A Full Analysis Including Both the Static and Dynamic Factors for the Thermal Shift of 7D0 ⟶ 5F0 Fluorescence Line in SrB4O7:Sm2+Crystal

2019 ◽  
Vol 74 (3) ◽  
pp. 265-267
Author(s):  
Xiao-Xuan Wu ◽  
Min Cheng
Keyword(s):  
Room Temperature ◽  
Coupling Parameter ◽  
Blue Shift ◽  
Dynamic Factor ◽  
Electron Phonon Interaction ◽  
Dynamic Factors ◽  
Two Factors ◽  
Static Factor ◽  
Fluorescence Line ◽  
Thermal Shift

AbstractA complete formula consisting of the static factor stemming from lattice thermal expansion and the dynamic factor owing to electron-phonon interaction is employed to investigate the thermal shift at near and higher than room temperature for the 7D0⟶5F0 fluorescence line in strontium tetraborate (SrB4O7):Sm2+ crystal. The static factor is gained in terms of the pressure dependence of the fluorescence line. With the aid of an approximate processing, the static parameter A (characterising the static factor) and the electron-phonon coupling parameter α’ (characterising the dynamic factor) are estimated even if there is no observed thermal shift curve from low temperature (<30 K) to near and higher than room temperature. The static factor and dynamic one in SrB4O7:Sm2+ crystal give rise to the thermal blue shift and red shift, respectively, and the total or observed thermal shift is due to the emulation between the two factors. The static factor in shift direction is contrary to and in magnitude is slightly greater than the dynamic one for the 7D0⟶5F0 line in SrB4O7:Sm2+ crystal. Thus, the observed very small thermal blue shift (which is not explained up to now) for the studied line in SrB4O7:Sm2+ crystal is rationally explained.

Thermal Shifts and Electron-Phonon Coupling Parameters for the Three Luminescence Lines of 5DJ→7FJ in SrFCl:Sm2+ Crystal

2018 ◽  
Vol 73 (7) ◽  
pp. 657-659 ◽  
Author(s):  
Yang Mei ◽  
Hong-Gang Liu ◽  
Wen-Chen Zheng
Keyword(s):  
Coupling Parameter ◽  
Blue Shift ◽  
Simple Expression ◽  
Spectral Lines ◽  
Phonon Coupling ◽  
Lattice Thermal Expansion ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Coupling Parameters ◽  
Vibrational Contribution

AbstractThe thermal blue shifts of three spectral lines E1(5D0→7F0), E2(5D0→7F1), and E3(5D1→7F0) in SrFCl:Sm2+ crystal are investigated by a complete expression consisting of both the static contribution due to lattice thermal expansion and the vibrational contribution owing to electron-phonon interaction. The obtained true electron-phonon coupling parameters α′ in both sign and magnitude are considerably different from the apparent electron-phonon coupling parameters α acquired in the previous paper by considering only the vibrational contribution. It is suggested that differing from the simple expression including only the vibrational contribution (many authors thought that it cannot be used to explain the thermal blue shifts), the complete expression containing both the vibrational and static contributions is effective in the studies of thermal shift (whether red shift or blue shift) and true electron-phonon coupling parameter for a spectral line in crystals.

Synthesis and Luminescence Properties of Tris (8-Hydroxyquinoline) Iron Spindle-Like Structures at Room Temperature

2011 ◽  
Vol 391-392 ◽  
pp. 225-229 ◽  
Author(s):  
Qing Hong Kong ◽  
Hong Liu ◽  
Yun Long Zhang ◽  
Yong Sheng Yan
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Blue Shift ◽  
Solvent System ◽  
Iron Complex ◽  
Molecular Formula ◽  
Gravimetric Analysis ◽  
Element Analysis ◽  
Transmission Electron ◽  
Fourier Transformation Infrared Spectroscopy

Spindle-like bis (8-hydroxyquinoline) iron (FeQ3) complex has been synthesized with a facile method in a mixed solvent system at room temperature for 12 h. The molecular formula of the products is speculated by the C, H and N element analysis and thermal gravimetric analysis, and Fourier-transformation infrared spectroscopy was also utilized to measure its structure, which further confirm the molecular formula of the products. The observation of field emission scanning electron microscopy and transmission electron microscopy shows that the morphology of tris (8-hydroxyquinoline) iron complex is spindle-like structure. The photoluminescence of the products were also investigated. The results indicate that the photoluminescence emission of FeQ3spindles shows obvious blue shift contrasted with that of 8-hydroxyquinoline.

