Crystalline Plates Research Articles

Generalised theory of interference and its applications

The geometric method of specifying states of polarisation by points on the Poincare sphere is used for giving a unified and physically intelligible approach to the interference phenomena displayed by crystalline plates in parallel or convergent light-under general conditions when the polarising and analysing states are linear, circular or elliptic in form. Examples discussed are the spiral figures exhibited in convergent light (a) by the basal section quartz between a circular polariser and linear analyser (or vice-versa) and (b) by two superposed basal sections of left- and right- quartz between crossed nicols. The Airy's spirals observed in the latter case are interpreted as the 'isogyres' of the optically inactive plate to which the combination is equivalent.

X-ray diffraction and electron microscope studies on the brain lipide strandin

Electron micrographs of thin layers of strandin show a fairly regular rectangular arrangement of particles measuring approximately 60 × 100 × 100 A., the smallest dimension corresponding to the thickness of the layers. X-ray diagrams of thick crystalline plates show intense low-angle diffractions in three mutually perpendicular directions which correspond roughly to these dimensions. The diffraction spacings of different strandin preparations vary somewhat, and the effects of alcohol, and more particularly of water, suggest that strandin may be a complex or series of complexes in which some of the association of components is more physical than chemical.

IDENTIFICATION OF CRYSTALLINE INCLUSION BODIES EXTRACTED INTACT FROM PLANT CELLS INFECTED WITH TOBACCO MOSAIC VIRUS

THE INTRACELLULAR amorphous and crystalline inclusion bodies found particularly in the epidermal cells of plants infected with tobacco mosaic virus (TMV) have been the object of considerable investigation following the first description of them by Iwanowski (1903). There has been much speculation as to the nature and composition of both types of inclusions. The amorphous inclusions were called X-bodies by Goldstein (1924, 1926), who postulated that they were the infectious agent, and who also advanced the notion that the crystalline inclusions (striated bodies) were reaction products of the cell. The most critical observations of crystalline inclusion bodies have been made by Beale (1937), who described and illustrated the transformation of crystalline plates into needle crystals upon the addition of dilute acid or salt to the water in which epidermal strips had been mounted under the microscope. Beale considered these needle crystals to be identical with those obtained by Stanley, and concluded that the crystalline inclusions were the source of Stanley's purified TMV protein. The amorphous inclusions (X-bodies) found in cells of plants infected with aucuba mosaic virus have been isolated by Sheffield (1939), who was able to show that they contain active virus. She was unable to isolate any crystalline inclusions, however, and consequently could not make an unequivocal identification of their contents. Interest has recently been revived concerning the nature of the hexagonal crystalline inclusion bodies by the publication of a paper by Wilkins et al. (1950), who have investigated particularly, some of the optical properties of the crystals. They report that, in the great majority of the crystals, the previously observed (Bawden and Sheffield, 1939) striations are seen only between crossed Nicols and when the crystal is observed on edge with its near the extinction position. (The principal axis is a direction perpendicular to the hexagonal faces of the crystal.) They conclude that the crystals are built,up of thin, flat layers lying parallel to the hexagonal face of the crystal, and that within each layer the individual TMV rods are aligned parallel to each other, but with an orientation not quite parallel to that of the TMV rods in the adjacent layers. The axes of adjacent layers would consequently be non-parallel by a few degrees. This conclusion is largely based upon their reported observation that the light and dark bands (the striations) appear to interchange

Spectral Sensitivity of Photosensitive Acid Resists

Several resins, both synthetic and natural, used as acid resists in photoengraving, are rendered photosensitive by the addition of alkali dichromates. The mechanism of this photosensitization is not entirely clear, and the spectral sensitivity of the reaction for widely different resins may be of aid in a study of the reactions involved. In addition, such sensitometric data are useful in the practical application of the resists.Aluminum plates, coated with the resins, were exposed in a medium quartz spectrograph using a controlled white flame arc and rotating logarithmic spiral sector to produce wedge spectra. Calibration of the spectral energy incident on the plate was made from 2500A to the long wavelength sensitivity limit of the material at 5000A. Spectral sensitivities for the several resins are qualitatively similar when expressed in terms of incident energy. Coating thicknesses are of the order of 1 micron. At this thickness only a fraction of the incident energy is absorbed, as shown by transmission spectra through similar coatings on crystalline quartz plates.

