Direct Vision Spectroscope Research Articles

An electronic spectroscope for classroom displays of visible spectra

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), a section of Spectrochimica Acta Part B (SAB). The hardcopy text is accompanied by an electronic archive, stored on the SAE homepage at http://www.elsevier.nl/locate/sabe. The archive contains program, data and text files. The hardcopy text describes a program that has been developed to accept data from a compact electronic spectrograph and translate the data into a display on a computer screen. The computer display mimics the view seen through a direct vision spectroscope. Atomic spectra appear as vertical lines of the appropriate color dispersed on a black field. A conventional plot of intensity versus wavelength is simultaneously displayed. The update of the display is sufficiently rapid that the image on the screen is essentially a real-time representation of the light entering the spectrograph. The system was designed for use in conjunction with video projection equipment in demonstrations to large groups of students.

Raman effect: History of the discovery

AbstractThe paper gives a historical account of the discovery of the Raman Effect, starting from Raman's voyage to Europe through the Mediterranean Sea in the summer of 1921 to the observation of modified lines in benzene when illuminated by the 435.8 nm radiations of mercury, through a direct vision spectroscope, on 28 February 1928. The important contributions of Raman and his students during the period which form the progressive stages in the road to discovery have been briefly touched upon. The work of the French group, the Russian group and the theoretical work of Smekal are narrated in sequence.

Cytochromes of Fungi

SUMMARY The mycelia of 45 species of fungi were examined using a direct-vision spectroscope and in every instance absorption bands of cytochromes were seen. The relative positions of the bands varied, but this variation was not considered sufficient to suggest the presence of cytochromes additional to those normally found in yeast. Since Keilin's original paper entitled 'On cytochrome, a respiratory pigment common to animals, yeast and higher plants' (Keilin, 1925), there have been few observations on the occurrence of cytochromes in fungi. Cytochromes have been recorded in Neurospora crassa and Penicillium, notatum (Keilin and Tissieres, 1953); certain strains of N. crassa show variations from the normal cytochrome system of the wild type (Tissieres and Mitchell, 1954). Neilands (1952) isolated cytochrome c from Ustilago sp. whilst cytochrome oxidase has been shown to occur in Myrothecium verrucaria (Darby and Goddard, 1950), in Aspergillus spp. (Tamiya, 1942), and in Blastocladiella emersonii (Cantino and Horenstein, 1955). In the latter organism the enzyme was apparently not present in the thick-walled resistant sporangia. This paper records the results of direct spectroscopic examinations for the presence of cytochromes within the mycelium of a series of fungi. MATERIAL AND METHODS

Graphical Solutions to Optical Problems of Three Different Types

The following problems are considered: I. Paraxial ray tracing by the focal plane method.—For spherical refracting and reflecting surfaces it is shown that by drawing two secondary axes, one parallel to a ray incident at an arbitrary angle and the other parallel to the path of the same ray after refraction or reflection, the positions of the focal planes are readily established and their necessary properties deduced. The same is done for a lens by a method based on the fact that a focal plane of the first surface is conjugate to a focal plane of the second surface. II. The variation in the distance L between the conjugate foci of a thin lens (focal length f) with the distance l of one focus from the lens.—A general formula is established, and a simple construction for plotting the graphs between L/f and l/f is described. III. Refraction by prism combinations and the prism refractometer.—A graphical method is used to discuss the design of the Amici prism, the direct vision spectroscope, and achromatic prisms giving appreciable deviations. A graphical method is also described for finding the refractive index of a liquid from results obtained with a prism refractometer.

