scholarly journals THE VISIBILITY OF MONOCHROMATIC RADIATION AND THE ABSORPTION SPECTRUM OF VISUAL PURPLE

1922 ◽  
Vol 5 (1) ◽  
pp. 1-33 ◽  
Author(s):  
Selig Hecht ◽  
Robert E. Williams
Keyword(s):  
Refractive Index ◽  
Absorption Spectrum ◽  
Absorption Coefficient ◽  
Experimental Verification ◽  
High Intensity ◽  
Absorption Maximum ◽  
Water Solution ◽  
Wave Length ◽  
Relative Energy ◽  
Existing Data

1. After a consideration of the existing data and of the sources of error involved, an arrangement of apparatus, free from these errors, is described for measuring the relative energy necessary in different portions of the spectrum in order to produce a colorless sensation in the eye. 2. Following certain reasoning, it is shown that the reciprocal of this relative energy at any wave-length is proportional to the absorption coefficient of a sensitive substance in the eye. The absorption spectrum of this substance is then mapped out. 3. The curve representing the visibility of the spectrum at very low intensities has exactly the same shape as that for the visibility at high intensities involving color vision. The only difference between them is their position in the spectrum, that at high intensities being 48 µµ farther toward the red. 4. The possibility is considered that the sensitive substances responsible for the two visibility curves are identical, and reasons are developed for the failure to demonstrate optically the presence of a colored substance in the cones. The shift of the high intensity visibility curve toward the red is explained in terms of Kundt's rule for the progressive shift of the absorption maximum of a substance in solvents of increasing refractive index and density. 5. Assuming Kundt's rule, it is deduced that the absorption spectrum of visual purple as measured directly in water solution should not coincide with its position in the rods, because of the greater density and refractive index of the rods. It is then shown that, measured by the position of the visibility curve at low intensities, this shift toward the red actually occurs, and is about 7 or 8 µµ in extent. Examination of the older data consistently confirms this difference of position between the curves representing visibility at low intensities and those representing the absorption spectrum of visual purple in water solution. 6. It is therefore held as a possible hypothesis, capable of direct, experimental verification, that the same substance—visual purple—whose absorption maximum in water solution is at 503 µµ, is dissolved in the rods where its absorption maximum is at 511 µµ, and in the cones where its maximum is at 554 µµ (or at 540 µµ, if macular absorption is taken into account, as indeed it must be).

Study the Nonlinearity Characteristics of Organic-Semiconductor (CuPc) Prepared Via Pulsed Laser Deposition Technique with Different Thickness

2019 ◽  
Vol 27 ◽  
pp. 11-20 ◽  
Author(s):  
Mohammed T. Hussein ◽  
Reem R. Mohammed
Keyword(s):  
Refractive Index ◽  
Absorption Spectrum ◽  
Pulsed Laser Deposition ◽  
Copper Phthalocyanine ◽  
Wave Length ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Deposition Technique ◽  
Linear Refractive Index ◽  
Non Linear

The optical absorption spectrum, Photoluminesces, and non-linear optical properties for Copper Phthalocyanine (CuPc) thin films (150,300 and 450 nm) respectively have been investigated via pulsed laser deposition technique. The absorption spectrum indicted that there are two bands one in UV around 330 nm which called B-band and the second in Visible around 650nm which called Q-band. Photoluminescence spectrum related to deposit samples has been determined with different thicknesses. From closed and open aperture Z-scan data non-linear absorption coefficient and non-linear refractive index have been calculated respectively using He-Ne laser which have beam waist of (24.2 μm), wave-length of (632.8 nm) and Rayleigh thickness was 2.9 mm. Through dividing closed by open apertures, non-linear refractive index was calculated accurately. Finally, the study also showed the suitability of the deposited films as an optical limiter at the wavelength 632.8 nm.

scholarly journals On the transmission of light by thin films of metal

1931 ◽  
Vol 131 (817) ◽  
pp. 307-320 ◽  
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Absorption Coefficient ◽  
Transmission Coefficient ◽  
Common Knowledge ◽  
Wave Length ◽  
Gold Wire ◽  
Spherical Particles ◽  
Gold Films ◽  
Gold Leaf