Some Effects of Vibration on X-Ray Diffraction by Crystals

A technique is described which makes use of Bragg reflection of x-rays to give a “picture” of the vibration pattern on the face of a crystalline plate. The dependence of this pattern on the direction of the x-ray beam is illustrated, and a comparison between dust patterns and x-ray patterns for a vibrating bar fairly well establishes that the local curvature of the crystal is responsible for the observed increase in x-ray reflection. Reference is made to quantitative measurements on statically bent quartz and to an approximate theory treating the effect.

X-Ray Diffraction by Elastically Deformed Crystals

Published articles establish the fact that vibration or other inhomogeneous strain greatly increases the ability of a crystal to diffract x-rays. The present article gives experimentally determined relations between integrated intensity and strain for the rather simple case of static bending. All measurements were made on quartz plates, but a wide range of geometrical and crystalline parameters was covered nevertheless. In some cases, the integrated intensity for extreme bending was more than 20 times that from the unbent crystal. An approximate theory is developed which agrees well enough with the measurements to serve as a means of computing the effects of other types of strain or of other combinations of crystalline parameters. A qualitative study of vibrating crystalline plates is also described briefly.

Migration of Lithium and Several Multicharged Ions through Quartz Plates in an Electric Field. II

The kinetics of the migration of lithium ions through crystalline quartz plates has been studied. The migration is induced by an electric field and probably takes place through tunnels inherent in the crystal structure and parallel to the principal axis of the quartz. It was shown that the rate-determining step is not the migration with in the quartz plate, but is some step associated with the passage of the lithium ions into or out of the quartz plate. A previous investigation showed that the migration within the quartz plate is the rate-determining step for sodium ions. It was demonstrated that neither magnesium, zinc, cadmium, nor bismuth ions will migrate through quartz plates under our experimental conditions. Copper ions migrated through the quartz plates but caused the plate to crack in each experiment.

Migration of Sodium Ions through Quartz Plates in an Electric Field. I

The kinetics of the migration of sodium ions through crystalline quartz plates has been studied. This migration, which was induced by an electric field, is assumed to take place through tunnels inherent in the crystal structure and parallel to the principal axis of the quartz. It was shown that the only important mechanism of current flow is the migration of sodium ions through the quartz plate. The activation energy is from 22 to 25 kcal. and depends upon the potential gradient. The rate of migration of the sodium ions is essentially independent of the concentration of the sodium ions.

A High Resolving Power, Curved-Crystal Focusing Spectrometer for Short Wave-Length X-Rays and Gamma-Rays

Description is given of a transmission-type, curved-crystal focusing spectrometer for short wave-length x-rays, and gamma-rays having a dispersion of 1.186 x.u. per mm at short wave-lengths. The spectrometer utilizes the (310) planes of quartz in a crystalline plate of dimensions 80×70×1.0 mm curved cylindrically to a radius of two meters. High luminosity is obtained since the useful aperture in the crystal holder has an area of 10 cm2 and subtends 0.00025 stereradians at the focus. It also affords high resolution since by photographic tests with x-rays the curved plate has been shown to focus a specified x-ray wave-length to within 0.06 mm of the same position on the focal circle for all parts of its useful aperture and over the entire operating wave-length range. The geometry of the mechanism permits absolute measurements with a precision screw of the sine of the Bragg angle on both sides of the reflecting planes, affording a wave-length range which includes at longest wave-lengths the K-spectrum of silver and goes down to zero wave-lengths. For short wave-length gamma-rays the source is placed at the focus. A multiple-slit collimator of tapering die-cast lead partitions spaced apart with tapering separators, is used at short wave-lengths to transmit the monochromatic diffracted beam and absorb the directly transmitted and scattered heterogeneous beam. The present collimator limits the spectrum that can be studied to a shortest wave-length of 7. x.u. corresponding to 1.75 Mev. The intensity of the diffracted beam is to be measured with a special multi-cellular G. M. counting tube of high efficiency, provided with a number of thin lead partitions through which the beam passes successively. In photographic spectra made with this instrument the tungsten and also the silver Kβ1β3 doublet is completely and clearly resolved. Reproductions of such photographic x-ray spectra are shown in which the line breadths have substantially the natural breadth. Fluorescence spectra of silver have been made in 10-minute exposures. A companion paper gives the all-important precision technique of generating the curved cylindrical stainless steel clamping blocks for the crystal.

