In Situ Spectral Properties (Reflectance and Fluorescence) of Benthic Substrates and Organisms

1997 ◽  
Author(s):  
Charles Mazel
Keyword(s):  
Spectral Properties

scholarly journals Characterisation and improvement of <i>j</i>(O<sup>1</sup>D) filter radiometers

2016 ◽  
Author(s):  
Birger Bohn ◽  
Dwayne E. Heard ◽  
Nikolaos Mihalopoulos ◽  
Christian Plass-Dülmer ◽  
Rainer Schmitt ◽  
...  
Keyword(s):  
Cross Sections ◽  
Spectral Properties ◽  
Solar Spectrum ◽  
Field Measurements ◽  
Correction Method ◽  
Quantum Yields ◽  
Photolysis Frequencies ◽  
Filter Radiometer ◽  
Improved Performance

Abstract. Atmospheric O3 → O(1D) photolysis frequencies j(O1D) are crucial parameters for atmospheric photochemistry because of their importance for primary OH formation. Filter radiometers have been used for many years for in-situ field measurements of j(O1D). Typically the relationship between the output of the instruments and j(O1D) is non-linear because of changes in the shape of the solar spectrum dependent on solar zenith angles and total ozone columns. These non-linearities can be compensated by a correction method based on laboratory measurements of the spectral sensitivity of the filter radiometer and simulated solar actinic flux density spectra. Although this correction is routinely applied, the results of a previous field comparison study of several filter radiometers revealed that some corrections were inadequate. In this work the spectral characterisations of seven instruments were revised and the correction procedures were updated and harmonized considering recent recommendations of absorption cross sections and quantum yields of the photolysis process O3 → O(1D). Previous inconsistencies were largely removed using these procedures. In addition, optical interference filters were replaced to improve the spectral properties of the instruments. Successive determinations of spectral sensitivities and field comparisons of the modified instruments with a spectroradiometer reference confirmed the improved performance. Overall, filter radiometers remain a low-maintenance alternative of spectroradiometers for accurate measurements of j(O1D) provided their spectral properties are known and potential drifts in sensitivities are monitored by regular calibrations with standard lamps or reference instruments.

scholarly journals Characterisation and improvement of <i>j</i>(O<sup>1</sup>D) filter radiometers

2016 ◽  
Vol 9 (7) ◽  
pp. 3455-3466 ◽  
Author(s):  
Birger Bohn ◽  
Dwayne E. Heard ◽  
Nikolaos Mihalopoulos ◽  
Christian Plass-Dülmer ◽  
Rainer Schmitt ◽  
...  
Keyword(s):  
Cross Sections ◽  
Spectral Properties ◽  
Solar Spectrum ◽  
Field Measurements ◽  
Correction Method ◽  
Quantum Yields ◽  
Photolysis Frequencies ◽  
Filter Radiometer ◽  
Improved Performance

Abstract. Atmospheric O3 →  O(1D) photolysis frequencies j(O1D) are crucial parameters for atmospheric photochemistry because of their importance for primary OH formation. Filter radiometers have been used for many years for in situ field measurements of j(O1D). Typically the relationship between the output of the instruments and j(O1D) is non-linear because of changes in the shape of the solar spectrum dependent on solar zenith angles and total ozone columns. These non-linearities can be compensated for by a correction method based on laboratory measurements of the spectral sensitivity of the filter radiometer and simulated solar actinic flux density spectra. Although this correction is routinely applied, the results of a previous field comparison study of several filter radiometers revealed that some corrections were inadequate. In this work the spectral characterisations of seven instruments were revised, and the correction procedures were updated and harmonised considering recent recommendations of absorption cross sections and quantum yields of the photolysis process O3 →  O(1D). Previous inconsistencies were largely removed using these procedures. In addition, optical interference filters were replaced to improve the spectral properties of the instruments. Successive determinations of spectral sensitivities and field comparisons of the modified instruments with a spectroradiometer reference confirmed the improved performance. Overall, filter radiometers remain a low-maintenance alternative of spectroradiometers for accurate measurements of j(O1D) provided their spectral properties are known and potential drifts in sensitivities are monitored by regular calibrations with standard lamps or reference instruments.

scholarly journals Spectral Properties of Coniferous Forests: A Review of In Situ and Laboratory Measurements

2018 ◽  
Vol 10 (2) ◽  
pp. 207 ◽  
Author(s):  
Miina Rautiainen ◽  
Petr Lukeš ◽  
Lucie Homolová ◽  
Aarne Hovi ◽  
Jan Pisek ◽  
...  
Keyword(s):  
Spectral Properties ◽  
Coniferous Forests ◽  
Laboratory Measurements