Band spectra of cathodo-luminescence

Much has been published on the emission spectra of solid fluorescent materials when excited by various kinds of radiation, especially ultraviolet light. The study of the comparatively few cases of line emission, for example, by Tomaschek and by Deutschbein, has given precise results in contrast to the very variable data available for band spectra. The methods adopted in earlier work for determining the position of emission bands have frequently been inexact or liable to subjective errors. Lenard and his school (1928) used the spectrophotometer or even a direct vision spectroscope. Rothschild (1937) used photographic methods resembling those of absorption spectrophotometry, but in general the spectrophotometer has been employed most; it is unsuitable for the examination of cathodo- fluorescence on account of the difficulty of maintaining constant excitation during a long series of observations. In the present work, which is largely concerned with cathodo-fluorescence at room temperature, the spectra were photographed, the densities recorded by a microphotometer, and from the resulting curves the intensities in the original emission bands calculated. By a similar method Schellenberg (1932), working on ultraviolet excitation, and Kutzner (1937) on α -particle scintillations, obtained complex band systems which were analysed algebraically into hypothetical components. This was unnecessary for nearly all the materials considered below, which gave either single bands or complexes adequately separated by graphical methods.

An apparatus for viewing varying thicknesses of a solution with a direct-vision spectroscope

An apparatus for viewing varying thicknesses of a solution with a direct-vision spectroscope

A Case of Dispersion Without Deviation of the Mean Ray

This paper shows that a direct vision spectroscope may use a glass prism immersed in a liquid contained in a cell with parallel ends. The effect of changing the prism angle is shown, and the data for a 14° dispersion are given.

THE HICKS SPECTRA-DEMONSTRATOR AND COLOR ABSORPTION DEMONSTRATOR

The Hicks spectra-demonstrator consists of a number of light sources mounted on a rotating table, and a small direct vision spectroscope for forming and viewing their spectra. Any one of the sources may be placed directly behind the spectroscope by turning the handle in front of the case, which rotates the table. There are nine sources : two spark sources with iron and copper terminals; four vacuum tubes containing helium, neon, dry air, and mercury vapor; and three incandescent bulbs, giving continuous spectra, of which one is seen directly, one through red glass which absorbs all the colors except red, and the third through didymium glass which absorbs several narrow bands. The spectroscope is a combination of a celluloid replica grating, which forms the spectrum, and a prism that bends the central ray back to its original direction. Spectrum analysis is based on the fact that all substances in the form of vapor or gas give characteristic spectra. A spectrum is a band of light in which each color has its definite place : blue at one end, then green, yellow, orange, and red at the other end. An incandescent solid, such as the filament of an electric light, gives light of all colors so that its spectrum is continuous. If a gas or vapor is excited to incandescence by passing an electric current through it, it will give out light of certain definite colors and the spectrum will consist of a few bright lines instead of being continuous. The spectrum of hydrogen, for example, has a bright line in the red, one in the blue-green, another in the violet, and others extending beyond the limit of vision. No other substance gives the same set of lines as hydrogen; hence that particular pattern always indicates hydrogen. If two or more elements form a chemical compound, or two or more atoms of a single element are united, the spectrum consists of a great many lines crowded together into what is called a band. The first lines are very strong, the others are successively fainter. A pattern of bands is as distinctive of a compound as is the single-line

New Evidence of the Action of Sunlight on Aurora Rays

ON Mar. 15 last I received information from the State Telegraphic Department that earth currents were disturbing the telegraphic service. Believing that we should have an aurora in the evening, I warned my four photographic stations, Oslo, Kongsberg, Tomte, and Oscarsborg, to be ready for action immediately after sunset. Using the excellent type of direct vision spectroscope described by Lord Rayleigh,1 I was able to localise an aurora arc in the northern sky during the twilight, long before it was possible to distinguish it visually.

The spectrum of carbon arcs in air at high current densities

Although the spectrum of the ordinary carbon arc has been studied in great detail during the last 70 years, there seems to have been no similar study of the “High Current Density” arc which was introduced by Beck in 1914. Spectrophotometrical measurements have been made in connection with the development of this type of arc for searchlights, and photographs of the spectra obtained from the total radiation from the arc have been published. The only account, however, of the spectrum from individual parts of the arc appears in a short note by Bell and Bassett. They examined an image of the arc on a ground glass screen with a direct vision spectroscope and reported that in the arc stream 15 lines appeared when the current exceeded 100 amperes. They attributed 7 of these to helium and 2 to hydrogen.

