Thermal Shift and Broadening of Spectral Lines in Neodymium Doped Garnets

1999 ◽  
Vol 560 ◽  
Author(s):  
Xuesheng Chen ◽  
Baldassare Di Bartolo
Keyword(s):  
Line Width ◽  
Blue Shift ◽  
Red Shift ◽  
Spectral Lines ◽  
Temperature Range ◽  
Different Temperatures ◽  
Line Widths ◽  
Increasing Temperature ◽  
Thermal Shift

ABSTRACTThermal shift and broadening of sharp luminescence lines in three Nd-doped laser garnet crystals, GGG, GSGG, and CYMGG, are investigated in a temperature range of 78 to 600K. These lines are due to the 4F3/2 → 4I9/2 (∼0.94μ) and 4F3/2 → 4I11/2 (∼lμ) transitions. Line widths and positions at different temperatures are reported for the lines of RI→Yl, RI→Y2, R2→Y3, RI→Z5 in GGG:Nd, RI→Y1, RI→Y2, R2→Y1, R2→Y3, RI→Y6, R2→Y6, RI→Z5 in GSGG:Nd,Cr, and R2→Y1, RI→Z5 in CYMGG:Nd,Cr. We observed that all the lines shift to longer wavelengths (red shift) with increasing temperature except for the R1,2 →Z5 lines that shift to shorter wavelength (blue shift) in all the three garnet crystals. For the widths, all the lines become broader with increasing temperature. It was also observed that the line width in the germanium garnet CYMGG is much broader than in GGG and GSGG.

scholarly journals Temperature / pressure-dependent luminescence spectra of square-planar complexes

2014 ◽  
Vol 70 (a1) ◽  
pp. C1714-C1714
Author(s):  
Stéphanie Poirier ◽  
Christian Reber ◽  
Pierre Libioulle
Keyword(s):  
Structural Changes ◽  
Theoretical Calculations ◽  
Blue Shift ◽  
Red Shift ◽  
Crystalline Lattice ◽  
Luminescence Spectra ◽  
Electron Configuration ◽  
Square Planar ◽  
Square Planar Complexes ◽  
Increasing Temperature

Luminescence properties of square-planar complexes of platinum(II) and palladium(II) with a d8 electron configuration were investigated. Blue shift of the maxima of the luminescence spectra occur for pressure-dependent spectra of several complexes of both metals. This is due to a structural compression of the crystalline lattice, which causes a destabilization of the LUMO orbital for theses complexes. Other structural changes can also occur, providing a more important slope of the blue shift. Also, intermolecular interactions cause a red shift in pressure-dependent spectra. In temperature-dependent spectra, opposite trends occur for several analog complexes. Palladium(II) complexes show a red shift of luminescence maxima with increasing temperature. Platinum(II) compounds exhibit a blue shift. This difference is explained with theoretical calculations of luminescence spectra. In these trends, the dominant effect is due to an increase of vibronic contributions with temperature. We also present a complex of platinum(II) in which the structural effect is dominant in the spectra with increasing temperature, leading to a red shift. This rare effect allows the study of structural changes with temperature for square-planar platinum(II) complex.

Crystal structure of adamite at high temperature

2016 ◽  
Vol 80 (5) ◽  
pp. 901-914 ◽  
Author(s):  
M. Zema ◽  
S. C. Tarantino ◽  
M. Boiocchi ◽  
A. M. Callegari
Keyword(s):  
Crystal Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Expansion ◽  
Cell Parameters ◽  
Temperature Range ◽  
Linear Evolution ◽  
Thermal Expansion Coefficients ◽  
Different Temperatures ◽  
Increasing Temperature

AbstractStructural modifications with temperature of adamite, Zn2(AsO4)(OH), were determined by single-crystal X-ray diffraction up to dehydration and collapse of the crystal structure. In the temperature range 25–400°C, adamite shows positive and linear expansion. Axial thermal expansion coefficients, determined over this temperature range, are αa = 1.06(2) × 10–5 K–1, αb = 1.99(2) × 10–5 K–1, αc = 3.7(1) × 10–6 K–1 and αV = 3.43(3) × 10–5 K–1. Axial expansion is then strongly anisotropic with αa:αb:αc = 2.86: 5.38 : 1. Structure refinements of X-ray diffraction data collected at different temperatures allowed us to characterize the mechanisms by which the adamite structure accommodates variations in temperature. Expansion is limited mainly by edge sharing Zn(2) dimers along a and by edge sharing Zn(1) octahedra chains along c; on the other hand, connections of polyhedra along b, the direction of maximum expansion, is governed by corner sharing. Increasing temperature induces mainly an axial expansion of Zn(1) octahedron, which becomes more elongated, and no significant variations of the Zn(2) trigonal bipyramids and As tetrahedra. Starting from 400°C, deviation from a linear evolution of unit-cell parameters is observed, associated with some deterioration of the crystal, a sign of incipient dehydration. The process leads to the formation of Zn4(AsO4)2O.

