The aggregation of copper phthalocyanine dyes

1972 ◽  
Vol 25 (8) ◽  
pp. 1661 ◽  
Author(s):  
LC Gruen
Keyword(s):  
Dielectric Constant ◽  
Ionic Strength ◽  
Absorption Spectra ◽  
Copper Phthalocyanine ◽  
Reactive Dyes ◽  
The Other ◽  
Visible Absorption ◽  
Monomeric Species ◽  
Other Hand ◽  
Phthalocyanine Dyes

The visible absorption spectra of two reactive dyes based on the copper phthalocyanine chromophore have been investigated as a function of concentration, temperature, pH, ionic strength, and solvent. The persistence of isosbestic points indicates that an equilibrium exists, over the concentration range investigated, between two forms of the dye only, namely dimer and monomer. The addition of urea exerts a relatively small disaggregating influence on this equilibrium. On the other hand decrease in dielectric constant substantially changes the equilibrium in favour of the monomeric species.

The aggregation and reaction with oxygen of the tetrasodium salt of cobalt phthalocyanine-4,4',4'',4'''-tetrasulphonic acid

1973 ◽  
Vol 26 (2) ◽  
pp. 319 ◽  
Author(s):  
LC Gruen ◽  
RJ Blagrove
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Molecular Oxygen ◽  
Absorption Spectra ◽  
Alkaline Solution ◽  
Cobalt Phthalocyanine ◽  
Visible Absorption ◽  
Reversible Addition ◽  
Dimeric Form ◽  
Low Ionic Strength

The reversible addition of molecular oxygen to the tetrasodium salt of cobalt phthalocyanine-4,4?,4?,4??-tetrasulphonic acid in aqueous solution has been confirmed. Visible absorption spectra of the monomeric and dimeric species and of the oxygen adduct have been determined. A monomer-dimer system prevails at neutral pH, low ionic strength, and low dye concentrations. The oxygen adduct and the dimeric form of the dye predominate in alkaline solution.

Effect of the Annealing Temperature on Dielectric Properties of Bi1.5Zn1.0Nb1.5O7 Films Prepared by MOCVD

2008 ◽  
Vol 388 ◽  
pp. 175-178
Author(s):  
Hiroshi Funakubo ◽  
Shingo Okaura ◽  
Muneyasu Suzuki ◽  
Hiroshi Uchida ◽  
Seiichiro Koda
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Temperature Coefficient ◽  
Annealing Temperature ◽  
Relative Dielectric Constant ◽  
Fused Silica ◽  
The Other ◽  
Other Hand ◽  
Silica Substrates

Effect of annealing temperature on the dielectric properties of Bi1.5Zn1.0Nb1.5O7 films prepared on (111)Pt//(001)Al2O3 and (111)Pt/fused silica substrates by MOCVD was investigated. The tunability and the inverse of the dielectric loss [1/ (tan )] increased with increasing annealing temperature. Relative dielectric constant and temperature coefficient of the capacitance (TCC) increased with the crystallinity of the films. On the other hand, (1/tan ) was independent of the crystallinity of the films, but was dramatically increased by the annealing.

Complexes moléculaires d'hétérocycles soufrés et oxygénés. Étude spectrophotométrique de bandes de transfert de charge multiples

1982 ◽  
Vol 60 (7) ◽  
pp. 862-871 ◽  
Author(s):  
Jean-Paul Canselier ◽  
Serge Domenech ◽  
Štefan Stankovsky ◽  
Sabine Gautier
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Molecular Complexes ◽  
The Other ◽  
Ionization Potentials ◽  
Nonpolar Solvents ◽  
Other Hand ◽  
The One

As with benzenoid donors, the electronic absorption spectra of the molecular complexes of simple or condensed sulfur or oxygen-containing five-membered heterocycles with TCNE (or DDQ) often show two charge-transfer bands. In many cases, the knowledge of the actual frequencies requires a technique of resolution. The results so obtained are correlated with the ionization potentials of donors on the one hand, and the refractivity of nonpolar solvents on the other hand.

Stability of fast elaborated small CdS quantum dots

2011 ◽  
Vol 1286 ◽  
Author(s):  
M. Fregnaux ◽  
S. Dalmasso ◽  
J.-J. Gaumet ◽  
J.-P. Laurenti
Keyword(s):  
Absorption Spectra ◽  
Broad Band ◽  
Surface States ◽  
The Other ◽  
Cds Quantum Dots ◽  
Other Hand ◽  
Direct Exposure ◽  
Single Source Precursor ◽  
Excitonic Transition ◽  
Excitonic Emission

ABSTRACTSmall size CdS QDs were synthesized by (i) the single source precursor methodology and by (ii) the microwave synthetic route. The consequences of CdS QD direct exposure to air for a period of 7 days were investigated by following the evolution of the photoluminescence (PL) and absortion spectra. For QDs obtained by (i), the excitonic emission band (3.0 ‑ 3.1 eV) decreases in intensity, relatively to the low energy one (2.2 ‑ 2.5 eV) tentatively associated to midgap surface states. This suggests arising of new recombination path(s) associated to degradations during aging, possibly an oxidative formation of a CdO surface layer. On the other hand, no significant change is observed in the absorption spectra. For QDs obtained by (ii), no degradation is revealed by the PL spectra which remain unchanged. On the other hand, the absorption spectra are dominated by an unexplained broad band around 3.6 eV which tends to hide the fundamental excitonic transition one and increases in intensity with aging.