White-Light Interference Fringes with a Thick Glass Plate in One Path

In Part I of this paper [1] the writer developed a theory of the white-light fringes observed in the Michelson interferometer when a thick plate of glass, or other refractive substance, is placed in one of the paths. Part I treated of the axial beam, whose composition determines the color of the central spot in the fringe pattern. An explanation was given of the very great number of colored fringes, running up to several thousand, which is observed under these conditions. In this part we discuss certain phenomena which depend for their explanation upon the analysis of a beam oblique to the optical axis. To observe these phenomena we obtain, as described in Part I, circular fringes in sodium light, insert the thick plate in one of the paths, shorten that path until in the neighborhood of the most brilliant sodium maximum, in which position colored fringes will be seen with white light. If we observe these fringes through a spectroscope with the slit placed across the center of the system, the slit being long enough to cut across the whole field, the spectrum is seen to be crossed by a system of concentric dark rings, looking very much like a shadow of the fringe system itself. If now one of the paths is slowly shortened or lengthened, these dark rings expand or contract, as the case may be, just as in the fringe system. In addition, the center of the system on the spectrum travels very slowly from one end of the spectrum to the other. These phenomena may be observed easily and distinctly if a rather wide slit, cut in a card, is placed in the path of the light before it enters the interferometer, and the fringes are then viewed through a direct-vision spectroscope, without slit.

The spectrum of radium emanation

In May, 1904, one of the authors, in conjunction with Professor Collie measured the visual spectrum of the emanation accumulated in 14 days from 109 milligrammes of radium bromide, by means of a direct vision spectroscope. A subsequent measurement was made with 11 days’ accumulation. It was then stated* :—“ The spectrum was very brilliant, consisting of very bright lines, the spaces between them being perfectly dark ; it had a striking resemblance in general character to the spectra of the gases of the argon group.” This spectrum became rapidly faint, and had largely disappeared in less than a minute; it was replaced by the spectrum of secondary hydrogen.

NOTE ON SOME METEOROLOGICAL USES OF THE POLARISCOPE

This is merely a preliminary notice of certain facts regarding atmos pheric polarization which may prove to have some prognostic value. They were incidental to a proposed study of the character of autumnal haze which the writer undertook last year at Mount Moosilauke, N. H. This peak, 4811 feet high, has an almost uninterrupted sweep of horizon over a radius of one hundred miles or so and offers an excellent chance for investigating the distribution and nature of the haze that veils the landscape in early autumn. For instruments I took along a Savart polariscope, merely a Savart plate with a bit of tourmaline as analyzer, an extemporized double-image polarimeter of the type outlined in the early and valuable paper of Professor E. C. Pickering,1 a couple of carefully calibrated photographic wedges for determining opacities, and a direct vision spectroscope. A prolonged easterly storm, about the only thing which could have defeated the program, cut short observations upon the summit, but a week of preliminary observations at Breezy Point (elevation 1650 feet) at the base of the mountain yielded results which seem to be of suffi cient interest to put upon record. These were made mostly with the Savart polariscope, an instrument which, from its very wide field of view and great sensitiveness, showing even one or two per cent of polarization, enables sky conditions to be very readily investigated. The character of the sky polarization, with its general symmetry and maximum in a plane at 90? solar distance, is well known, but the nature and causes of its casual variations have not, perhaps, received the attention that is their due. Nearly everything in the landscape polarizes by reflection to a greater or less extent, the more as the specular component of reflection is the greater. For example, the glossy upper surface of a maple leaf polarizes strongly at fairly large angles of incidence, while the mat lower surface has only

