽  
Chemical Vapor ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Broad Absorption Band ◽  
Co Doping ◽  
Transmission Measurements ◽  
Mn Concentration

ABSTRACTWe demonstrate optical transmission measurements performed on 1.2 μm thick GaMnN films grown by metalorganic chemical vapor deposition on (0001) sapphire substrates. According to the data acquired from these measurements, Mn forms a deep acceptor band at 1.4 eV above the valance band of GaMnN. Full width at half maximum of this absorption band increases from 107 meV to 198meV as the Mn concentration increases from 0.3% to 1.6 %; which indicates that this band becomes wider as the concentration of Mn increases in the lattice. A broad absorption band starting at 1.9eV and extending to the band edge of GaMnN was also determined. This was attributed to the transition from the Mn energy band to the conduction band edge of GaMnN. Absorption at both of these bands scales with the Mn concentration and thickness of the films. The effect of co-doping of GaMnN films with magnesium on the transmission spectra was also investigated. The absorption band initially observed at 1.4 eV was shifted to 1.6 eV as a result of introduction of Magnesium into the lattice of GaMnN. From these results we conclude that Mn is incorporated in the lattice and forms an energy band in the bandgap of GaMnN. The width of this energy band is also a function of the Mn concentration in GaMnN.

Photostimulated Changes of Electrical Characteristics of Ag/CdTe Thin Film Structures

2005 ◽  
Vol 865 ◽  
Author(s):  
T.D. Dzhafarov ◽  
M. Caliskan
Keyword(s):  
Optical Transmission ◽  
Energy Levels ◽  
Effective Diffusion ◽  
Electrical Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Dependence Of Conductivity ◽  
Transmission Measurements ◽  
Cdte Films ◽  
Xrd Patterns

AbstractElectrical, optical and structural properties of Ag/CdTe structures exposed to thermal (in dark) and photoannealing (under illumination) have been studied. The effective diffusion coefficie nt of Ag in CdTe films have been estimated from resistance versus duration of annealing curves. In the range of 280-420°C the effective coefficient of thermal diffusion (Dt) and photodiffusion (Dph) are described as Dt= 1.9x105exp (-1.60/kT) and Dph =8.7x103exp(-1.36/kT). The acceleration of Ag diffusion under illumination was tentatively attributed to photoionization of Ag increasing the interstitial flux of silver. Ag/CdTe structures exposed to annealing were characterized by X-ray diffraction (XRD), I-V, C-V, conductivity-temperature and optical transmission measurements. In XRD patterns of annealed Ag/CdTe structures, besides the intensive (111) peak of cubic CdTe, the weak peaks of Ag2Te phase are also present. The temperature dependence of conductivity of annealed Ag/CdTe structures showed the energy levels 0.13 eV.

Limits of optical transmission measurements with application to particle sizing techniques

1999 ◽  
Vol 38 (27) ◽  
pp. 5887 ◽  
Author(s):  
Nancy L. Swanson ◽  
Barton D. Billard ◽  
Theresa L. Gennaro
Keyword(s):  
Optical Transmission ◽  
Particle Sizing ◽  
Transmission Measurements
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