Microphotometric Errors for Photographically Recorded Spectral Lines of Nonuniform Half-Width

1978 ◽  
Vol 32 (5) ◽  
pp. 433-444 ◽  
Author(s):  
L. C. McGonagle ◽  
J. A. Holcombe
Keyword(s):  
Line Width ◽  
Half Width ◽  
Slit Width ◽  
Spectral Lines ◽  
Average Error ◽  
Spatially Resolved ◽  
Source Line ◽  
Line Widths ◽  
Spectrometer Slit ◽  
The Impact

Various microphotometric (or densitometric) techniques for generating quantitative intensity information from photographically recorded spectral lines of time or spatially resolved sources are discussed. The impact of various parameters on the accuracy of quantitative densitometry is presented. These parameters include line widths of the calibration spectrum, source line broadening, microphotometer scan slit width and the optical density of the photographic image. Nonrandom errors associated with the use of various microphotometer slit widths for spectral lines of nonuniform half-width are presented. Spectral lines which are uniform and exhibit slit width or diffraction limited resolution can be scanned with any size microphotometer slit width as long as the calibration curve is prepared using the same scan slit width. The use of microphotometer slit widths narrower than the line width produce H and D curves with maximal γ and increased accuracy in the final intensity value. A density-to-intensity conversion accuracy with a 6% average error was determined for SA-1 plates. For sources whose line widths are larger than the spectrometer bandpass, minimal errors are generated by using a narrow line source for calibration and scanning this spectrum with a slit width less than the line width. Scanning of the broadened line of interest is accomplished using a scan slit width equal to approximately twice the spectrometer slit width. Under these conditions an average error of approximately 11% was determined experimentally for SA-1 plates.

scholarly journals Defect Luminescence in Heavily Mg Doped GaN

1999 ◽  
Vol 4 (S1) ◽  
pp. 968-973 ◽  
Author(s):  
M. A. Reshchikov ◽  
G.-C. Yi ◽  
B. W. Wessels
Keyword(s):  
Thermal Activation ◽  
Blue Shift ◽  
Excitation Intensity ◽  
Thermal Release ◽  
Deep Donor ◽  
Different Temperatures ◽  
Donor Acceptor ◽  
Increasing Temperature ◽  
Defect Luminescence ◽  
Mg Doped

Behavior of the photoluminescence band at about 2.8 eV in heavily Mg doped GaN has been studied at different temperatures and excitation intensities. The 2.8 eV band is attributed to donor-acceptor transitions involving a Mg acceptor. The large blue shift of the band with increasing excitation intensity is explained by variation in the contribution of close and distant pairs to the luminescence. The red shift of the band with increasing temperature under high excitation intensity conditions results from thermal release of carriers from close pairs. The thermal activation energy of the deep donor, about 0.4 eV, is determined from the quenching of the 2.8 eV luminescence band at high temperatures.

Defect Luminescence in Heavily Mg Doped GaN

1998 ◽  
Vol 537 ◽  
Author(s):  
M. A. Reshchikov ◽  
G.-C. Yi ◽  
B. W. Wessels
Keyword(s):  
Thermal Activation ◽  
Blue Shift ◽  
Excitation Intensity ◽  
Thermal Release ◽  
Deep Donor ◽  
Different Temperatures ◽  
Donor Acceptor ◽  
Increasing Temperature ◽  
Defect Luminescence ◽  
Mg Doped

AbstractBehavior of the photoluminescence band at about 2.8 eV in heavily Mg doped GaN has been studied at different temperatures and excitation intensities. The 2.8 eV band is attributed to donor-acceptor transitions involving a Mg acceptor. The large blue shift of the band with increasing excitation intensity is explained by variation in the contribution of close and distant pairs to the luminescence. The red shift of the band with increasing temperature under high excitation intensity conditions results from thermal release of carriers from close pairs. The thermal activation energy of the deep donor, about 0.4 eV, is determined from the quenching of the 2.8 eV luminescence band at high temperatures.