Synthesis, characterization and spectroscopic properties of new fluorescent 7,8-dihexyloxy-3-(4-oxyphenyl)coumarin substituted phthalocyanines

2009 ◽  
Vol 13 (06) ◽  
pp. 691-701 ◽  
Author(s):  
Meryem Çamur ◽  
Ali Rıza Özkaya ◽  
Mustafa Bulut
Keyword(s):  
Cyclic Voltammetry ◽  
Spectral Data ◽  
Electronic Absorption ◽  
Elemental Analysis ◽  
Spectral Properties ◽  
Spectroscopic Properties ◽  
Redox Behavior ◽  
Metal Free ◽  
The Difference

The synthesis of metal-free and metallophthalocyanines ( M = Zn , Co ) obtained from 7,8-dihexyloxy-3-[p-(3',4'-dicyanophenoxy)phenyl]coumarin are described. The newly prepared compounds have been characterized by elemental analysis, IR, NMR, mass and UV-vis spectral data. Their electronic absorption and fluorescence spectral properties are reported. Cyclic voltammetry of the compounds have also been studied. In situ spectroelectrochemistry of the Co(II) complex in THF and DCM is included to identify the difference in its redox behavior, as compared with other complexes.

The Synthesis of the Dimer and Trimer Ether-Linked Components of Hematoporphyrin Derivative

1990 ◽  
Vol 43 (11) ◽  
pp. 1889 ◽  
Author(s):  
CJ Byrne ◽  
IK Morris ◽  
AD Ward
Keyword(s):  
Spectral Properties ◽  
Hydrogen Bromide ◽  
Coupling Reaction ◽  
Side Chain ◽  
Side Chains ◽  
Hematoporphyrin Derivative ◽  
Acetyl Group ◽  
Porphyrin Dimer

The preparation is described of all of the likely dimer and trimer ether-linked components of the anticancer material known as hematoporphyrin derivative. The hydroxyethyl side chain of one porphyrin, related to hematoporphyrin, reacts readily with a bromoethyl system derived from the same, or similar, hematoporphyrin -derived porphyrin to form a diporphyrin ether. The coupling reaction can be controlled to occur in situ, allowing the preparation of a symmetrical ether-linked dimer , or separately to provide an asymmetrically substituted porphyrin dimer . The bromoethyl groups can be formed from either the hydroxyethyl groups or, more slowly, from a vinyl side chain by using hydrogen bromide in dichloromethane. Ether-linked porphyrin trimers can be prepared by reacting a dibromoethyl system with 2 equiv. of a hydroxyethyl -containing porphyrin or by further reaction of an initially formed dimer. Hydroxyethyl side chains in the dimers and trimers are best obtained by reduction of an acetyl group. Some spectral properties of the products are described.

scholarly journals Synthesis, structure, thermal decomposition and spectral properties of neutral [Fe(bpta)2(etOH)2(NCS)2]

2015 ◽  
Vol 8 (1) ◽  
pp. 78-85
Author(s):  
Zuzana Lukačovičová ◽  
Róbert Uhrecký ◽  
Ján Moncoľ ◽  
Darina Lackováa ◽  
Iveta Ondrejkovičová ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Infrared Spectroscopy ◽  
Structural Analysis ◽  
Spectral Properties ◽  
Ethanol Solution ◽  
Single Crystal Diffraction ◽  
Triclinic Space Group ◽  
X Ray

Abstract The new iron(II) complex [Fe(bpta)2(EtOH)2(NCS)2] (bpta = 3,3’-(1,2,4-thiadiazole-3,5-diyl) dipyridine; EtOH = ethanol) has been prepared by refluxing Fe(NCS)3 or Fe(NCS)2 with thionicotinamide in an ethanol solution and characterized by elemental analysis, infrared spectroscopy, thermal decomposition and X-ray structural analysis. The characterized compound is a mixture of three regioisomers resulting from differential coordination by the 3- and 5-position 2-pyridyl groups. The bpta ligand was generated in situ by the oxidation dimerization of thionicotinamide. X-ray single-crystal diffraction revealed that the crystal structure is centrosymmetric and the complex crystallizes in the triclinic space group P-1. The iron(II) atom lies in the centre of symmetry and it is octahedrally coordinated by two nitrogen atoms from two thiocyanate anions and two oxygen atoms from ethanol molecules in the equatorial plane and two nitrogen atoms of pyridine rings from two bpta ligands in the axial positions. This complex represents the second example of metal complex with bpta.

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

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