scholarly journals The radiation properties of burning clouds of metal dust. 3. Modification of the emission spectrum

2021 ◽  
pp. 100-105
Author(s):  
V.G. Shevchuk ◽  
N.I. Poletaev ◽  
А.V. Nimich ◽  
G.L. Shyngarov
Keyword(s):  
Emission Spectrum ◽  
Emission Spectra ◽  
Combustion Products ◽  
Decomposition Temperature ◽  
Boron Compounds ◽  
Dust Clouds ◽  
Radiation Properties ◽  
Local Modification ◽  
Yellow Region ◽  
Metal Dust

In this work we studied the emission spectra of the combustion products of low-volume dust clouds (V = 5 L) from aluminum (ASD-4), as well as clouds from mixed compositions of aluminum with inorganic powdery oxidizing agents (NaNO3, NaCl, Na2CO3·10H2O, Sr(NO3)2, Ba(NO3)2, KNO3, CuSO4, CuSO4·10H2O) and combustible (B, AlB2, Cu). This article discusses the possibilities of purposeful modification of the emission spectrum of the base composition using various inert and optically active dispersed additives that shift the maximum of the emission spectrum of the fuel composition to the region of longer waves or cause a local change in the emission spectrum in the corresponding spectral regions. In the course of the experiments, it was revealed that the introduction of additives into the basic composition of dispersed fuel does not significantly change the dynamic characteristics of the suspension. However, the additives lead to a decrease in temperature (by about 100–200°K in the presence of an additive up to 25% by weight) and to a corresponding shift in the maximum of the radiation spectrum. The possibility of a significant local modification of the spectrum in the yellow region with the help of inorganic additives to the fuel of sodium salts with a low decomposition temperature (additives Na2CO3·10H2O) was shown experimentally. Boron additives and boron compounds (B, AlB2) leads to a significant increase in the luminosity of the flame in the green region of the spectrum with a maximum radiation in the range Δλ = 530 ÷ 580 nm. The article presents the lighting characteristics (luminous intensity, light sum) of large clouds (V ≥ 10 m3) of mixed compositions based on PAP-2 aluminum powder. It was found that the introduction of inorganic additives to the base fuel does not lead to a noticeable change in the lighting characteristics, but somewhat increases the time of the cloud glow both in the visible and infrared parts of the spectrum.

Searching for 3D effects in the optical, high spectral resolution emission spectrum of KELT-9b

2021 ◽  
Author(s):  
Lorenzo Pino ◽  
Matteo Brogi ◽  
Jean-Michel Désert ◽  
Emily Rauscher
Keyword(s):  
Emission Spectrum ◽  
Spectral Resolution ◽  
Planet Formation ◽  
Emission Spectra ◽  
Optical Emission ◽  
High Spectral Resolution ◽  
Optical Emission Spectrum ◽  
Hot Jupiters ◽  
Atmospheric Structure ◽  
3D Effects

<p>Ultra-hot Jupiters (UHJs; T<sub>eq</sub> ≥ 2500 K) are the hottest gaseous giants known. They emerged as ideal laboratories to test theories of atmospheric structure and its link to planet formation. Indeed, because of their high temperatures, (1) they likely host atmospheres in chemical equilibrium and (2) clouds do not form in their day-side. Their continuum, which can be measured with space-facilities, can be mostly attributed to H- opacity, an indicator of metallicity. From the ground, the high spectral resolution emission spectra of UHJs contains thousands of lines of refractory (Fe, Ti, TiO, …) and volatile species (OH, CO, …), whose combined atmospheric abundances could track planet formation history in a unique way. In this talk, we take a deeper look to the optical emission spectrum of KELT-9b covering planetary phases 0.25 - 0.75 (i.e. between secondary eclipse and quadrature), and search for the effect of atmospheric dynamics and three-dimensionality of the planet atmosphere on the resolved line profiles, in the context of a consolidated statistical framework. We discuss the suitability of the traditionally adopted 1D models to interprete phase-resolved observations of ultra-hot Jupiters, and the potential of this kind of observations to probe their 3D atmospheric structure and dynamics. Ultimately, understanding which factors affect the line-shape in UHJs will also lead to more accurate and more precise abundance measurements, opening a new window on exoplanet formation and evolution.</p>

scholarly journals Causes of Color in Minerals and Gemstones

2001 ◽  
Vol 9 (2) ◽  
pp. 14-17
Author(s):  
Paul F. Hlava
Keyword(s):  
Emission Spectrum ◽  
White Light ◽  
Emission Spectra ◽  
Light Sources ◽  
Physical Phenomena