PATH-INTEGRAL APPROACH FOR ELECTRON–PHONON INTERACTION EFFECTS IN HARMONIC QUANTUM DOTS

1996 ◽  
Vol 10 (22) ◽  
pp. 2781-2796 ◽  
Author(s):  
SOMA MUKHOPADHYAY ◽  
ASHOK CHATTERJEE
Keyword(s):  
Quantum Dots ◽  
Path Integral ◽  
State Energy ◽  
Coupling Parameter ◽  
Three Dimensions ◽  
Integral Approach ◽  
Phonon Coupling ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Parabolic Confinement

We use the Feynman–Haken path-integral formalism to obtain the polaronic correction to the ground state energy of an electron in a polar semiconductor quantum dot with parabolic confinement in both two and three dimensions. We perform calculations for the entire range of the electron–phonon coupling parameter and for arbitrary confinement length. We apply our results to several semiconductor quantum dots and show that the polaronic effect in some of these dots can be considerably large if the dot sizes are made smaller than a few nanometers.

Polarization effects in AlxGa1−xN / GaN superlattices

2000 ◽  
Vol 639 ◽  
Author(s):  
Erik L. Waldron ◽  
E. Fred Schubert ◽  
John W. Graff ◽  
Andrei Osinsky ◽  
Michael J. Murphy ◽  
...  
Keyword(s):  
Room Temperature ◽  
Stark Effect ◽  
Blue Shift ◽  
Transition Band ◽  
Polarization Effects ◽  
Quantum Confined Stark Effect ◽  
Free Carriers ◽  
Bulk Gan ◽  
Band Transition ◽  
Photoluminescence Studies

ABSTRACTRoom temperature and low temperature photoluminescence studies of AlxGa1−xN/GaN superlattices reveal a red shift of the dominant transition band relative to the bulk GaN bandgap. The shift is attributed to the quantum-confined Stark effect resulting from polarization fields in the superlattices. A theoretical model for the band-to-band transition energies based on perturbation theory and a variational approach is developed. Comparison of the experimental data with this model yields a polarization field of 4.6 × 105 V/cm for room temperature Al0.1Ga0.9N/GaN and 4.5 × 105 V/cm for room temperature Al0.2Ga0.8N/GaN. At low temperatures the model yields 5.3 × 105 V/cm for Al0.1Ga0.9N/GaN and 6.3 × 105 V/cm for Al0.2Ga0.8N/GaN. The emission bands exhibit a blue shift at high excitation densities indicating screening of internal polarization fields by photo-generated free carriers.

scholarly journals The Effect of Processing and Cooling Methods on Coleus tuberosus in vitro Starch Digestibility

2021 ◽  
Vol 41 (3) ◽  
pp. 238
Author(s):  
Jhauharotul Muchlisyiyah ◽  
Tri Dewanti Widyaningsih ◽  
Retno Wulansari ◽  
Hera Sisca Prasmita
Keyword(s):  
Resistant Starch ◽  
Room Temperature ◽  
Potato Starch ◽  
Block Design ◽  
In Vitro Digestibility ◽  
Randomized Block Design ◽  
Two Factors ◽  
Cooling Methods ◽  
Total Starch