Note on Some Meteorological Uses of the Polariscope

This is merely a preliminary notice of certain facts regarding atmos pheric polarization which may prove to have some prognostic value. They were incidental to a proposed study of the character of autumnal haze which the writer undertook last year at Mount Moosilauke, N. H. This peak, 4811 feet high, has an almost uninterrupted sweep of horizon over a radius of one hundred miles or so and offers an excellent chance for investigating the distribution and nature of the haze that veils the landscape in early autumn. For instruments I took along a Savart polariscope, merely a Savart plate with a bit of tourmaline as analyzer, an extemporized double-image polarimeter of the type outlined in the early and valuable paper of Professor E. C. Pickering,1 a couple of carefully calibrated photographic wedges for determining opacities, and a direct vision spectroscope. A prolonged easterly storm, about the only thing which could have defeated the program, cut short observations upon the summit, but a week of preliminary observations at Breezy Point (elevation 1650 feet) at the base of the mountain yielded results which seem to be of suffi cient interest to put upon record. These were made mostly with the Savart polariscope, an instrument which, from its very wide field of view and great sensitiveness, showing even one or two per cent of polarization, enables sky conditions to be very readily investigated. The character of the sky polarization, with its general symmetry and maximum in a plane at 90? solar distance, is well known, but the nature and causes of its casual variations have not, perhaps, received the attention that is their due. Nearly everything in the landscape polarizes by reflection to a greater or less extent, the more as the specular component of reflection is the greater. For example, the glossy upper surface of a maple leaf polarizes strongly at fairly large angles of incidence, while the mat lower surface has only

Method of Observing the “Subjective Yellow.”

A SIMPLE method of obtaining the sensation of yellow produced by the mixture of red and green lights is afforded by a small direct-vision spectroscope of the ordinary kind in which the slit can be rotated to adjust its line perpendicular to the plane, of refraction. If the slit is turned slowly, from this normal position, the bands, of different colours, of course, take up a sloping direction across the spectrum, like books on a half-filled shelf. As the slope increases, the upper end, for example of the red, closes down on the lower end of the green, and as the two blend the clear yellow tint is produced. Other colour mixtures can be similarly noticed.

XXXIII. Direct-vision spectroscope of one kind of glass

(1903). XXXIII. Direct-vision spectroscope of one kind of glass. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science: Vol. 6, No. 32, pp. 268-270.

Direct-Vision Spectroscope of one kind of Glass

Direct-Vision Spectroscope of one kind of Glass

Societies and Academies

LONDON. Physical Society, April 26.—Dr. R. T. Glazebrook, foreign secretary, in the chair.—A paper on the thermodynamical correction of the gas thermometer was read by Prof. H. L. Callendar. This paper commences by giving a short historical sketch of the thermodynamic correction of the gas thermometer, describing some of the solutions to Thomson's fundamental equation for the Joule-Thomson plug experiment. The assumptions made in the solutions have sometimes been erroneous and wrong corrections have been obtained. From 1885 to 1888 Chappuis made a series of careful comparisons between various gas thermometers and a very delicate mercury thermometer, and drew up a table of differences between the hydrogen and the nitrogen thermometer. The author has taken the observations of Chappuis and calculated a new table of differences. The index “n”in the modified Joule-Thomson equation is not constant. For steam it is about 3.5 and for carbonic acid about 2. The thermodynamic correction is very small, especially in the case of hydrogen and helium, and is very much less than the correction for the expansion of the thermometer bulb. Prof. Herschell asked whether the co-volume came into the correction. Dr. Harker looked forward to the experiments which Prof. Callendar proposes to make with a constant pressure thermometer. The chairman expressed his interest in the extreme delicacy of the observations of Chappuis.—A paper on the production of a bright-line spectrum by anomalous dispersion and its application, the “flash-spectrum,” by R. W. Wood, was read and experimentally illustrated by Mr. Watson. It has been suggested by W. H. Julius that the “flash-spectrum seen immediately at totality may be due to photosphere light abnormally refracted in the atmosphere of metallic vapours surrounding the sun. The light which will be thus abnormally refracted will be of wave lengths almost identical with the wave-lengths which the metallic vapours are themselves capable of radiating. The sun is supposed t be surrounded by an atmosphere of metallic vapours, the refractive index of which decreases with increasing distance from the surface. In this atmosphere the rays of light coming from the photosphere move in curved paths. The refractive index is, however, very small, except for wave-lengths very near those absorbed by the vapour, consequently the light which resembles that emitted by the vapours, is most strongly refracted, and therefore curves sufficiently to reach us after the photosphere has been hidden by the moon. The flash-spectrum of sodium was shown by focussing the light of an arc lamp on a horizontal slit in front of a flat metal plate supported so that the plane in which its under-suriace lay coincided with the plane of the slit. At a distance of about two metres a direct vision spectroscope was arranged to give a vertical spectrum and placed at such a height that the prism barely caught the rays coming from the slit and grazing the plate. On looking into the spectroscope a bright continuous spectrum is seen. A Bunsen burner was then placed underneath the metal plate and fed with sodium. This produced a layer of sodium vapour of varying refractive index. On raising or lowering the spectroscope bright sodium lines are seen due to anomalous dispersion. By arranging screens these lines can be obtained so that, on cutting out the arc lamp, the flash-spectrum vanishes. Prof. Herschel expressed his interest in the experiments and their application to the case of the flash-spectrum seen at totality.

