Mercury Lines Research Articles

Performance of an Eight-Inch Babcock Grating in a Large Vacuum Spectrograph

To obtain true profiles of Fraunhofer lines, corrections for instrumental profile, ghosts, scattered light, etc., must be applied to the observations. A study of a 600 groove/mm Babcock grating in a high dispersion, vacuum spectrograph (8 mm/A, 5th order, λ 5461) is presented. Photographs of the hyperfine structure of the mercury line λ 5769 show a resolution of 630 000 in the 5th order. Photographs of Hg λ 2536 with a microwave-excited 198 lamp as a source exhibit a weakly self-reversed line. The measured separation of the components is 0.0021 A, corresponding to a resolving power of 1 200 000 in the 11th order. The instrumental profile, the intensities of satellite lines, and the ghost system have been determined by photoelectric scanning of the line λ 5461 of isotopic mercury. A determination of the vertical apparatus function shows that its half width is 15% wider than the theoretical value. The total intensity of the ghosts is 1.8% in the 5th order. A brief study of polarization effects and the nature of the blaze is presented. The general spectrographic scattered light was found to be 0.7%.

Fluorescence spectrophotometry of reduced phosphopyridine nucleotide in intact cells in the near-ultraviolet and visible region

An apparatus is described with which it is possible to measure precisely fluorescence spectra, not only of clear solutions, but also of a scattering weakly fluorescent suspension of living cells or pieces of tissue, in the region 350–600 mω by excitation with the mercury line 313 mω and in the region 400–600 mω by excitation with 366 mω. Fluorescence spectra of free DPNH, suspensions of baker's yeast, Photobacterium phosphoreum and Photobacterium splendidum, and the alga Chlorella were determined. When excited by carefully filtered light of 366 mω, all three species showed fluorescence spectra presumably caused mainly by reduced pyridine nucleotide. Measurements of the time course of the fluorescence of starved yeast upon addition of ethanol and glucose indicated that this fluorescence was for the main part caused by reduced phosphopyridine nucleotide. The method appears to be more specific and more generally applicable than absorption spectrophotometry for the measurement of reduced pyridine nucleotide in vivo.

Spectres continus moléculaires et atomiques d'émission du mercure

Using the electrodeless discharge as an excitation method much information can be obtained about the mechanism of spectral emission. This discharge enables the successive emission of spectra, obtained simultaneously with any other excitation method. In this way the continuous spectrum of mercury vapour in the range 6400 Å–2200 Å was studied, using damped and undamped waves. Using undamped waves the following spectra were obtained: (1) the arc-lines of mercury. (2) continuous spectra: C I from 5800–4100 Å G II from 3650–3100 Å C III over the entire range studied. (3) unresolved band-spectra: S 1 from 5265–5015 Å S 2 from 4721–4491 Å S 3 from 4312–4132 Å Using damped waves: (1) arc and spark lines of mercury (2) continuous spectra C I and C II as mentioned above and C IV over the entire range studied like C III, but probably with a different emission-mechanism. A systematic study of these spectra (effect of vapour pressure, temperature, excitation voltage) confirmed previous results. Moreover, using undamped waves we observed: (1) The continuous spectrum C III which might be due to the coexistence in the same part of the discharge tube of two recombination-processes. (a) recombination of an ionized atom and an electron. (b) recombination of an ionized molecule and an electron. (2) Three diffuse band series, observed in the continuum C III, probably due to the transitions of the molecular states 6 1 S 0 + 7 1 D 2, 6 1 S 0 + 8 1 D 2, 6 1 S 0 + 9 1 D 2 to 6 1 S 0 + 6 1 P 1. The third series from 4312 to 4132 was mentioned already. It was possible to distinguish the molecular spectra C I and C II by their relative vertical position in the same spectrogram; the first time in our opinion that the excitation gradient in electrodeless discharge was used in the field of molecular spectra to separate the spectra of different excitation types.

Über die Rolle der Stufenübergänge bei Anregung von Spektrallinien

In the simplest case of excitation of spectral lines by a beam of electrons of homogeneous velocity passing through a vapour under low pressure the intensity of a line I may be defined by an equation. For the purpose of working out the effect of stepwise transitions the author together with I.P. Sapesotchny performed experiments on defining the intensity of the mercury lines as a function of the energy of exciting electrons. The presence of several maxima in the optical excitation function is explained by the effect of stepwise transitions. Every experimental curve with several maxima can be expanded into curves representing excitation functions of single energy levels of mercury atoms. The excitation functions of single energy levels have a sharp maximum placed but a few tenths of a volt higher than the critical potential. There is no distinct difference between the appearance of the excitation function of singlet mercury level and that of a triplet mercury level.

