The Structure of Polyisoprenes. V. Ultraviolet Absorption Spectra of Certain Carbalkoxy-Substituted 1,5-Dienes, and the Charge-Resonance Spectra of Glutaconic Ester Enolate Ions

1946 ◽  
Vol 19 (1) ◽  
pp. 23-33
Author(s):  
L. Bateman ◽  
H. P. Koch
Keyword(s):  
Absorption Band ◽  
Absorption Spectra ◽  
Special Interest ◽  
Crystalline State ◽  
Marked Change ◽  
Cyanine Dyes ◽  
Structural Type ◽  
Wave Absorption ◽  
Long Wave ◽  
Ester Enolate

Abstract Spectral evidence supports the conclusion reached in Part IV that ring-chain mesomerism in methyl and ethyl Δ1,5-hexadiene-l,1,3,3,4,4,6,6-octacarboxylates is nonexistent in solution, just as in the crystalline state. The data are not inconsistent with chain hyperconjugation in these molecules. The marked change in structural type that follows the addition of one molecule of hydrogen or hydrolytic reagent has been verified spectrographically. The spectra of methyl and ethyl α,γ-dicarboxyglutaconic esters and their sodium and cupric derivatives have been measured in various solvents, and their tautomeric behavior compared with that of other keto-enols. Of special interest is the intense long-wave absorption band of the enolate ions, which are recognized as simple structural analogs of the cyanine dyes giving rise to similar charge-resonance spectra. A preliminary comment is made on the present accepted structure of ethyl 6-ethoxy-α-pyrone-3:5-dicarboxylate.

scholarly journals Ethyne Functionalized Meso-Phenothiazinyl-Phenyl-Porphyrins: Synthesis and Optical Properties of Free Base Versus Protonated Species

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4546
Author(s):  
Eva Molnar ◽  
Emese Gál ◽  
Luiza Găină ◽  
Castelia Cristea ◽  
Luminița Silaghi-Dumitrescu
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Photophysical Properties ◽  
Bathochromic Shift ◽  
Fluorescence Emission ◽  
Soret Band ◽  
Quantum Yields ◽  
Free Base ◽  
Wave Absorption ◽  
Long Wave

Synthesis, structural characterization and photophysical properties for a series of new trans-A2B2- and A3B-type ethynyl functionalized meso-phenothiazinyl-phenyl porphyrin derivatives are described. The new compounds displayed the characteristic porphyrin absorption spectra slightly modified by weak auxochromic effects of the substituents and fluorescence emission in the range of 651–659 nm with 11–25% quantum yields. The changes recorded in the UV-vis absorption spectra in the presence of trifluoroacetic acid (TFA) are consistent with the protonation of the two internal nitrogen atoms of the free-base porphyrin (19 nm bathochromic shift of the strong Soret band and one long wave absorption maxima situated in the range of 665–695 nm). Protonation of the phenothiazine substituents required increased amounts of TFA and produced a distinct hypsochromic shift of the long wave absorption maxima. The density functional theory (DFT) calculations of a porphyrin dication pointed out a saddle-distorted porphyrin ring as the ground-state geometry.

On the Determination of Transition-Moment Directions from Absorption Anisotropy Measurements

1987 ◽  
Vol 42 (6) ◽  
pp. 617-621 ◽  
Author(s):  
A. Kawski ◽  
Z. Gryczyński
Keyword(s):  
Absorption Band ◽  
Polymer Film ◽  
Stretch Ratio ◽  
Transition Moment ◽  
Molecular Axis ◽  
Small Deviations ◽  
Wave Absorption ◽  
Long Wave ◽  
Absolute Transition

A formula is derived for the absorption anisotropy K = (A∥ - A⊥) / (A∥ + 2A⊥ ) (where A∥ and A⊥ are the absorbances parallel and perpendicular to the stretching direction of the polymer film, respectively) as a function of the stretch ratio, Rs, of the film and the angle φ between the absorption transition moment direction and the long axis of a prolate molecule. Employing this relation, absolute transition moment directions (the angles φ) were determined experimentally for the following compounds: 1.8-diphenyloctatetraene (DPO), 1,6-diphenylhexatriene (DPH), 1.4-diphenylbutadiene (DPB), 4-dimethylamino-4'-nitrostilbene (DNS), 4-dimethylamino- 4'-chlorostilbene (DCIS) and p-terphenyl (TP). The directions were found to be along the long molecular axis in the long-wave absorption band. Small deviations of the angles obtained from (φ= 0°, which were of the order of several degrees, are due to the incomplete linearity of the molecules under investigation.

scholarly journals On the Determination of Transition-Moment Directions from Emission Anisotropy Measurements

1986 ◽  
Vol 41 (10) ◽  
pp. 1195-1199 ◽  
Author(s):  
A. Kawski ◽  
Z. Gryczyński
Keyword(s):  
Absorption Band ◽  
Polymer Film ◽  
Transition Moment ◽  
Emission Anisotropy ◽  
Wave Absorption ◽  
Long Wave ◽  
Linear Trans

Based on the theory of photoluminescence polarization, a description of the determination of transition-moment directions in luminescent molecules oriented in a stretched polymer film is given. This method is applied to the linear trans-diphenylpolyenes (C2h symmetry): 1,8-diphenyloctatetraene (DPO ), 1,6-diphenylhexatriene (DPH) and 1,4-diphenylbutadiene (DPB). The same transition moment polarized along the long axis o f DPO , DPH and DPB is responsible for absorption and fluorescence (β ≈ 0), when exciting in the long wave absorption band. The results are compared with relevant data obtained from dichroism measurements.