It is a matter of common knowledge that an ordinary gold leaf apperars green by transmitted light while silver leaf appears blue. Faraday found that the gold leaf lost all its colour if heated on glass. T. Turner found that this change occurs at about 550° C. in the case of gold and about 240° C. in the case of silver. Faraday obtained thinner films from the "deflagration" of gold wire by the discharge of a Leyden jar battery. These were red and violet in places and green in others. They turned red on heating, but the green colour could be brought back by rubbing with a rounded piece of agate. The gold films used by Beilby, obtained from paints used for ceramic gilding, behaved in a similar manner. One of his thin purple films turned rose-pink on annealing, and his thicker green films became transparent at a temperature above 400°C. R. W. Wood obtained purple, blue and green films of gold by sputtering. He found that films of all other colours could be turned green by heating, as opposed to Faraday and Beilby. Maxwell Garnett has explained the colours observed by Beilby, Faraday and R. W. Wood by considering the films as made up of minute spherical particles of metal. He finds that the transmission-coefficient T, of films for which πd/λ is very small, is given by T = 1 - 4π dn 2 k /λ, where d is the thickness of the film, k the absorption coefficient, n the refractive index, and λ the wave-length of the light used.

SOLVENT EFFECTS IN THE DETERMINATION OF THE NONLINEAR OPTICAL PROPERTIES

2008 ◽  
Vol 17 (04) ◽  
pp. 511-520 ◽  
Author(s):  
A. MENDOZA-GARCÍA ◽  
J. L. PAZ ◽  
M. GORAYEB ◽  
A. J. HERNÁNDEZ ◽  
E. CASTRO ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Probability Distribution ◽  
Absorption Coefficient ◽  
Solvent Effects ◽  
High Intensity ◽  
Signal Intensity ◽  
Nonlinear Optical ◽  
Molecular System

The interaction between a two-level molecular system and a high intensity electric field under the influence of a solvent was analyzed through the OSBE. To solve these equations, the average of the coherence was performed, using a generalized Lorentzian approximation for the Voigt's function as a probability distribution. Applying the convolution theorem, we were able to find an analytical expression for the coherence, from which we calculate optical properties, such as the absorption coefficient, refractive index and emitted signal intensity. In this contribution, we show numerical results for these properties, calculated for a standard model of organic colorants, Green Malaquite.

Linear and Nonlinear Optical Properties of Natural Dyes Freestanding Films and Application in Optical Limiting

2020 ◽  
pp. 139-143
Keyword(s):  
Absorption Coefficient ◽  
Water Solution ◽  
Optical Limiting ◽  
Refraction Index ◽  
Laser Wavelength ◽  
Solid State Laser ◽  
Natural Dyes ◽  
Linear And Nonlinear ◽  
532 Nm ◽  
Absorbance Spectra

Natural dyes were followed and prepared from a pomegranate, purple carrot, and eggplant peel. The absorbance spectra was measured in the wavelength range 300-800 nm. The linear properties measurements of the prepared natural dye freestanding films were determined include absorption coefficient (α0), extinction coefficient (κ), and linear refraction index (n). The nonlinear refractive index n2 and nonlinear absorption coefficient β2 of the natural dyes in the water solution were measured by the optical z-scan technique under a pumped solid state laser at a laser wavelength of 532 nm. The results indicated that the pomegranate dye can be promising candidates for optical limiting applications with significantly low optical limiting of 3.5 mW.

Effective Dielectric Function of Porous Silicon: the Transverse Component

1994 ◽  
Vol 358 ◽  
Author(s):  
G. Gumbs
Keyword(s):  
Absorption Spectrum ◽  
Absorption Coefficient ◽  
Electron Density ◽  
Quantum Wires ◽  
Interband Transition ◽  
Incident Light ◽  
Transverse Component ◽  
Effect Of Temperature ◽  
High Electron ◽  
Confining Potential