On the spectroscopic examination of colour produced by simultaneous contrast

In a previous communication I have described some methods of using the spectroscope to analyse sensations of successive contrast. In those experiments the eye, after having been fatigued by monochromatic—preferably spectral—light, is exposed to a second stimulus, consisting also of spectral light, exciting one or more colour-sensations which may or may not include that fatigued by the primary sensation. The question naturally arises, whether the spectroscopic method might not be applied to problems of simultaneous contrast. With this view I made a number of experiments with the Marlborough spectroscope during the summer of 1897, of which the following may be mentioned. A piece of thin cover-glass was fixed in front of the eye-piece at an angle of 45° with the optic axis, so as to reflect into the field of view a small complete spectrum furnished by a 3½ inch direct-vision spectroscope. In order that this might be visible against the bright field of the larger spectroscope, a glass disc, with an opaque spot of the required size painted on it, was inserted in the eye-piece close to the diaphragm.

Some Contributions to the Spectroscopy of Hæmoglobin and its Derivatives

1. Apparatus.—The following are needed:—Electric or lime light; standard hæmatinometer (i.e., of 1 cm. between the parallel sides) entirely of glass (for many pigments white glass flat-sided stoppered bottles do perfectly well); large direct-vision spectroscope (Messrs Hilger), or a Tollen's carbon-disulphide glass prism (base 5 inches, refracting angle 45°); a well-stretched dead-white screen to receive the spectrum 4 feet long at least, about 12 feet from the lantern.Following Preyer (1), one can with such apparatus first of all demonstrate the different spectroscopic appearance according as blood is or is not diluted. Placing blood newly received from the slaughter-house (defibrinated blood) in the hæmatinometer, we show that it is opaque in a thick layer, no light passes to the prism at all, there is no spectrum, we can say that the percentage of HbO2 is, at least, greater than 7·3. Dilute with pure cold water until a faint gleam of red light appears at the extreme left, the concentration of HbO2 is now not less than 1 per cent.; continue the dilution until the first glimmer of extra-linear green appears, the percentage is now about ·9 per cent.; dilute until the first glimmer of intra-linear green appears, when the percentage is now ·7; add to this its own volume of water, making the percentage fall to ·35. From this point further dilution caused progressive faintness of the two bands, until the vanishing point of the fainter β band is just reached when the hæmoglobin is ·01 per cent.; continue the attenuation until the α band is alone visible, at which point the percentage can be stated to be certainly less than ·01 per cent.