scholarly journals Modelling the Rayleigh match

2004 ◽  
Vol 21 (3) ◽  
pp. 477-482 ◽  
Author(s):  
P.B.M. THOMAS ◽  
J.D. MOLLON
Keyword(s):  
Absorption Spectra ◽  
Optical Density ◽  
Field Size ◽  
General Behavior ◽  
Anticlockwise Rotation ◽  
Peak Sensitivity ◽  
The Individual ◽  
Unique Match

We use the photopigment template of Baylor et al. (1987) to define the set of Rayleigh matches that would be satisfied by a photopigment having a given wavelength of peak sensitivity (λmax) and a given optical density (OD). For an observer with two photopigments in the region of the Rayleigh primaries, the observer's unique match is defined by the intersection of the sets of matches that satisfy the individual pigments. The use of a template allows us to illustrate the general behavior of Rayleigh matches as the absorption spectra of the underlying spectra are altered. In a plot of the Y setting against the red–green ratio (R), both an increase in λmax and an increase in optical density lead to an anticlockwise rotation of the locus of the matches satisfied by a given pigment. Since both these factors affect the match, it is not possible to reverse the analysis and define uniquely the photopigments corresponding to a specific Rayleigh match. However, a way to constrain the set of candidate photopigments would be to determine the trajectory of the change of match as the effective optical density is altered (by, say, bleaching or field size).

Periodic variation in time of optical density in the electron absorption spectra of solutions of ferrocene and its derivatives

1981 ◽  
Vol 217 (2) ◽  
pp. 215-219 ◽  
Author(s):  
T.V. Burova ◽  
V.N. Trembovler ◽  
B.M. Yavorsky ◽  
N.V. Fock ◽  
R.B. Materikova ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Optical Density ◽  
Periodic Variation ◽  
Electron Absorption Spectra ◽  
Electron Absorption

scholarly journals III. A contribution to the study of the yellow colouring matter of the urine

1894 ◽  
Vol 55 (331-335) ◽  
pp. 394-407 ◽  
Keyword(s):  
Absorption Spectra ◽  
Spectroscopic Properties ◽  
Yellow Pigment ◽  
Chemical Methods ◽  
Distinctive Character ◽  
Yellow Coloration ◽  
Normal Urine ◽  
The Individual

The uncertainty which still surrounds the origin of a phenomenon so familiar as the yellow coloration of the urine bears eloquent testimony to the difficulties which beset the investigation, by ordinary chemical methods, of such substances as the urinary pigments, and to the importance of the part which the spectroscope has played in the acquisition of such knowledge of them as we possess. Indeed, our acquaintance with the individual pigments is proportional to the distinctive character of their absorption spectra, rather than to the time which has elapsed since they first attracted attention; and in not a few modern works doubt is thrown upon the very existence of a distinct yellow pigment, having negative spectroscopic properties, but to which normal urine owes its characteristic tint, the chief part in the coloration of the excretion being assigned to urobilin.

scholarly journals Permittivity spectra and structure of d-bands of germanium telluride, tin telluride and lead telluride

2020 ◽  
pp. 44-49
Author(s):  
D.A. Perevoshchikov ◽  
◽  
V.Val. Sobolev ◽  
A.I. Kalugin ◽  
E.A. Antonov ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Lead Telluride ◽  
Germanium Telluride ◽  
General Behavior ◽  
Electron Transitions ◽  
Tin Telluride ◽  
Experimental Absorption ◽  
Exciton Transitions

Based on the experimental absorption spectra, the permittivity spectra of GeTe, SnTe, and PbTe crystals were obtained in the region of electron transitions from core d -bands of cations. Their specific features and general behavior are revealed. The permittivity spectra of each crystal were decomposed into six elementary components and their main parameters were determined by using of combined Argand diagrams method. Based on the theory of interband and exciton transitions, the nature of the formation of these oscillators was proposed.