Spectroscopic observations on commercial preparations of cytochrome c.

IT is generally agreed that reduced cytochrome c shows absorption bands in the visible spectrum at 550 mµ (α-band) and at 520 mµ (β-band); in fact, the presence of these two absorption bands is the principal means of detecting reduced cytochrome c in a biological object. Keilin and Hartree1 have observed the absorption bands of cytochrome cdissolved in 50 per cent glycerol and in the vitrified or devitrified states at the temperature of liquid air or oxygen, a procedure by which the absorption bands can be intensified and sharpened; under these conditions they report that a fine satellite band appears next to the α-band on its short-wave side, and the β-band appears to be a complex of several peaks. In connexion with studies on the cytochrome absorption bands of Protozoa2, we have examined the absorption bands of two commercial preparations of cytochrome c (beef heart, salt-free, Sigma Chemical Co.; Boehringer und Sohne, Mannheim) using the liquid-air cooling technique of Keilin and Hartree. A0.07 per cent (w/v) solution of Sigma cytochrome c and a 0.2 per cent (w/v) of Boehringer cytochrome c in 70 per cent (v/v) glycerol buffered at pH 7.0 with 1/50 M phosphate were either oxidized with potassium ferricyanide (2.5 m.M) or reduced with sodium sulphoxylate (in excess) and examined in the liquid state (23° C.) and after cooling to −196° C. in liquid nitrogen in a flattened ‘Pyrex’ tube (light path approximately 5 mm.). The higher concentration of the Boehringer cytochrome c was necessary in order to reach the same degree of absorption (O.D. 0.4) as the Sigma preparation at 550 mµ. 70 per cent glycerol proved to be more satisfactory than the 50 per cent used by Keilin and Hartree for observation of the absorption lines. The observations were made with a Zeiss Mikro-Specktralokular (Abbe) using a carbon arc lamp (Phywe 8150) as the source of light, and placing the cytochrome preparation above the microscope condenser. With the vitrified material the observations were completed within 30 sec. after removal from the liquid nitrogen. The spectroscope scale was standardized against the mercury line at 546 mµ. Both commercial preparations of cytochrome c showed exactly the same extinction bands, and the results in Table 1 therefore apply to both.

Motion and Spectrum of Arc Cathode Spot in a Magnetic Field

The velocity of the cathode spot of a mercury arc at the junction between liquid and metal in a transverse magnetic field has been measured for magnetic field strengths between 0 and 20 700 oersteds. The approximate doubling of retrograde velocity at about 11 000 to 15 000 oersteds was followed by an additional rapid rise of velocity at about 15 000 oersteds. Spectra of the arc showed Hg ii and Hg iii lines at the stronger magnetic fields. Radiation from the cathode spot showed mercury lines and a continuous spectrum which is especially intense at the lines. Some Hg lines are broadened symmetrically and others asymmetrically. If the broadening is due to a Stark effect, the electric field strength in the cathode spot region is greater than 6\ifmmode\times\else\texttimes\fi{}${10}^{6}$ volts/cm.The arc mechanism previously proposed is extended to explain the rapid velocity rises with increasing magnetic field strength by associating them with the effect of ${\mathrm{Hg}}^{++}$ and ${\mathrm{Hg}}^{+++}$ ions.

A Filter Transmitting near the Mercury Line, 2537 A

A Filter Transmitting near the Mercury Line, 2537 A

Equivalent Network Representations for Solid and Mercury Delay Lines

An equivalent network representation is derived for mercury and solid delay lines. A transfer function that relates output voltage to input voltage is the quantity selected to represent the delay line, and this transfer function is derivable from a matrix equation. Mercury and solid delay lines are compared in terms of the gain band width product of the delay line. The comparison extended to include factors not present in the circuit representation. Other topics discussed are third-time-around signals, acoustic transformers, glued crystals, input impedance, wave propagation, and diffraction. The final selection between solid and mercury delay lines is determined by the specific application.

A Filter Transmitting near the Mercury Line of λ 2537 Å

A Filter Transmitting near the Mercury Line of λ 2537 Å

The Determination of the Intensities of Raman Lines*

Existing methods for the quantitative evaluation of Raman line intensities are briefly reviewed and attention is called to the desirability of obtaining intensity data which permit comparisons between laboratories using different apparatus. A simple method for obtaining such data is described, using the 459 cm−1 Raman line of CCl4 as a reference and eliminating the properties of the spectrometer and detector by a calibration with the radiation from an incandescent lamp which was standardized as Illuminant A by the National Bureau of Standards. The calibration is tested by calculating the intensity ratios of Stokes to anti-Stokes lines and also the ratios of pairs of Raman lines when excited by two mercury lines. Consistency with theory is found which indicates that the method of calibration is satisfactory.