Thermal behaviour of libethenite from room temperature up to dehydration

2010 ◽  
Vol 74 (3) ◽  
pp. 553-565 ◽  
Author(s):  
M. Zema ◽  
S. C. Tarantino ◽  
A. M. Callegari
Keyword(s):  
X Ray Diffraction ◽  
Oh Groups ◽  
X Ray ◽  
Structural Modifications ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Different Temperatures ◽  
Expansion Coefficients ◽  
Increasing Temperature ◽  
Diffraction Effects

AbstractThe structural modifications with temperature of libethenite, Cu2(PO4)(OH), were determined by single-crystal X-ray diffraction up to dehydration and consequent decomposition of the crystal under investigation. In the temperature range 25–475°C, libethenite shows positive and linear expansion. The axial thermal expansion coefficients, determined over this temperature range, are: αa = 6.6(1)·10–6 K–1, αb = 1.21(2)·10–5 K–1, αc = 9.0(2)·10–6 K–1, αv = 2.78(3)·10–5 K–1. Axial expansion is then anisotropic with αa:αb:αc = 1:1.83:1.33.Structure refinements of X-ray diffraction data collected at different temperatures allowed us to characterize the mechanisms by which the libethenite structure accommodates variations in temperature. Increasing temperature induces expansion of both Cu polyhedra and no significant variation of the PO4 tetrahedron, which acts as a rigid unit. Cu(1) octahedra expand mostly as a consequence of the increase of the axial bonds, and become more distorted. Starting from T = 500°C, precursor signs of incoming dehydration are visible: two adjacent OH groups approach each other and cause dramatic changes in the whole structure. Concomitantly, the libethenite crystal begins to deteriorate and, at T = 600°C, broad and weak diffraction effects of polycrystalline material are observed.

scholarly journals A Comparative Electrochemical and Morphological Investigation on the Behavior of NiCr and CoCr Dental Alloys at Various Temperatures

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 256
Author(s):  
Florentina Golgovici ◽  
Mariana Prodana ◽  
Florentina Gina Ionascu ◽  
Ioana Demetrescu
Keyword(s):  
Low Temperatures ◽  
Artificial Saliva ◽  
Electrochemical Stability ◽  
Morphological Investigation ◽  
Dental Alloys ◽  
Ion Release ◽  
Icp Ms ◽  
Different Temperatures ◽  
Good Concordance ◽  
Increasing Temperature

The purpose of our study is to compare the behavior of two reprocessed dental alloys (NiCr and CoCr) at different temperatures considering the idea that food and drinks in the oral cavity create various compositions at different pH levels; the novelty is the investigation of temperature effect on corrosion parameters and ion release of dental alloys. Electrochemical stability was studied together with morphology, elemental composition and ions release determination. The results obtained are in good concordance: electrochemistry studies reveal that the corrosion rate is increasing by increasing the temperature. From SEM coupled with EDS, the oxide film formed on the surface of the alloys is stable at low temperatures and a trend to break after 310K. ICP-MS results evidence that in accordance with increasing temperature, the quantities of ions released from the alloys immersed in artificial saliva also increase, though they still remain small, less than 20 ppm.

scholarly journals Cell mechanical properties of human breast carcinoma cells depend on temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christian Aermes ◽  
Alexander Hayn ◽  
Tony Fischer ◽  
Claudia Tanja Mierke
Keyword(s):  
Mechanical Properties ◽  
Power Law ◽  
Cell Mechanics ◽  
Cell Types ◽  
Creep Response ◽  
Temperature Range ◽  
Myosin Filaments ◽  
Cell Mechanical Properties ◽  
Increasing Temperature ◽  
Mcf 7