Electrical Properties and Polarization Reversal in (Li,Na)NbO3 Lead-Free Piezoelectric Ceramics

2011 ◽  
Vol 485 ◽  
pp. 69-72 ◽  
Author(s):  
Takayuki Ohashi ◽  
Rintaro Aoyagi ◽  
Masaki Maeda ◽  
Makoto Iwata
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Frequency Dependence ◽  
Piezoelectric Ceramics ◽  
Polarization Switching ◽  
Coupling Factor ◽  
The Other ◽  
Lead Free ◽  
Polarization Reversal ◽  
Other Hand

In this study, the relationships between the electrical properties and polarization switching of lead-free (Li0.06Na0.94)NbO3 (LNN6) ceramics were investigated. The electrical properties of stoichiometric LNN6 did not change with polarization switching. On the other hand, the frequency dependence of the impedance of Na-deficient LNN decreased with polarization switching, and the coupling factor kp, the piezoelecric constant d33 and the dielectric constant ε33T/ε0 decreased with polarization switching. Moreover, the dielectric curve of Na-deficient LNN6 after 10 switchings showed peaks at approximately 330, 400 and 500 °C

Observations on the colouring of pink and green zoned tourmaline

1953 ◽  
Vol 30 (220) ◽  
pp. 26-38 ◽  
Author(s):  
J. E. S. Bradley ◽  
Olive Bradley
Keyword(s):  
Absorption Spectra ◽  
Absorption Spectroscopy ◽  
Emission Spectra ◽  
The Other ◽  
Other Hand

This investigation was concerned with two aspects of the colour-zoning in tourmaline: firstly, the origin of the green and pink colours ; secondly, the reason for the apparent incompatibility of these two forms. Much of the previous work on the colour of tourmaline has involved the use of emission spectra. This method provides information as to which elements are present; it does not, of course, indicate which of the twenty or so elements identified is responsible for the colour, although it may be possible to infer this. Absorption spectra, on the other hand, are directly concerned with colour. They have been employed quite extensively in Germany, and more recently in Russia, but the earlier data and instruments were often inadequate. The last decade has seen marked improvements in the technique of absorption spectroscopy, particularly in the development of photo-electric methods for the quantitative recording of spectra, and the method is likely to prove one of increasing value.

Mechanism of the formation of halogen monoxides during flash photolysis of halogen + oxygen mixtures

1963 ◽  
Vol 271 (1346) ◽  
pp. 289-295 ◽  
Keyword(s):  
Absorption Spectra ◽  
Flash Photolysis ◽  
Radiant Energy ◽  
The Other ◽  
Other Hand ◽  
Absorption Of Light ◽  
Oxygen Atoms

The mechanism of the formation of BrO and CIO in the flash photolysis of halogen + oxygen mixtures was investigated. It was found that the predominant mechanism for the production of BrO (about 90 % in our experiments) involves the absorption of light by the oxygen molecules. The O* 2 or the oxygen atoms produced create ozone, which in turn produces BrO when photolyzed. It is possible that some of O* 2 or O produces BrO directly and not via an ozone intermediate. About 10 % of the BrO is produced when two quanta of radiant energy are absorbed by the Br 2 molecule. The highly energetic molecule formed in this way is capable of breaking the O—O bond and forming BrO. The reaction between the excited Br atoms and O 2 , suggested by Durie & Bamsey (1958), does not occur. It seems likely that IO is formed by a mechanism similar to that of BrO. On the other hand, CIO is produced predominantly in a reaction of Cl( 2 P ) atoms with O 2 , as suggested by Porter & Wright (1953). Chlorine and bromine absorption spectra were measured down to 1880 and 1930 Å, respectively.

scholarly journals On Dielectric Constant and Enzymatic Kinetics

1962 ◽  
Vol 45 (4) ◽  
pp. 21-30 ◽  
Author(s):  
M. Castañeda-Agulló ◽  
Luz M. del Castillo
Keyword(s):  
Dielectric Constant ◽  
Ionic Strength ◽  
Linear Relationship ◽  
Salt Effect ◽  
The Other ◽  
Ion Structure ◽  
Glycine Solution ◽  
Enzymatic Kinetics ◽  
The One ◽  
Low Ionic Strength

A study was made on the effect of glycine on systems involving trypsin and BAEE1 or TSAME on the one hand, or α-chymotrypsin with any of the substrates BAEE, TEE, or PEE, on the other. In all cases there was a linear relationship between the rate logarithm and the reciprocal of the dielectric constant of the glycine solution. The slopes were positive in the reactions of trypsin. In those catalyzed by α-chymotrypsin, the slopes were positive at pH 6.5 or lower, and negative at pH 7.5. However, the effects of glycine differ quantitatively from those of urea or other solvents. The presence of salt modifies somewhat the glycine effects. A low ionic strength increases the effect of glycine on trypsin, but if the inhibition caused by the ionic strength is relatively strong, the addition of glycine partially neutralizes the salt effect. Addition of salt to systems containing α-chymotrypsin always resulted in a diminished effect of glycine. An attempt is made to interpret the anomalies of glycine effects on the basis of its dipolar ion structure.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

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