Coleus tuberosus, also known as black potato, is one of the Indonesian local tubers consumed as a carbohydrate substituent. Therefore, this study aimed to examine the effect of processing and cooling methods on the in vitro digestibility of black potato starch. Furthermore, two factors Randomized Block Design with a 2x3 experimental design was used, which consisted of processing methods (boiling, roasting, and microwave) and cooling at room temperature and 4 °C for 24 hours with 3 repetitions. Black potato flour was compared with the raw form, by assessing some parameters, namely Resistant Starch (RS), Slowly Digestible Starch (SDS), Rapidly Digestible Starch (RDS), and Glycemic Index (GI). Also, the analysis of total starch, moisture, and color was performed, hence raw black potatoes generally have 10% resistant starch (%wb). Different treatments of cooking and cooling had a significant effect (α = 0.05) on moisture content, total starch, RS, RDS, SDS, GI, brightness (L), and yellowness (b). Black potatoes subjected to the processing method followed by cooling had lower RDS and increased RS content. Furthermore, refrigeration at 4°C for 24 hours reduced the digestibility of black potato starch more than cooling at room temperature. Contrarily, microwaved black potato cooled at room temperature showed a higher digestion rate compared to the raw counterpart. Conclusively, processing followed by cooling reduces the GI and increases the RS content of Coleus tuberosus.

Using Dynamic Analysis for Compact Gear Design

1998 ◽  
Author(s):  
Ping-Hsun Lin ◽  
Hsiang Hsi Lin ◽  
Fred B. Oswald ◽  
Dennis P. Townsend
Keyword(s):  
Dynamic Response ◽  
Bending Strength ◽  
Three Dimensional ◽  
Spur Gear ◽  
Dynamic Factor ◽  
Operating Speed ◽  
Gear Design ◽  
Dynamic Factors ◽  
Speed Range ◽  
Response Change

Abstract This paper presents procedures for designing compact spur gear sets with the objective of minimizing the gear size. The allowable tooth stress and dynamic response are incorporated in the process to obtain a feasible design region. Various dynamic rating factors were investigated and evaluated. The constraints of contact stress limits and involute interference combined with the tooth bending strength provide the main criteria for this investigation. A three-dimensional design space involving the gear size, diametral pitch, and operating speed was developed to illustrate the optimal design of spur gear pairs. The study performed here indicates that as gears operate over a range of speeds, variations in the dynamic response change the required gear size in a trend that parallels the dynamic factor. The dynamic factors are strongly affected by the system natural frequencies. The peak values of the dynamic factor within the operating speed range significantly influence the optimal gear designs. The refined dynamic factor introduced in this study yields more compact designs than AGMA dynamic factors.

Hydrothermal synthesis of Co-doped In2S3 micropompons and their physical properties

2008 ◽  
Vol 23 (4) ◽  
pp. 917-923 ◽  
Author(s):  
Anuja Datta ◽  
Dibyendu Ganguli ◽  
Subhadra Chaudhuri
Keyword(s):  
Room Temperature ◽  
Lattice Structure ◽  
Blue Shift ◽  
Lattice Parameter ◽  
Host Lattice ◽  
Ultraviolet Emission ◽  
Paramagnetic Resonance ◽  
Optical Absorbance ◽  
Resonance Band ◽  
Co Doped

In2−xCoxS3 (x = 0 to 0.1) micropompons (diameters ∼3–4 μm) consisting of ∼10–15-nm-thick randomly self-assembled nanoflakes were synthesized hydrothermally. X-ray study indicated a steady variation of lattice parameter ratio up to 5% Co. Detailed investigations of the Co incorporation in In2S3 were carried out by optical absorbance, room temperature photoluminescence (PL), and electron paramagnetic resonance (EPR) studies. Significant blue shift in the absorbance spectra was noticed due to the crystal-field splitting of Co2+ ions in the host lattice structure. Unlike the visible emission found in undoped In2S3, PL spectra of the Co-doped samples were recognized by a strong ultraviolet emission peak at ∼335 nm, introduced by the t2g level of Co2+ ions, with maximum intensity for 5% Co. Room-temperature and low-temperature EPR spectra revealed octet paramagnetic bands up to 5% Co beyond which a single resonance band appeared.

scholarly journals Green Synthesis and Characterization of Gallium(III) Sulphide (α-Ga2S3) Nanoparicles at Room Temperature

Nano Hybrids ◽  
2014 ◽  
Vol 6 ◽  
pp. 37-46 ◽  
Author(s):  
Tansir Ahamad ◽  
Saad M. Alshehri
Keyword(s):  
Green Synthesis ◽  
Band Gap ◽  
Raman Spectra ◽  
Room Temperature ◽  
Optical Band Gap ◽  
Blue Shift ◽  
Synthesis And Characterization ◽  
Spectroscopic Techniques ◽  
Sodium Thiosulphate