Heparin and sulfated mucopolysaccharides—a micro system for quantitative differentiation and determination

1977 ◽  
Vol 55 (5) ◽  
pp. 1179-1189 ◽  
Author(s):  
Louis B. Jaques ◽  
Tak K. Sue ◽  
Norman M. McDuffie ◽  
Sandra M. Wice
Keyword(s):  
Aqueous Solution ◽  
Hyaluronic Acid ◽  
Optical Density ◽  
Toluidine Blue ◽  
Linear Relation ◽  
Cetylpyridinium Chloride ◽  
Agarose Gel ◽  
Azure A ◽  
Tissue Extracts ◽  
The Individual

Heparin (Hep), hyaluronic acid, chondroitins (sulfate) A, B, and C, and heparitins (sulfate) A, B, C, and D were subjected to microelectrophoresis in barbital–agarose gel, fixed with cetylpyridinium chloride and stained with toluidine blue. The optical densities of the resulting bands were compared with optical densities obtained upon reaction with azure A in aqueous solution and with the carbazole reagent. A linear relation was obtained between optical density and concentration of purified sulfated mucopolysaccharide (SMP). Less than 1 μg of Hep and 2 μg of other SMPs are required for measurement by electrophoresis, while about 30 μg of each is required with the carbazole reagent. The optical density of a mixture of SMPs was equal to the sum of the densities for the individual SMPs upon microelectrophoresis. It was demonstrated that the individual SMPs in mixtures were distinguished by reaction with specific enzymes and by changes in migration in agarose with barbital, phthalate, ethylenediamine, or propane-diamine buffers, permitting ready demonstration and quantitation of various SMP species. Examples are shown of the application of the procedure to measure the total SMPs and individual SMPs in tissue extracts. The method is sensitive, reproducible, flexible, and measures quantities [Formula: see text] of those measured colorimetrically, yet is relatively unaffected by protein, carbohydrate, or inorganic electrolytes.

Spectra of the 1:1 and 3:1 solid complexes of coronene-TCNQ

1977 ◽  
Vol 55 (21) ◽  
pp. 3712-3716 ◽  
Author(s):  
Kim Doan Truong ◽  
André D. Bandrauk
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Ground State ◽  
Electronic Absorption Spectra ◽  
Charge Transfer Band ◽  
Out Of Plane ◽  
The Individual ◽  
A Charge ◽  
Solid Complexes

Two new solid TCNQ complexes have been isolated, coronene–TCNQ 1:1 and 3:1. The infrared and electronic absorption spectra are presented for the two different stoichiometries. From these spectra we infer that the complexes are covalent in the ground state with a charge transfer band appearing at 730 nm. The out of plane vibrations of the individual molecules are noticeably perturbed upon complexation.

Spectrophotometric study of the effect of tensides on triphenylmethane dyes

1982 ◽  
Vol 47 (3) ◽  
pp. 776-784 ◽  
Author(s):  
Vlasta Škarydová ◽  
Ludmila Čermáková
Keyword(s):  
Absorption Spectra ◽  
Spectrophotometric Study ◽  
Triphenylmethane Dyes ◽  
Experimental Conditions ◽  
Bromopyrogallol Red ◽  
Strong Electrolytes ◽  
The Individual ◽  
Triton X

The effect of cation-active tenside 1-carbethoxypentadecyltrimethylammonium bromide (Septonex) on the absorption spectra of selected triphenylmethane dyes, eriochromcyanine R and bromopyrogallol red, was studied. The effect of the micelle aggregates of the tenside on the spectrophotometric characteristics of the individual dissociated forms of the dyes was demonstrated and the influence of strong electrolytes (NaCl, NaNO3) was studied. The interaction of both dyes with the micelle form of the nonionic tenside Triton X-100 was studied under similar experimental conditions.

Optical absorption spectra of octahedrally bonded Fe3+ in vesuvianite

1968 ◽  
Vol 5 (1) ◽  
pp. 89-92 ◽  
Author(s):  
P. G. Manning
Keyword(s):  
Optical Absorption ◽  
Energy Range ◽  
Absorption Spectra ◽  
Excited States ◽  
Ground State ◽  
Electronic Transitions ◽  
Optical Absorption Spectra ◽  
Sharp Band ◽  
Individual Bands ◽  
The Individual

The optical absorption spectra of green vesuvianite crystals from Lowell County, Vermont, are reported in the energy range 12 000 cm−1 to 30 000 cm−1. The principal absorptions have been attributed to octahedrally bonded Fe3+ and the individual bands have been assigned to spin-forbidden electronic transitions from the 6A1 ground state to excited states in Fe3+. In particular, the 6A1 → 4A14E(G) transition is marked by a relatively sharp band at 21 600 cm−1.