Raman Spectra of Several Compounds Containing Phosphorus

Raman spectra of water solutions of NaH2PO2, KH2PO2, HPO3, NaPO3, K4P2O7, K2Na2P2O7, K2H2P2O7, and Na2H2P2O7 were photographed using a Hilger constant-deviation spectrograph. Illumination was provided by four Hanovia mercury lamps, the 4358A line being used as the exciting radiation. A system of liquid filters reduced the effect of the other mercury lines so that their presence was not objectionable. A Wollaston prism made possible the separation of the perpendicular and parallel components of the scattered radiation. Intensity and depolarization values were calculated from traces obtained by means of a Kipp and Zonen microphotometer. The Raman spectra of the NaH2PO2 and KH2PO2 solutions were identical, while those of the HPO3 and NaPO3 solutions differed markedly from each other. The spectra of the four pyrophosphate solutions were all similar in appearance, and their spectral lines showed similar relative intensities and depolarization values. Suggested models have been postulated.

Raman Effect of the Isomers of Benzene Hexachloride

IN the course of our research programme on the structure of molecules, we have photographed the Raman lines of the pure alpha, beta, gamma and delta isomers of benzene hexachloride (C6H6Cl6) dissolved in benzene. The lines were photographed with a Steinheil GH three-prism spectrograph specially fitted for Raman work (collimator, f = 195 mm.; camera, f = 255 mm.). The lines were excited by the mercury line 4358 A. by means of a Heræus No. S700 lamp.

Interference Measurements in the Spectra of Neon and Natural Mercury

Accepted neon standards cover the region 6929–5852A. We have observed the first spectrum of neon throughout the region 8919–3126A in order to assist in establishing secondary standards in that part of this range where none exist.The first spectrum of natural mercury was observed from 7020 to 2200A in order to discover in what part of this range standards of suitable intensity will be available when lines emitted by Hg198 have been measured; and to find out which lines (if any) of the natural element may serve as standards when mercury is accidently or unavoidably present in a low pressure source. It is shown that some lines of natural mercury are suitable for secondary standards, and nearly all may be useful when an accuracy of no more than a part per million is required.

Coefficients of Reflection in the Ultraviolet of Magnesium Carbonate and Oxide

The coefficients of reflection of magnesium carbonate and magnesium oxide have been determined for eight mercury lines in the ultraviolet. A spectrometer made up of a Rowland grating furnished a spectrum of light reflected from a part-sphere of the material under test. A photo-multiplier tube received the spectrum. The materials are both good reflectors, the oxide being especially good since it is over 0.90 at all points tested.

Studies on the refractive index and dispersion of American tung oil

Conclusions Tung oil has a refractive index and a dispersion so far above those of any other common oil that both are valuable criteria for identification purposes. With proper equipment the dispersion, in addition to the refractive index, can be determined with little extra effort and would confirm the conclusions drawn from the refractive index. Mixtures of tung oil with another vegetable oil (except oiticica and other rare conjugated oils) can be analyzed to within 0.5% from the refractive index for either the sodium or the mercury line if the refractive indices of the separate oils are known. The mixtures can be analyzed from the dispersion to within about 1% of the correct composition if the dispersions of the separate oils are known. If the adulterating oil is not known the adulteration can be more closely estimated from the depression of the dispersion than from the depression of the refractive index. When tung oil is bodied by heat the refractive indices for the sodium and mercury lines and the dispersion fall rapidly and continuously to the point of gelation, but the changes are so similar that no worth‐while additional information is obtained by determining more than one refractive index. The fact that refractive index decreases as viscosity increases suggests the use of the refractive index in controlling the bodying of tung oil. Other things being equal, the refractive index for the mercury line should give more accurate information on tung oil than that for the sodium line because of the greater changes in the refractive index for the mercury line upon adulteration or heating. A correlation coefficient of 0.83 was found for refractive index with the diene number of tung oil. A lower correlation coefficient was found for refractive index with the iodine number, but the latter would probably be higher if a more accurate method for the determination of the iodine number of tung oil were available.

On interference microscopy.