AbstractThe knowledge of cell mechanics is required to understand cellular processes and functions, such as the movement of cells, and the development of tissue engineering in cancer therapy. Cell mechanical properties depend on a variety of factors, such as cellular environments, and may also rely on external factors, such as the ambient temperature. The impact of temperature on cell mechanics is not clearly understood. To explore the effect of temperature on cell mechanics, we employed magnetic tweezers to apply a force of 1 nN to 4.5 µm superparamagnetic beads. The beads were coated with fibronectin and coupled to human epithelial breast cancer cells, in particular MCF-7 and MDA-MB-231 cells. Cells were measured in a temperature range between 25 and 45 °C. The creep response of both cell types followed a weak power law. At all temperatures, the MDA-MB-231 cells were pronouncedly softer compared to the MCF-7 cells, whereas their fluidity was increased. However, with increasing temperature, the cells became significantly softer and more fluid. Since mechanical properties are manifested in the cell’s cytoskeletal structure and the paramagnetic beads are coupled through cell surface receptors linked to cytoskeletal structures, such as actin and myosin filaments as well as microtubules, the cells were probed with pharmacological drugs impacting the actin filament polymerization, such as Latrunculin A, the myosin filaments, such as Blebbistatin, and the microtubules, such as Demecolcine, during the magnetic tweezer measurements in the specific temperature range. Irrespective of pharmacological interventions, the creep response of cells followed a weak power law at all temperatures. Inhibition of the actin polymerization resulted in increased softness in both cell types and decreased fluidity exclusively in MDA-MB-231 cells. Blebbistatin had an effect on the compliance of MDA-MB-231 cells at lower temperatures, which was minor on the compliance MCF-7 cells. Microtubule inhibition affected the fluidity of MCF-7 cells but did not have a significant effect on the compliance of MCF-7 and MDA-MB-231 cells. In summary, with increasing temperature, the cells became significant softer with specific differences between the investigated drugs and cell lines.

scholarly journals Simulation of FDSOI-ISFET with Tunable Sensitivity by Temperature and Dual-Gate Structure

Electronics ◽  
2021 ◽  
Vol 10 (13) ◽  
pp. 1585
Author(s):  
Hanbin Wang ◽  
Jinshun Bi ◽  
Mengxin Liu ◽  
Tingting Han
Keyword(s):  
Gate Voltage ◽  
Computer Aided Design ◽  
Silicon On Insulator ◽  
Fully Depleted ◽  
Gate Structure ◽  
Different Temperatures ◽  
Dual Gate ◽  
Sensitivity Changes ◽  
Increasing Temperature ◽  
Aided Design

This work investigates the different sensitivities of an ion-sensitive field-effect transistor (ISFET) based on fully depleted silicon-on-insulator (FDSOI). Using computer-aided design (TCAD) tools, the sensitivity of a single-gate FDSOI based ISFET (FDSOI-ISFET) at different temperatures and the effects of the planar dual-gate structure on the sensitivity are determined. It is found that the sensitivity increases linearly with increasing temperature, reaching 890 mV/pH at 75 °C. By using a dual-gate structure and adjusting the control gate voltage, the sensitivity can be reduced from 750 mV/pH at 0 V control gate voltage to 540 mV/pH at 1 V control gate voltage. The above sensitivity changes are produced because the Nernst limit changes with temperature or the electric field generated by different control gate voltages causes changes in the carrier movement. It is proved that a single FDSOI-ISFET can have adjustable sensitivity by adjusting the operating temperature or the control gate voltage of the dual-gate device.

scholarly journals Correlation and prediction of solubility of hydrogen in alkenes and its dissolution properties

2021 ◽  
Author(s):  
Mohammad Jamali ◽  
Amir Abbas Izadpanah ◽  
Masoud Mofarahi
Keyword(s):  
Equation Of State ◽  
Binary Interaction ◽  
Absolute Deviation ◽  
Dissolution Properties ◽  
Different Temperatures ◽  
Binary Interaction Parameters ◽  
Delta G ◽  
Hoff Equation ◽  
Increasing Temperature ◽  
Total Average

AbstractIn this work, solubility of hydrogen in some alkenes was investigated at different temperatures and pressures. Solubility values were calculated using the Peng–Robinson equation of state. Binary interaction parameters were calculated using fitting the equation of state on experimental data, Group contribution method and Moysan correlations and total average absolute deviation for these methods was 3.90, 17.60 and 13.62, respectively. Because hydrogen solubility in Alkenes is low, Henry’s law for these solutions were investigated, too. Results of calculation showed with increasing temperature, Henry’s constant was decreased. The temperature dependency of Henry’s constants of hydrogen in ethylene and propylene was higher than to other alkenes. In addition, using Van’t Hoff equation, the thermodynamic parameters for dissolution of hydrogen in various alkenes were calculated. Results indicated that the dissolution of hydrogen was spontaneous and endothermic. The total average of dissolution enthalpy ($${\Delta H}^{^\circ }$$ Δ H ∘ ) and Gibbs free energy ($${\Delta G}^{^\circ }$$ Δ G ∘ ) for these systems was 3.867 kJ/mol and 6.361 kJ/mol, respectively. But dissolution of hydrogen in almost of alkenes was not an entropy-driven process.

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