scholarly journals The structure of molecules in relation to their optical anisotropy.—Part I

1925 ◽  
Vol 107 (744) ◽  
pp. 684-693 ◽  
Keyword(s):  
Optical Anisotropy ◽  
Scattered Light ◽  
Incident Light ◽  
Incident Beam ◽  
Electric Vector ◽  
Scattering Of Light ◽  
Structure Of Molecules ◽  
Weak Component ◽  
Principal Directions

One of the most significant facts relating to the scattering of light in gases is the imperfection of polarisation of the light scattered in a direction perpendicular to the incident beam. The late Lord Rayleigh and Born explained this phenomenon as being due to the optical anisotropy of the molecule, that is, to the fact that the polarisation induced in a molecule depends on its orientation with respect to the electric vector in the incident light. Lord Rayleigh’s theory does not go into the question as to how the anistropy arises, but merely assumes that there are in each molecule three principal directions of vibration, along which the induced polarisations are different. If A, B, C are the moments induced in a molecule when its three principal directions are respectively along the direction of the electric vector in the incident light, then the ratio of the weak component to the strong in the transversely scattered light is given by r = 2 (A 2 + B 2 + C 2 ) - 2 (AB + BC + CA) / 4 (A 2 + B 2 + C 2 ) + AB + BC + CA. We now possess reliable measurements of the imperfection of polarisation in many gases and vapours, from the work of Lord Rayleigh and of Raman and Rao. Recently there has been carried out at Calcutta further measurement of the same quantity, in a series of organic vapours, by Mr. A. S. Ganesan. Some of these results are collected together in Table I.

scholarly journals On the theory of scattering of light

1938 ◽  
Vol 166 (926) ◽  
pp. 425-449 ◽  
Keyword(s):  
Scattered Light ◽  
Incident Light ◽  
Incident Beam ◽  
The State ◽  
Reciprocity Relation ◽  
Scattering Of Light ◽  
Plane Parallel ◽  
Solid Media ◽  
State Of Polarization ◽  
Light Components

In a series of recent investigations R. S. Krishnan (1934-8) demonstrated the existence of a new effect which will be called the Krishnan effect. It relates to the state of polarization of the light scattered by certain liquid or solid media in directions normal to the incident beam. To describe the effect let us denote with π the plane parallel to the direction of observation and to that of the incident beam. Since in the experiment this plane is usually horizontal we denote by H the intensity of those scattered light components which vibrate parallel to this plane, and by V those vibrating normal to π. In a similar manner subscripts h or v indicate whether the incident light vibrates parallel or normal to the plane. We distinguish therefore (see fig. 1) the four light components H h , H v , V h and V v . Following Krishnan the depolarizations are defined by P h = V h / H h , p v = H v / V v , p u = ( H h + H v )/( V h / V v ). p u is the depolarization for natural incident light. For most liquids the observations give, in agreement with the theories of temperature scattering, H h = V h = H v , hence p h = 1, p u = 2 p v /(1+ p v ). The Krishnan effect is the observation that in a number of liquid and solid systems p h = V h / H h ≠ 1, and V h = H v . Krishnan has called (2) the reciprocity relation. All observations have given p h < 1, but none of the present theories exclude the possibility that p h may assume values larger than 1.

The Depolarization of Light Scattered in Solutions of Rubber Like Polymers

1947 ◽  
Vol 20 (4) ◽  
pp. 912-915
Author(s):  
V. Tsvetkov ◽  
E. Frisman
Keyword(s):  
Optical Properties ◽  
Scattered Light ◽  
Incident Light ◽  
Incident Beam ◽  
The State ◽  
Dispersed Phase ◽  
Colloidal Solutions ◽  
State Of Polarization ◽  
Depolarization Of Light

