scholarly journals COMPARATIVE ANALYSIS OF THE BEHAVIOR OF WEAK ABSORPTION BANDS OF AMMONIA AT 552 AND 645 NM IN THE SPECTRUM OF JUPITER

2021 ◽  
Vol 3 (337) ◽  
pp. 148-155
Author(s):  
V.A. Filippov ◽  
V.D. Vdovichenko ◽  
A.M. Karimov
Keyword(s):  
Comparative Analysis ◽  
Absorption Bands ◽  
Weak Absorption

scholarly journals EXPRESS: Photoacoustic Detection of Weak Absorption Bands in Infrared Spectra of Calcite

2021 ◽  
pp. 000370282110092
Author(s):  
Stephen Campbell ◽  
Marisa Dusseault ◽  
Ben Xu ◽  
Kirk Michaelian ◽  
Kristin Poduska
Keyword(s):  
Infrared Spectra ◽  
Infrared Absorption ◽  
Driving Force ◽  
Theoretical Basis ◽  
Absorption Bands ◽  
Photoacoustic Detection ◽  
Weak Absorption ◽  
Rapid Scan ◽  
Isotopic Species ◽  
New Knowledge

Photoacoustic spectroscopic (PAS) detection of infrared absorption often produces spectra with enhanced intensities for weaker peaks, enabling the detection of features due to overtones and combinations, as well as less-abundant isotopic species. To illustrate this phenomenon, we present and discuss PAS infrared spectra of calcite (CaCO<sub>3</sub>). We use linearization of rapid-scan spectra, as well as comparing step-scan and rapid-scan spectra, to demonstrate that saturation is not the driving force behind these enhanced intensities. Our results point to a new knowledge gap, since a theoretical basis for the enhancement of these weak bands has not yet been developed.

Search for Weak Absorption Bands of Benzonitrile in the Near Ultraviolet

1952 ◽  
Vol 20 (11) ◽  
pp. 1821-1822 ◽  
Author(s):  
Robert C. Hirt ◽  
Frank T. King
Keyword(s):  
Absorption Bands ◽  
Weak Absorption ◽  
Near Ultraviolet

Optical properties of Cu− centres in NaCl crystals

1977 ◽  
Vol 55 (15) ◽  
pp. 1316-1321 ◽  
Author(s):  
Taiju Tsuboi
Keyword(s):  
Optical Properties ◽  
Spectral Range ◽  
Systematic Study ◽  
Vacuum Ultraviolet ◽  
Emission Spectra ◽  
Absorption Bands ◽  
Weak Absorption ◽  
Isoelectronic Series

For a systematic study of the isoelectronic series of s2-type centres, absorption, excitation and emission spectra of Cu− centres in NaCl crystals are investigated in the ultraviolet and vacuum ultraviolet spectral range at temperatures from 77 to 300 K. Two weak absorption bands were observed at 269 and 256 nm in addition to four bands at 288, 272, 232, and 189 nm which are assigned to the A, B, C and D bands of s2-type spectra, respectively, while only two emission bands peaking at 423 and 318 nm were detected. These results of Cu− centres are compared with those of the hitherto investigated s2-type centres.

scholarly journals Weak spectral features on (101995) Bennu from the OSIRIS-REx Visible and InfraRed Spectrometer

2020 ◽  
Vol 644 ◽  
pp. A148 ◽  
Author(s):  
A. A. Simon ◽  
H. H. Kaplan ◽  
E. Cloutis ◽  
V. E. Hamilton ◽  
C. Lantz ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Surface Shape ◽  
Spectral Features ◽  
Absorption Bands ◽  
Weak Absorption ◽  
Spectral Interpretation ◽  
Average Spectrum ◽  
Resource Identification ◽  
Infrared Spectrometer ◽  
Compositional Variations