THE INFRARED ABSORPTION SPECTRA OF DEUTERATED ESTERS: II. ETHYL ACETATE

1956 ◽  
Vol 34 (10) ◽  
pp. 1392-1404 ◽  
Author(s):  
B. Nolin ◽  
R. Norman Jones
Keyword(s):  
Absorption Spectrum ◽  
Ethyl Acetate ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Infrared Absorption Spectrum ◽  
Absorption Characteristic ◽  
Stretching Vibration ◽  
Methylene Groups ◽  
Infrared Absorption Spectra ◽  
The Individual

The infrared absorption spectrum of ethyl acetate has been compared with the spectra of seven derivatives deuterated in the methyl and methylene groups. In the region 3500–1300 cm.−1 most of the bands can be assigned to vibrations localized in the individual groups. Absorption characteristic of the trideuteromethyl and dideuteromethylene groups can be recognized between 2300 and 2000 cm.−1. The C=O stretching vibration shows progressive displacement to lower frequency with increasing deuteration. The spectra in the range 1300–700 cm.−1 are also reported.

A Spiral Model of Rubber

1930 ◽  
Vol 3 (2) ◽  
pp. 201-206 ◽  
Author(s):  
H. Fikentscher ◽  
H. Mark
Keyword(s):  
Carbon Atom ◽  
Organic Compounds ◽  
Chemical Properties ◽  
Parent Substance ◽  
Chain Model ◽  
X Ray ◽  
General Behavior ◽  
The Individual ◽  
Spiral Model ◽  
Primary Valence

Abstract As a result of the work of Harries, the synthesis of rubber-like substances and the recent X-ray researches of Katz and of Hauser and his collaborators, one is justified in regarding the isoprene residue as the basis of the structure of rubber. The reason it has not been possible to obtain quite 100 per cent. of isoprene from rubber, in the way that cellulose can be converted quantitatively into its parent substance, glucose, is because of the strength of the C-C bonds of the individual isoprene residues of the rubber compared with the more easily cleaved glucoside oxygen bridges in cellulose. Above all, the extraordinarily thorough investigations of Staudinger and his collaborators have contributed important facts about the general behavior of chain-forming molecules, the application of which to rubber leads to the conviction that rubber contains long chains held together by primary valences, called macromolecules by Staudinger, a view which was held by Pickles years ago (cf. Ditmar, Der Kautschuk, 1912). Utilizing the Bragg numbers for the diameter of the carbon atom in organic compounds, Meyer and Mark have proposed a “primary valence chain model” of rubber, which conforms to the X-ray data and to the most important chemical properties. Since its general features have been pretty well confirmed, it seems a suitable time to improve this model, to develop it further structurally and to attempt to make clear the mechanical and other properties of the substance.

scholarly journals Изучение спектров поглощения вин различных типов и возраста в УФ-диапазоне длин волн

2019 ◽  
pp. 158-161
Author(s):  
Ruslan Timofeev ◽  
Nina Fomenko ◽  
Aleksandr Panasyuk
Keyword(s):  
Absorption Coefficient ◽  
Absorption Spectra ◽  
Wavelength Range ◽  
Optical Density ◽  
Mass Concentration ◽  
Methodological Approach ◽  
Total Phenolic ◽  
Spectra Analysis ◽  
Phenolic Substances

Приведены результаты анализа спектров поглощения вин различных типов и возраста в УФ-диапазоне длин волн. Определены закономерности изменения оптической плотности в УФ-диапазоне длин волн образцов вин в зависимости от их типа и возраста. Показано, что оптическая плотность вин одного возраста на длине волны 280 nm пропорциональна массовой концентрации суммы фенольных веществ, определенной с реактивом Фолина-Чокальтеу. Введено понятие «коэффициента поглощения фенольных веществ винограда и вина». Разработан методологический подход к определению массовой концентрации фенольных веществ в молодых винах.The paper highlights the results of the absorption spectra analysis of base wines of various types and ages in the UV wavelength range. Patterns have been established for optical density vatriations in the UV wavelength range of base wine samples depending on their type and age. It is shown that the optical density of base wines of the same age at the wavelength of 280 nm is proportional to the mass concentration of total phenolic substances, determined with Folin-Chocalteu reagent. The concept of “phenolic substances of grapes and wine absorption coefficient” was introduced. A methodological approach was developed to determine mass concentration of phenolic substances in young base wines.

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