Interference microscopy provides a method of increasing the visibility of specimens which are colourless and which differ slightly in refractive index from the surrounding medium by enclosing them between semi-reflecting surfaces, which thus constitute an interferometer. In making observations by this method, it is necessary to use monochromatic light or light of two different wave-lengths, which can be isolated conveniently by the use of a mercury-arc lamp with appropriate filters. This method owes its inception to Frederikse (1933), and has been further developed by the writer in a recent communication (Merton 1947). When monochromatic light falls normally on a pair of semi-reflecting surfaces which are parallel to one another, the intensity of the light which is transmitted is a function of the separation of the plates and, owing to the effect of multiple reflexions, a curve in which intensity is plotted against separation shows a succession of maxima the width of which, in relation to the minima between them, depends on the reflecting power of the semi-reflecting surfaces. The introduction of a body of different refrac­tive index between the plates is optically equivalent to changing their separation with the result that if the plates are at a distance such that the transmission is a maximum, a small change in refractive index is sufficient to cause a great decrease in the transmission. In such a case the body would be seen as a dark object on a bright background. For other separations of the plates the reverse may occur and the body may be seen bright on a dark background. When two radiations (e. g. the green and violet lines of mercury) are used simultaneously it frequently occurs that the object appears in one colour and the background in another.

Infra-Red and Raman Spectrum of Cyclo-octatetraene

As part of work on the structure and properties of cyclo-octatetraene, we have recently measured the infra-red spectrum between 2µ. and 20µ of the liquid and vapour and the Raman spectrum of the liquid. The sample was prepared specially for this purpose, and purified by repeated re-crystallization. The infra-red spectra were measured with single- and double-beam recording spectrometers using prisms of rock salt, fluorite and potassium bromide. The Raman spectrum was excited with the mercury line 5461 A., which lies to the long wave-length side of the onset of absorption, and photographed with a spectrograph having a large glass prism giving high resolution and medium dispersion.

Production ofHg198as a Possible Source of an Improved Wave-Length Standard

The green line 5461A from any of the even isotopes of mercury is superior, in many respects, to the red line 6438A of cadmium for a primary standard of wave-length. The mercury isotope of mass 198 was produced by utilizing the nuclear transformation $_{79}\mathrm{Au}^{197}+_{0}n^{1}\ensuremath{\rightarrow}_{80}\mathrm{Hg}^{198}+_{\ensuremath{-}1}\ensuremath{\beta}^{0}$One ounce of pure gold was sealed in a quartz tube and a section of 5-mm inside diameter quartz tube was sealed on the quartz-gold tube. The system was outgassed and 4-mm Hg pressure of spectroscopically pure argon was admitted and the tube was sealed. The gold was exposed to stray neutrons near the sixty-inch cyclotron for ten months. The gold was then heated and the mercury was condensed in the 5-mm quartz tube. The mercury vapor in the presence of argon gas was excited by means of a 100-megacycle oscillator and the spectrum was observed. The lines produced by the discharge were mercury lines, and the position of the lines of a Fabry-Perot etalon spectrogram agree with the position assigned by Sch\"uler and Jones to the mercury isotope of mass 198. Larger quantities of gold exposed to known superior sources of neutrons will produce an adequate supply of the isotope for scientific purposes.

Absolute Scotopic Sensitivity of the Eye in the Ultra-violet and in the Visible Spectrum

IN a paper published in 19411 measurements were given of scotopic and photopic sensitivity, for which nine observers were used. These measurements were made in the range between the mercury lines 709 and 302 mμ. In the paper by Goodeve, Lythgoe and Schneider published in 19422 measurements were given of scotopic sensitivity, for which six observers were used, including one with an aphakic eye. Their measurements were made at the mercury lines at 365 and 546 mμ. It is of interest to compare the results obtained after dark adaptation of one hour, with the results of Goodeve et al., obtained after dark adaptation for 10 minutes.

Fluorescence Spectra of Naphthacene Molecules in Solid Solution of Anthracene with the Variation of Wave-lengths

MR. GANGULY'S observations, which are in complete accord with those of several other workers on the subject1, can scarcely be said to refute the idea of energy transfers in crystals. Solid naphthacene fluoresces with its characteristic band emission, though rather faintly; when dissolved in solid anthracene it also fluoresces, as Mr. Ganguly notes, if illuminated by light which is directly absorbed by naphthacene molecules (4350–4000 A.). The vital question in the matter of energy transfer is what happens when shorter-wave light is used. If the mercury line at 3650 A. is used for excitation, the green fluorescence of naphthacene is visible in solid solutions containing only one molecule of naphthacene in 105 molecules of anthracene; at 1 in 104 this green fluorescence is strong, and above about 5 in 104 the green is brilliant while the violet anthracene fluorescence has disappeared. At 3650 A. anthracene absorbs much more strongly than naphthacene; the extinction coefficients in liquid solution are 1600 and 400 respectively, so that unless the ratio of extinction coefficients changes by a factor of about 104 in passing from solution to solid, the light must be absorbed by the anthracene molecules.