Context. The NASA Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission has obtained thousands of spectra of asteroid (101955) Bennu with the OSIRIS-REx Visible and InfraRed Spectrometer. Aims. We present a spectral search for minor absorption bands and determine compositional variations on the surface of Bennu. Methods. Reflectance spectra with low and high spatial resolutions were analyzed for evidence of weak absorption bands. Spectra were also divided by a global average spectrum to isolate unique spectral features, and variations in the strongest band depths were mapped on a surface shape model. The global visible to near-IR spectrum of Bennu shows evidence of several weak absorption bands with depths of a few percent. Results. Several observed bands are consistent with phyllosilicates, and their distribution correlates with the stronger 2.74-μm hydration band. A 0.55-μm band is consistent with iron oxides and is deepest in the spectrally reddest areas on Bennu. The presence of hydrated phyllosilicates and iron oxides indicates substantial aqueous alteration in Bennu’s past. Conclusions. Bennu’s spectra are not identical to a limited set of carbonaceous chondrite spectra, possibly due to compositional properties and spatial scale differences; however, returned samples should contain a mixture of common chondrite materials.

The Influence of the Structural Organisation of Nitrile Butadiene Rubbers on their Vulcanisation

2017 ◽  
Vol 44 (8) ◽  
pp. 15-20
Author(s):  
L.V. Sokolova ◽  
N.A. Kichaev
Keyword(s):  
Comparative Analysis ◽  
Ir Spectroscopy ◽  
Acrylic Acid ◽  
Stearic Acid ◽  
Dynamic Viscosity ◽  
Absorption Bands ◽  
Shear Rates ◽  
Physicomechanical Characteristics ◽  
Structural Organisation ◽  
Acid Nitrile

A comparative analysis of features of the vulcanisation of nitrile butadiene rubbers containing 18 wt% units of acrylic acid nitrile with different distributions of the AAN units along the macromolecules is carried out. The content of cis-1,4-, trans-1,4-, and 1,2-units was determined by IR spectroscopy (Bruker Equinox 55 Fourier spectrometer) from the intensity of the 730, 970, and 910 cm−1 absorption bands respectively. The dynamic viscosity at temperatures of 85 and 130°C and at shear rates of 1.13–42.23 s−1 and also the vulcanisation kinetics were determined on an Alpha Technologies RPA 2000 unit. The physicomechanical characteristics were determined using a Gotech AI-3000 instrument. The vulcanising system contained sulphur, ZnO, stearic acid, and an accelerator. The influence of the content of stearic acid on the properties of the vulcanisates was studied, and it was shown that the rubbers investigated can be divided into three groups. The authors suggest that the vulcanisation parameters and the physicomechanical characteristics of the elastomers are most influenced by the size of the alternating unit nanoformations.

Polarimetric Observations of Red Variables: A Study of Gas and Particle Interactions

1979 ◽  
Vol 46 ◽  
pp. 386-408 ◽  
Author(s):  
G. V. Coyne ◽  
I. S. McLean
Keyword(s):  
Wavelength Dependence ◽  
Stellar Atmosphere ◽  
Molecular Absorption ◽  
Absorption Bands ◽  
Absorption And Emission ◽  
Mira Variables ◽  
Stellar Photosphere ◽  
Regular Variable ◽  
Red Supergiants ◽  
Balmer Lines

AbstractIn recent years the wavelength, dependence of the polarization in a number of Mira variables, semi-regular variables and red supergiants has been measured with resolutions between 0.3 and 300 A over the range 3300 to 11000 A. Variations are seen across molecular absorption bands, especially TiO bands, and across atomic absorption and emission lines, especially the Balmer lines. In most cases one can ignore or it is possible to eliminate the effects due to interstellar polarization, so that one can study the polarization mechanisms operating in the stellar atmosphere and environment. The stars Omicron Ceti. (Mira), V CVn (semi-regular variable) and Mu Cephei (M2 la), in addition to other stars similar to them, will be discussed in some detail.Models to explain the observed polarization consider that the continuum flux is polarized either by electron, molecular and/or grain scattering or by temperature variations and/or geometrical asymmetries over the stellar photosphere. This polarized radiation is affected by atomic and molecular absorption and emission processes at various geometric depths in the stellar atmosphere and envelope. High resolution spectropolarimetry promises, therefore, to be a power-rul tool for studying stratification effects in these stars.

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