The colors that one sees when looking at a mineral or gemstone are due to the response of that person's eye to the energies of the light, the emission spectrum of the illumination, and, most importantly, physical phenomena in the material that cause some colors to be absorbed while others are undisturbed or enhanced. It is beyond the scope of this article to do more than touch on the physiology of the eye that allows us to see colors. Likewise, we will not dwell on the emission spectra of various light sources. Rather, we will concentrate on the various ways in which materials, especially minerals and their heights of perfection, gemstones, produce color from white light.

Spectroanalytical Parameters of Fungal Metabolites. IV. Moniliformin

1974 ◽  
Vol 57 (6) ◽  
pp. 1392-1396 ◽  
Author(s):  
J A Lansden ◽  
R J Clarkson ◽  
W C Neely ◽  
R J Cole ◽  
J W Kirksey
Keyword(s):  
Low Temperature ◽  
Aqueous Solutions ◽  
Ambient Temperature ◽  
Emission Spectrum ◽  
Potassium Salt ◽  
Emission Spectra ◽  
Fungal Metabolites ◽  
Fungal Metabolite ◽  
Fluorescence Excitation ◽  
Phosphorescence Emission

Abstract The spectral data for a novel fungal metabolite, moniliformin (potassium salt of 1-hydroxycyclobut- 1-ene-3,4-dione), are reported. The corrected ambient temperature fluorescence excitation and emission spectra are given and the quantum efficiency is calculated to be 5.32 × 10舓3. The uncorrected low temperature phosphorescence emission spectrum and lifetime are also reported. Other physical data are given to support spectral evidence that the molecule exists as a dimer in aqueous solutions.

scholarly journals Irradiance and Radiant Exposures Delivered by LED Light-Curing Units Used by a Left and Right-Handed Operator

2018 ◽  
Vol 29 (3) ◽  
pp. 282-289 ◽  
Author(s):  
Carlos José Soares ◽  
Gabriel Felipe de Bragança ◽  
Renata Afonso da Silva Pereira ◽  
Monise de Paula Rodrigues ◽  
Stella Sueli Lourenço Braga ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Light Emitting Diode ◽  
Resin Composite ◽  
Emission Spectra ◽  
Hand Preference ◽  
Second Molar ◽  
Left Hand ◽  
Radiant Exposure ◽  
Light Curing ◽  
The Right

Abstract The combination of the restoration location, the hand preference of the operator using the light-curing unit (LCU), and the design of the LCU all can have an impact on the amount of the light delivered to the restoration. To evaluate the effect of left-handed or right-handed users, the position of the operator (dentist or assistant), and the LCU design on the irradiance, radiant exposure and emission spectrum delivered to the same posterior tooth. Two light emitting diode (LED) LCUs were tested: an angulated monowave LCU Radii-Cal (SDI, Victoria, Australia) and a straight aligned multi-peak LCU Valo Cordless (Ultradent, South Jordan, UT, USA). The irradiance values (mW/cm2), radiant exposure (J/cm2) and emission spectrum were measured using a sensor in maxillary left second molar tooth. The irradiance and radiant exposure were analyzed using three-way ANOVA followed by Tukey test (a=0.05). The emission spectra (nm) were analyzed descriptively. The interaction between LCU design, operator position, and hand preference significantly influenced the irradiance and radiant exposure (P<0.001). In all cases, Valo delivered significantly higher irradiance than Radii-Cal. The handedness and the operator position affected the irradiance and radiant exposure delivered from Valo. Operator position and access affect the irradiance and radiant exposure delivered to the maxillary left second molar. The irradiance and radiant exposure can be greater when a right-hand operator is positioned on the right side of the chair and a left-hand operator is positioned on the left side of the chair. This may result in better resin composite polymerization.

scholarly journals Formation of the X-ray line emission spectrum of excimer laser-produced plasmas

1998 ◽  
Vol 16 (1) ◽  
pp. 61-70 ◽  
Author(s):  
A. Magunov ◽  
A. Faenov ◽  
I. Skobelev ◽  
T. Pikuz ◽  
D. Batani ◽  
...  
Keyword(s):  
Experimental Data ◽  
Laser Radiation ◽  
Laser Pulse ◽  
Emission Spectrum ◽  
Pulse Train ◽  
Line Emission ◽  
Emission Spectra ◽  
Theoretical Modelling ◽  
Xecl Laser ◽  
X Ray