INFLUENCE OF THE THICKNESS OF THE n-Si SUBSTRATE AND ITS DOPING LEVEL ON THE ABSORBING PROPERTIES OF SILICON PLASMON STRUCTURES IN THE INFRARED RANGE

2021 ◽  
Vol 88 (6) ◽  
pp. 887-894
Author(s):  
A. I. Mukhammad ◽  
P. I. Gaiduk
Keyword(s):  
Surface Layer ◽  
Absorption Band ◽  
Absorption Spectra ◽  
Doping Level ◽  
Phase Synchronization ◽  
Dispersion Relations ◽  
Infrared Range ◽  
Si Substrate ◽  
Significant Difference ◽  
Dielectric Interfaces

The absorption spectra of Si/SiO2/Si3N4/Si+ and Si/SiO2/Si+ structures with an island surface layer are calculated using the finite difference time domain method. The absorption spectra were modeled depending on the thickness of the substrate and its doping level. It was found that the thickness of the i-Si substrate does not affect the overall absorption of the structure. At the same time, an increase in the thickness of the n-Si substrate leads to an expansion of the absorption band with an intensity of more than 70%. It is established that the doping level of the substrate affects the absorption value of the structures and bandwidth with an absorption value above 80%. It is shown that a wide absorption band with intensity of more than 80% occurs at the doping level of the substrate in the range of 2 . 1019—5 . 1019 cm–3. Dispersion relations in the Si+/SiO2/Si+ structure with an unstructured surface layer are obtained. These dispersion relations may indicate the existence of plasmon oscillations in the system. It is established that a violation of the phase synchronization of the modes at both Si/dielectric interfaces at a significant difference between the doping levels of the substrate and the surface layer can lead to a decrease in the absorption.

scholarly journals Локализованные экситоны в спектре оптического поглощения оксида цинка, легированного марганцем

2019 ◽  
Vol 61 (5) ◽  
pp. 817
Author(s):  
В.И. Соколов ◽  
Н.Б. Груздев ◽  
В.А. Важенин ◽  
А.В. Фокин ◽  
А.В. Дружинин
Keyword(s):  
Zinc Oxide ◽  
Charge Transfer ◽  
Absorption Band ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Polarized Light ◽  
Threshold Energy ◽  
Impurity Absorption ◽  
Charge Transfer Transitions ◽  
Long Time

AbstractThe results of the study of optical absorption and EPR signals of single crystals of zinc oxide doped with manganese are presented. A broad impurity absorption band with the threshold energy about 2.1 eV, which was treated as a result of charge transfer transitions, has been observed for a long time in ZnO : Mn absorption spectra. In absorption spectra of a polarized light at 4.2 and 77.3 K, we first detected several lines of different intensity in a 1.877–1.936 eV range of energies of the light quanta. The observed lines are attributed to a donor exciton [( d ^5 + h ) e ] that emerges as a result of the Coulomb binding a free s electron and a hole, which is localized on p – d hybridized states. The EPR spectra of Mn^2+ ion signals, when corresponding to the impurity absorption band exposed to light, are found to be not photosensitive. The obtained results indicate that the ZnO : Mn impurity absorption is due to transitions from antibonding p – d hybridized DBH states to the conduction band.

scholarly journals On the influence of their state in solution on the absorption spectra of dissolved dyes

1909 ◽  
Vol 82 (554) ◽  
pp. 256-270 ◽  
Keyword(s):  
Refractive Index ◽  
Absorption Spectra ◽  
Organic Solvents ◽  
Absorption Maximum ◽  
Previous Investigation ◽  
Cyanine Dyes ◽  
Water Band ◽  
The One

In a previous investigation of the absorption spectra and sensitising properties of some iso cyanine dyes,* the influence of the solvent was examined and it was found that the absorption maximum was shifted toward the red as the refractive index of the solvent increased. This is in accordance with Kundt’s law. The absorption in water, however, differs markedly from that in organic solvents. In the latter the spectrum consists of a prominent band in the orange and a half-shade nearer the blue. In water this half-shade has become a separate band comparable in intensity with the orange. Absorption curves in alcohol and water are shown. It is convenient to term the band near the red the β-(organic) band, the one nearer the blue the α -(water) band. It appeared desirable to investigate this difference further.

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