Abstract Investigation of the depolarization of light, Δ, scattered by colloidal solutions is one of the methods of determining the dimensions, shape and optical properties of the particles suspended in them. A study of the state of polarization of the scattered light is found to be especially helpful in this respect. If the incident beam is directed along the x-axis of a rectangular system of coördinates and observation is carried out along the y-axis, the degree of depolarization of the scattered light is usually determined by the ratio Δ=Ix'Iz, where Ix and Iz are the x- and z-components, respectively, of the scattered light. Here one should discriminate between the quantity Δv (the electrical vector of the incident light parallel to the z-axis) and the quantity Δh (the electrical vector of the incident light parallel to the y-axis). On the basis of theories advanced by Rayleigh, Mie, and Gans one may draw the following general conclusions regarding the relation between Δ and the properties of the dispersed phase.

scholarly journals The structure of molecules in relation to their optical anisotropy.—Part II—Benzene and cyclohexane

1926 ◽  
Vol 110 (753) ◽  
pp. 123-133 ◽  
Keyword(s):  
Optical Anisotropy ◽  
Organic Molecules ◽  
Mutual Influence ◽  
Scattered Light ◽  
Incident Radiation ◽  
Fair Agreement ◽  
Electrical Field ◽  
Triatomic Molecules ◽  
Structure Of Molecules ◽  
Straight Line

In Part I the view was advanced that the optical anisotropy of the molecules of a gas which is evidenced by the depolarisation of the light scattered by it can to a large extent be attributed to the mutual influence of the doublets induced in the different atoms of the molecule by the electrical field of the incident radiation. Assuming that each atom is isotropic, and assuming the refractivity and anisotropy of the molecules of hydrogen, oxygen and nitrogen, the atomic refractivity and the distance apart between the “optical centres” was calculated in these cases. Extending the treatment to the case of triatomic molecules with the three atoms in a straight line, and using the previously obtained values for the atomic refractivities of nitrogen and oxygen and the diamond value of the atomic refractivity of carbon, the optical anistropies of the gases N 2 O, CO 2 and CS 2 were calculated. The corresponding values of the depolarisation of the transversely scattered light were found to be in fair agreement with experiment. In this paper the work is extended to the two organic molecules, benzene and cyclohexane.

SCATTERING OF LIGHT BY SMALL DROPS OF WATER

1943 ◽  
Vol 21a (12) ◽  
pp. 99-109 ◽  
Author(s):  
R. Ruedy
Keyword(s):  
Sharp Increase ◽  
Main Part ◽  
Scattered Light ◽  
Incident Light ◽  
Wave Length ◽  
Red Light ◽  
Great Strength ◽  
Scattering Of Light

When very small drops of water increase in size until their diameter is one-fourth of the wave-length of the incident light (2a/λ = 1/4), they scatter the light essentially according to Rayleigh's law for non-conducting particles. But when the diameter increases from λ/4 to λ/2, the intensity of light scattered along directions that point toward the source decreases almost to zero, the change being most marked between 2a/λ = 1/4 and 2a/λ = 3/8. The sharp increase in the proportion of scattered light with an increase in size, according to the sixth power of the radius, continues however in the directions along which the main part of the scattered light is radiated by the particle. As the scattering begins to deviate from that given by Rayleigh's law, colours other than blue appear with great strength; the dispersion of the colours increases with increasing size of the particles until mainly red light remains.

scholarly journals Stimulated Raman scattering in a non-eigenmode regime

2020 ◽  
Vol 8 ◽  
Author(s):  
Yao Zhao ◽  
Suming Weng ◽  
Zhengming Sheng ◽  
Jianqiang Zhu
Keyword(s):  
Raman Scattering ◽  
Stimulated Raman Scattering ◽  
Laser Energy ◽  
Scattered Light ◽  
Incident Light ◽  
Loss Mechanism ◽  
Constant Frequency ◽  
Electrostatic Wave ◽  
Particle In Cell ◽  
Stimulated Raman