A New Calculus for the Treatment of Optical SystemsVI Experimental Determination of the Matrix*

A simple, straightforward method is described for determining experimentally the matrix of any, crystalline plate. The method involves three measurements of the state of polarization of light transmitted by the plate, and also a measurement of its transmission factor for natural light. These measurements determine the matrix uniquely, except for a phase factor whose practical significance is small. The conditions are stated for the application of the method to the more general type of optical system described in V. A statement of the content of future papers in this series is included.

A New Calculus for the Treatment of Optical SystemsV A More General Formulation, and Description of Another Calculus

After a brief review of the nature of the calculus, a formulation is provided for the application of the calculus to a wider class of optical systems than those postulated in the earlier papers of this series. The application is found, however, to be subject to the drastic limitation that the system must not depolarize the light passing through it. Since homogeneous crystalline plates are almost completely free of depolarization, this limitation does not exist in the previously contemplated application to piles of crystalline plates. A more powerful calculus, whose formulation is due to Soleillet and whose development is due to Perrin and Mueller, is described, and is found to be free of this limitation. Its general properties are compared with those of the calculus discussed in this series of papers.

Haidinger Interference Fringes in Plane-Parallel Crystalline Plates

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text Bruce H. Billings, "Haidinger Interference Fringes in Plane-Parallel Crystalline Plates," J. Opt. Soc. Am. 35, 570-573 (1945) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Scalar Polarization Fringes Produced by the Superposition of Crystalline Plates

Scalar Polarization Fringes Produced by the Superposition of Crystalline Plates

Pure Crystalline Rennin

NORTHROP1 has shown that crystallization is a useful procedure in the purification of certain enzymes. Crystalline form, however, is not reliable evidence of purity, as pointed out, for example, by Pirie2, but may be considered as confirmatory evidence. For these reasons, in a recent attempt in this laboratory to obtain pure rennin, conditions favouring crystallization have been chosen. A preparation consisting largely of flat crystalline plates but containing a small proportion of spheroids has been obtained. From the accompanying photomicrographs it can be seen that although the outline of the plates is irregular, it tends to be triangular or rectangular, that the bounding surfaces are plane, and that the small surfaces forming the 'edges' of the plates are at right angles to the main surfaces. The latter conclusion arises from the rectangular appearance of the plates when seen 'on edge'.

XC.On the measurement of the thickness of thin transparent crystalline plates

XC.<i>On the measurement of the thickness of thin transparent crystalline plates</i>

A Note on the Photographic Measurement of the Transmission of Fluorite in the Extreme Ultraviolet

The measurement of the transmission of a piece of colorless fluorite was made by photographic methods and the results are compared with those obtained with a photoelectric cell for the same crystalline plate. The wave-length range covered was between 1240 and 1600A.

DIFFUSION OF HELIUM THROUGH QUARTZ: RELATION TO TEMPERATURE

A qualitative study of the diffusion of certain gases through quartz has been made for ordinary temperatures and pressures.A nearly linear relation was found to exist between diffusion and pressure for constant temperature and a form of the equation satisfying the experimental results suggested. Temperature-diffusion curves were obtained and a comparison made to previous work. Permeability to helium of single quartz crystalline plates is independent of the direction in which the plate has been cut, but is only about one-half the value of that of fused quartz bulbs or plates.

Preliminary note on a new method of measuring directly the double-refraction in strained glass

In general the methods employed for observing the double-refraction in strained glass depend on the use of crossed Nicols, and are similar in principle to those used for observing the colours of crystalline plates. So far as the difference between the two indices of refraction is concerned, a method described by the author allows of continuous observation of the double-refraction throughout the spectrum.

Societies and Academies

Societies and Academies

On the relative retardation between the components of a stream of light produced by the passage of the stream through a crystalline plate cut in any direction with respect to the faces of the crystal

The relative retardation between the components of a stream of right produced by the passage through a crystalline plate can, as is well known, only be determined in finite terms in a limited number of special cases. In general it is necessary to be content with an approximate solution, and those hitherto published have, as far as I have ascertained, never been carried beyond terms of the second order with respect to the sine of the angle of incidence of the light, while they do not readily lend themselves to a further approximation. The following method of dealing with the problem, which, except for the labour of calculation, can easily be extended to terms of any order, may then be of practical use, and, as leading to in interesting relation between the corresponding terms in the development of the roots of a certain biquadratic equation, of some interest.