ABSTRACTA self-consistent many-body theory is developed to study the effect of temperature and electron density on the interband absorption coefficient and the frequency-dependent refractive index for an array of isolated quantum wires. The peaks in the absorption coefficient correspond to interband transitions resulting in the resonant absorption of light. The oscillations in the derivative spectrum are due to the quantization of the energy levels related to the in-plane confining potential for such reduced dimensional systems. There are appreciable changes in the absorption spectrum when the electron density or temperature is increased. One interband transition peak is suppressed in the high electron density limit and the thermal depopulation effect on the electron subbands can be easily seen when the temperature is high. We also find that the exciton coupling weakens the shoulder features in the absorption spectrum. This study is relevant to optical characterization of the confining potential and the areal density of electrons using photoreflectance. By using incident light with tunable frequencies in the interband excitation regime, contactless photoreflectance measurements may be carried out and the data compared with our calculations. By fitting the numerical results to the peak positions of the photoreflectance spectrum, the number of electrons in each wire may be extracted.

scholarly journals On the absorption of light by crystals

1938 ◽  
Vol 167 (930) ◽  
pp. 384-391 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Wave Length ◽  
Short Wave ◽  
Point Of View ◽  
Theoretical Point ◽  
Lattice Vibrations ◽  
Short Wave Length ◽  
Continuous Absorption ◽  
Absorption Of Light ◽  
Positive Hole

The purpose of this paper is to discuss the absorption of light by non-metallic solids, and in particular the mechanism by which the energy of the light absorbed is converted into heat. If one considers from the theoretical point of view the absorption spectrum of an insulation crystal, one finds that it consists of a series of sharp lines leading up to a series limit, to the short wave-length side of which true continuous absorption sets in (Peierls 1932; Mott 1938). In practice the lattice vibrations will broaden the lines to a greater of less extent. When a quantum of radiation is absorbed in the region of true continuous absorption, a free electron in the conduction band and a "positive hole" are formed with enough energy to move away from one another and to take part in a photocurrent within the crystal. When, however, a quantum is absorbed in one of the absorption lines , the positive hole and electron formed do not have enough energy to separate, but move in one another's field in a quantized state. An electron in a crystal moving in the field of a positive hole has been termed by Frenkel (1936) an "exciton".

Potential barrier effect and discrete structure o between 40 and 120 Å in the Rb I absorption spectrum

1975 ◽  
Vol 344 (1637) ◽  
pp. 303-309 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Absorption Maximum ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Particle Model ◽  
Discrete Structure ◽  
Model Calculations ◽  
Hartree Fock ◽  
Independent Particle ◽  
Independent Particle Model

Investigation of the Rb I absorption spectrum between 40 and 120 Å has revealed a broad absorption maximum in the 3d photoionization continuum, as well as discrete features associated with the excitation of a 3d-subshell electron. The discrete structure is identified, Hartree-Fock calculations of the transition energies are given and the absorption maximum is discussed in relation to similar spectra and to recent random phase approximation with exchange (r.p.a.e.) and independent particle model calculations.

Study the Effect of Heat Treatment and Pressure on some the Optical Properties of the Pure PVA Nano Polymer

2021 ◽  
Vol 900 ◽  
pp. 16-25
Author(s):  
Tabarak Mohammed Awad ◽  
May A.S. Mohammed
Keyword(s):  
Heat Treatment ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Polyvinyl Alcohol ◽  
Complex Dielectric Constant ◽  
Different Temperatures ◽  
German Origin ◽  
Increasing Temperature

In this study, some optical properties were studied of the pure vinyl polyvinyl alcohol (PVA) nanopolymer (German origin). Under the influence of different temperatures and pressures of PVA. Where 25 samples were prepared for the purpose of conducting the research. Which studied the study of these samples was done by recording the absorbance and transmittance spectra of the wavelengths (200-900) nm. From them, absorbance, transmittance, reflectivity, absorption coefficient, refractive index, extinction coefficient, complex dielectric constant were calculated. At different temperatures (25,40, 80, 120, 160)°C. And with different pressures within the range (7.5,8,8.5,9,9.5) MPa. The results are that the permeability of the polymer (PVA) at different temperatures for each pressure decreases with increasing temperature, and that all other calculated optical properties increase with increasing temperature.

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