Stimulated Raman scattering (SRS) in plasma in a non-eigenmode regime is studied theoretically and numerically. Different from normal SRS with the eigen electrostatic mode excited, the non-eigenmode SRS is developed at plasma density $n_{e}>0.25n_{c}$ when the laser amplitude is larger than a certain threshold. To satisfy the phase-matching conditions of frequency and wavenumber, the excited electrostatic mode has a constant frequency around half of the incident light frequency $\unicode[STIX]{x1D714}_{0}/2$ , which is no longer the eigenmode of electron plasma wave $\unicode[STIX]{x1D714}_{pe}$ . Both the scattered light and the electrostatic wave are trapped in plasma with their group velocities being zero. Super-hot electrons are produced by the non-eigen electrostatic wave. Our theoretical model is validated by particle-in-cell simulations. The SRS driven in this non-eigenmode regime is an important laser energy loss mechanism in the laser plasma interactions as long as the laser intensity is higher than $10^{15}~\text{W}/\text{cm}^{2}$ .

LIGHT SCATTERING TECHNIQUES FOR DISCRIMINATING BETWEEN OIL AND PARTICULATES IN CONTAMINATED WATER

1977 ◽  
Vol 1977 (1) ◽  
pp. 153-156 ◽  
Author(s):  
Bruce Friedman
Keyword(s):  
Particulate Matter ◽  
Light Scattering ◽  
Intensity Distribution ◽  
Scattered Light ◽  
Incident Light ◽  
Real Life ◽  
The State ◽  
Oil Droplets ◽  
State Of Polarization

ABSTRACT Light scattering techniques are used in several oil-in-water monitors, proposed or in existence. Particulate matter which may interfere with these monitors is also frequently found in oily wastes. An analysis is made of the potential of using measurements of the angular intensity distribution of scattered light in conjunction with determination of the state of polarization of the scattered light for discriminating between oil and particulates. The size conditions which apply to the oil droplets and particulates relative to the incident light allow the scattered light angular intensity distribution to be treated as a consequence of a combination of classical diffraction and of geometrical refraction and reflection. The state of polarization of the scattered light for oil droplets is investigated using expressions for the electric field which are approximations to the expressions of the Mie theory. For the particulate matter, the state of polarization is probed on the basis of light reflected from a plane. It is found that it would be difficult to discriminate between oil and particulates using measurements of the angular intensity distribution of scattered light even in conjunction with the determination of the state of polarization of the scattered light in a real life situation.

scholarly journals The light scattered by gases: its polarisation and intensity

1918 ◽  
Vol 95 (667) ◽  
pp. 155-176 ◽  
Keyword(s):  
Scattered Light ◽  
Incident Light ◽  
Direct Sunlight ◽  
Laboratory Methods

The present investigation is a development in various directions of that described in ‘Proc. Roy. Soc.,’ A, vol. 94, p. 453 (1918). It is there shown that the light scattered by air and other gases in the direction perpendicular to the beam is almost completely polarised. It is of importance to determine whether or not the polarisation of the scattered light at right angles to the beam is absolutely complete. Sky light is by no means completely polarised, but in that case the incident light is not all in one direction: for, besides direct sunlight, light from other parts of the sky and from the earth’s surface contributes to the scattering from any given element of volume. The question is whether, apart from these complications, the polarisation would be complete. This cannot be decided by observations on the sky, but the laboratory methods now described allow of its investigation, not only in air, but in other gases also.

Die Messung von Schallgeschwindigkeiten in optisch anisotropen Medien mit dem Schaefer–Bergmann-Verfahren

1971 ◽  
Vol 27 (4) ◽  
pp. 316-322 ◽  
Author(s):  
H. Küppers
Keyword(s):  
Incident Light ◽  
Incident Beam ◽  
Maximum Intensity ◽  
Bragg Angle ◽  
Optical Wave ◽  
Double Refraction ◽  
Principal Axes ◽  
Diffraction Of Light ◽  
Standing Ultrasonic Wave ◽  
Sound Velocities

If the optical wave front is not normal to one of the principal axes of the indicatrix, diffraction of light in crystals, caused by ultrasound, is observed with maximum intensity when the incident beam is off the Bragg angle by an amount depending on double refraction. In a crystal plate of finite dimensions a standing ultrasonic wave also generates waves with propagation directions which are inclined to the normal of the plate, and interfere with the measurement of sound velocities by the improved Schaefer–Bergmann method. These difficulties are overcome by an appropriate choice of the angle of the incident light beam. Experiments with triclinic and trigonal crystals are reported. Formulae are derived for calculating the angles of incidence necessary for any measurements of sound velocities in crystals.