Two different batches of Gallium (III) sulphide nanocrystals, (α-Ga2S3)1 and (α-Ga2S3)2 were synthesized at room temperature by the reaction of Gallium (III) chloride with sodium thiosulphate in water for 10 and 20 min respectively. The resultant nanoparticles were characterized by different spectroscopic techniques. TEM micrographs showed well-defined, close to hexagonal particles, and the lattice fringes in the HRTEM images confirmed their nanocrystalline nature. The sizes of (α-Ga2S3)1 and (α-Ga2S3)2 were 12 and 35 nm respectively with similar morphologies. Optical band gap energies (3.43 eV/3.41 eV) and photoluminescence peaks 635/641 nm (red shift) and 414/420 nm (blue shift) of the synthesized α-Ga2S3 nanocrystals suggest that they may be promising photocatalysts. Raman spectra for the α-Ga2S3, shows very sharp bands at 119, 135 and 148 cm-1 due to Ga-S2 scissoring.

Piping Seismic Stress Limits: A Critical Review

2002 ◽  
Author(s):  
Gerry C. Slagis
Keyword(s):  
Nonlinear Dynamic ◽  
Static Load ◽  
Dynamic Factor ◽  
Seismic Capacity ◽  
Strength Factor ◽  
Linear Elastic ◽  
Dynamic Factors ◽  
Load Limit ◽  
Potential Failure ◽  
Seismic Stress

Seismic stress limits for nuclear piping were published by the Section III code in 1994. Because of concerns on the technical bases for the rules, NRC has not approved their use. Modifications to the rules have been made in 2001. The 1994 seismic stress limits are reduced, and one type of joint now has a seismic stress limit that is less that the static load limit. A limit for seismic that is less than the limit for a static load contradicts the test data. Most of the technical concerns were valid. The 1994 rules are based on the premise that collapse is not a potential failure mode for a seismic event. However, collapse occurred in two of the EPRI component tests. Seismic margins in the component tests were overestimated. Revisions to the seismic margin data do not support the higher stress limits. A different approach has been taken to justify the 2001 rules. A probability approach is used where seismic capacity is related to a strength factor. The strength factor is based on the measured ultimate moment in the component tests. The capacity is the strength factor multiplied by a nonlinear dynamic factor. A small nonlinear dynamic factor is used because of concerns with off-resonance margin in stiff components. In contrast, the tests demonstrate large nonlinear dynamic factors. The intent of the new rules is to limit piping response to the SSE to the linear elastic range.

Controlled Synthesis of PbWO4 Crystals with Good Fluorescence Property by a Novel Duck Egg Membrane

2015 ◽  
Vol 33 ◽  
pp. 49-59
Author(s):  
Bao You Gong ◽  
Le Pan ◽  
Qing Feng Zhang ◽  
Hui Zhang ◽  
An Jian Xie ◽  
...  
Keyword(s):  
Outer Surface ◽  
Fluorescence Spectra ◽  
Room Temperature ◽  
Blue Shift ◽  
Biomimetic Synthesis ◽  
Reactant Concentration ◽  
Inner Surface ◽  
Egg Membrane ◽  
Duck Egg ◽  
Slight Blue Shift

PbWO4 crystals with different morphologies were readily induced by duck egg membrane via biomimetic synthesis at room temperature. The size and morphologies of the PbWO4 crystals could be controlled by outer or inner surface of duck egg membrane, the reactant concentration and the reaction time. The results show that spherical, flower-like and spindle-like crystals were obtained on the inner surface of membrane while rhombic, hexagon-like and chrysanthemum-like crystals were gained on the outer surface with the concentration of Pb2+ and WO42- increases. Room-temperature fluorescence spectra indicate the products on the inner surface of the duck egg membrane have a slight blue shift compared to that on the outer surface at the same condition. The PbWO4 crystals with small size obtained at a lower reactant concentration present a better fluorescence performance. The exploration of the reaction mechanism reveals that the interaction between Pb2+ ions and the proteins on the surface of duck egg membrane can make the conformation of the proteins more ordered. In general, the present synthesis route may be extended to prepare other inorganic functional micro-materials.

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