Time- and space-integrated emission spectra measurements have been performed in plasma produced by 308 nm wavelength XeCl laser radiation (IL = (4–10)·1012 W/cm2, τ = 10 ns) and by 248 nm wavelength KrF laser pulse train radiation (IL = 5·1015 W/cm2, τ = 7 ps, 16 pulses in train) on CF2 plane target. Theoretical modelling of Lyman series and He-like ion resonance series of fluorine and its fit of experimental data show considerable differences in the absorption of laser radiation in the two plasmas.

scholarly journals Tyrosine and tyrosinate fluorescence of pig intestinal Ca2+-binding protein

1987 ◽  
Vol 243 (2) ◽  
pp. 611-615 ◽  
Author(s):  
J D J O'Neil ◽  
T Hofmann
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Emission Spectrum ◽  
Hydroxy Group ◽  
Binding Proteins ◽  
Binding Protein ◽  
Emission Spectra ◽  
Difference Spectrum ◽  
Tyrosine Residue

The single tyrosine residue in both pig and cow intestinal Ca2+-binding proteins fluoresces at 303 nm although the crystal structure of the cow protein shows a hydrogen bond between the hydroxy group of the tyrosine and glutamate-38 [Szebenyi & Moffat (1986) J. Biol. Chem. 261, 8761-8777]. The latter interaction suggests that tyrosinate fluorescence should dominate the emission spectra of these proteins. A fluorescence difference spectrum, produced by subtracting the spectrum of free tyrosine from the spectrum of the protein, gives a peak at 334 nm due to ionized tyrosine. That this component of the emission spectrum is not due to a tryptophan-containing contaminant is shown by its elimination when the protein is denatured by guanidine and when glutamate-38 is protonated. We conclude that, in solution, the tyrosine residue in this protein interacts occasionally with glutamate-38 but that a permanent hydrogen bond is not formed.

scholarly journals Characterizing the Atmospheres of Hot Jupiters: From Spectra to Multi-Color Maps

2008 ◽  
Vol 4 (S253) ◽  
pp. 255-261
Author(s):  
Heather A. Knutson
Keyword(s):  
Emission Spectrum ◽  
Inversion Layer ◽  
Emission Spectra ◽  
Phase Curve ◽  
Hot Jupiters ◽  
Thermal Phase ◽  
Additional Support ◽  
Temperature Inversions ◽  
The Relationship ◽  
Hot Jupiter

AbstractWe present new observations of the emission spectrum of the hot Jupiter TrES-4 designed to test the theory that the presence of temperature inversions in the atmospheres of these planets are correlated with the amount of radiation received by the planet. Our observations reveal that TrES-4 has an emission spectrum similar to that of HD 209458b, which requires the presence of an inversion layer high in the atmosphere and water emission bands in order to explain the observed features, providing additional support for that theory. We also present new observations of the thermal phase curve of HD 189733b at 24 μm, which we combine with our previous observations at 8 μm to examine how circulation in this planet's atmosphere varies as a function of depth. We discuss the relationship between the strength of the day-night circulation on both planets and their other observable properties, in particular their emission spectra.

Barium Exhaust Spectrum during the Expansion of Combustion Products through a Nozzle into Vacuum

1971 ◽  
Vol 26 (7) ◽  
pp. 1147-1155 ◽  
Author(s):  
Cristiano Batalli-Cosmovici ◽  
Karl-Wolfgang Michel
Keyword(s):  
Emission Spectrum ◽  
Brightness Temperature ◽  
Particle Temperature ◽  
Combustion Products ◽  
Fast Process ◽  
Two Phase ◽  
Apparent Color ◽  
Non Equilibrium

AbstractThe emission spectrum from a two-phase nozzle jet, consisting of combustion products of Ba and CuO, revealed that non-equilibrium amounts of excited and ionized Ba atoms occur only during the nozzle starting transient. Traces of BaO-and Cu2-molecules could be identified in the cold outer parts of the jet. The particle temperature near the nozzle, derived from novel measurements of apparent color and brightness temperature, confirms LTE calculations if the vaporization of excess Ba is taken to be a fast process.

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