A Hybrid Partial Coherence and Geometry Optics Model of Radiative Property on Coated Rough Surfaces

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Jun Qiu ◽  
Yuan Ting Wu ◽  
Zhifeng Huang ◽  
Pei-Feng Hsu ◽  
Lin-Hua Liu ◽  
...  
Keyword(s):  
Coating Thickness ◽  
Rough Surfaces ◽  
Scattered Light ◽  
Incident Light ◽  
Fdtd Method ◽  
Partial Coherence ◽  
Radiative Properties ◽  
Wave Number ◽  
Heating Process ◽  
Coherence Effect

Thermal and optical engineering applications of electromagnetic wave scattering from rough surfaces include temperature measurement, radiation heating process, etc. Most of the surfaces have random roughness and are often with coating material different from the substrate. However, the understanding of radiative properties of coated rough surfaces is not well addressed at this point. This paper presented a novel hybrid partial coherence and geometry optics (HPCGO) model to improve the generic geometry optics (GO) prediction by incorporating a previously developed partial coherence reflectance equation. In this way, HPCGO expands the applicable region of GO model and largely reduces the computation time of integrating different wavelength results in the regular hybrid model that considers coherence effect only. In this study, the HPCGO model is first compared with the more rigorous Maxwell equations solvers, the finite-difference time-domain (FDTD) method, and integral equation (IE) method. Then, the HPCGO model is applied to study the coherent effect of directional-hemispherical reflectance from coated rough surfaces. It is found the roughness of coated rough surface can cause partially coherent or noncoherent scattered light even if the incident light source is coherent. It also shows the reflected electromagnetic wave's coherence effect reduces with increased coating thickness and surface roughness, besides the previously recognized incident wave-number bandwidth. The effect of reduce coherence in scattered wave is quantified. Finally a regime map, even limited in the roughness and coating thickness dimensionless parameter ranges, provides the region of validity of the HPCGO model.

A Hybrid Partial Coherence and Geometry Optics Model of Thin Film Optics on Coated Rough Surfaces

2012 ◽  
Author(s):  
Yuan Ting Wu ◽  
Zhi-feng Huang ◽  
Pei-feng Hsu ◽  
Huaichun Zhou
Keyword(s):  
Rough Surfaces ◽  
Scattered Light ◽  
Incident Light ◽  
Fdtd Method ◽  
Computation Time ◽  
Partial Coherence ◽  
Wave Number ◽  
Heating Process ◽  
Coherent Effect ◽  
Coherence Effect

Thermal and optical engineering applications of electromagnetic wave reflectance from rough surfaces include temperature measurement, radiation heating process, etc. Most of the surfaces are random roughness and often with coating material different from the substrate. This paper presented a novel hybrid partial coherence and geometry optics (HPCGO) model to improve the generic geometry optics (GO) method by incorporating a previously developed partial coherence reflectance equation. In this way, HPCGO expands the applicable region of GO model, and largely reduces the computation time of integrating different wavelength results in the regular hybrid model that considers coherence effect only. First, the HPCGO model is validated by more rigorous Maxwell equations solvers, for example, the finite-difference time-domain (FDTD) method and integral equation (IE) method. Then, the HPCGO model is applied to study the coherent effect of directional-hemispherical reflectance from coated rough surfaces. It is found the roughness of coated rough surface can cause partial or non-coherent scattered light even if the incident light source is coherent. It also shows the coherence effect reduces with increased incident wave-number bandwidth.

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