On Titanium for a Comparison Spectrum

1899 ◽  
Vol 10 ◽  
pp. 207
Author(s):  
Edwin B. Frost
Keyword(s):  
Comparison Spectrum

scholarly journals XIX. On the photographic arc spectrum of iron meteorites

1894 ◽  
Vol 185 ◽  
pp. 1023-1028
Keyword(s):  
Royal Society ◽  
Solar Spectrum ◽  
British Museum ◽  
Iron Meteorites ◽  
Electrolytic Iron ◽  
Comparison Spectrum ◽  
Size And Shape ◽  
Previous Communication ◽  
Oxyhydrogen Flame ◽  
Made In

In a communication to the Royal Society in 1887, I gave an account of certain experiments which I had made in connection with the spectra of various meteorites at various temperatures. The spectra were observed at the temperature of the oxyhydrogen flame and the electric spark without jar, and when glowed in vacuum tubes. Some larger specimens of the iron meteorites, Nejed and Obernkirchen, cut so that they were of a size and shape suitable for forming the poles of an arc lamp, having afterwards been kindly placed at my disposal by the Trustees of the British Museum, it became possible to study the arc spectra of these meteorites under very favourable conditions, all impurities introduced by the use of the carbon poles being thus avoided. The region of the spectrum photographed extends from K to D, in the case of each meteorite, and in addition to the solar spectrum, that of electrolytic iron, prepared by Professor Roberts-Austen, referred to in a previous communication, has been used as a comparison spectrum in one case.

Thorium Comparison Spectrum

1975 ◽  
Vol 29 ◽  
pp. 97 ◽  
Author(s):  
James B. Breckinridge ◽  
A. Keith Pierce ◽  
Clifford P. Stoll
Keyword(s):  
Comparison Spectrum

scholarly journals The Calibration of Stellar Spectra Used in Measurements of the Generalized Compton Shift

1985 ◽  
Vol 111 ◽  
pp. 595-597
Author(s):  
M. Missana
Keyword(s):  
Spectral Range ◽  
Planetary Nebula ◽  
Thomson Scattering ◽  
Compton Effect ◽  
Spectral Lines ◽  
Comparison Spectrum ◽  
Stellar Spectra ◽  
The Continuum

In the study of the changes induced by the Compton effect and Thomson scattering on the shape of spectral lines in light traversing a chromosphere or a planetary nebula it is necessary to have accurate wavelength measurements, central intensities and half widths (FWHM) of the lines. In the comparison of FWHM measures belonging to different spectra it is useful to have the intensities of the continuum at the wavelengths of the lines. The studied spectra should have a dispersion higher than 10 Å/mm and a spectral range larger than 700 Å. A short recommendation is also given about the comparison spectrum and the calibration plate.

scholarly journals On Fuzzy Soft Linear Operators in Fuzzy Soft Hilbert Spaces

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Nashat Faried ◽  
Mohamed S. S. Ali ◽  
Hanan H. Sakr
Keyword(s):  
Hilbert Space ◽  
Hilbert Spaces ◽  
Shift Operator ◽  
Point Spectrum ◽  
Soft Set ◽  
Linear Operators ◽  
Comparison Spectrum ◽  
Left Shift ◽  
Definition Of ◽  
Soft Point

Due to the difficulty of representing problem parameters fuzziness using the soft set theory, the fuzzy soft set is regarded to be more general and flexible than using the soft set. In this paper, we define the fuzzy soft linear operator T~ in the fuzzy soft Hilbert space H~ based on the definition of the fuzzy soft inner product space U~,·,·~ in terms of the fuzzy soft vector v~fGe modified in our work. Moreover, it is shown that ℂnA, ℝnA and ℓ2A are suitable examples of fuzzy soft Hilbert spaces and also some related examples, properties and results of fuzzy soft linear operators are introduced with proofs. In addition, we present the definition of the fuzzy soft orthogonal family and the fuzzy soft orthonormal family and introduce examples satisfying them. Furthermore, the fuzzy soft resolvent set, the fuzzy soft spectral radius, the fuzzy soft spectrum with its different types of fuzzy soft linear operators and the relations between those types are introduced. Moreover, the fuzzy soft right shift operator and the fuzzy soft left shift operator are defined with an example of each type on ℓ2A. In addition, it is proved, on ℓ2A, that the fuzzy soft point spectrum of fuzzy soft right shift operator has no fuzzy soft eigenvalues, the fuzzy soft residual spectrum of fuzzy soft right shift operator is equal to the fuzzy soft comparison spectrum of it and the fuzzy soft point spectrum of fuzzy soft left shift operator is the fuzzy soft open disk λ~<~1~. Finally, it is shown that the fuzzy soft Hilbert space is fuzzy soft self-dual in this generalized setting.

scholarly journals On temperature and pressure regulation in prismatic spectrographs

1927 ◽  
Vol 113 (765) ◽  
pp. 704-708 ◽  
Keyword(s):  
Refractive Index ◽  
Electric Heating ◽  
Barometric Pressure ◽  
Resolving Power ◽  
Comparison Spectrum ◽  
University Of Wisconsin ◽  
Light Gathering Power ◽  
Light Gathering ◽  
The University ◽  
Source Of Error

It is well known that displacements of spectrum lines during a photographic exposure can be caused by changes in the temperature of the dispersing apparatus and of the air in the spectrograph. In the case of grating instruments elaborate precautions are sometimes taken to keep the room in which the spectrograph is housed at a constant temperature. Birge* has described the precautions taken at the University of Wisconsin, where the grating spectrograph is mounted in a double-walled room, the space between the walls being kept constant by suitable electric heating. In the photography of faint spectra prismatic spectrographs are sometimes to be preferred to gratings on account of their superior light-gathering power, and it is of importance to consider the errors in measurement and loss of definition due to variations in temperature. The change in refractive index with temperature appears to vary rather considerably with different melts of glass. Giffordf has measured the temperature coefficients for a series of glasses in air, and his results show that these are positive for all the glasses investigated, with one exception, Fluor Crown, which would not be suitable for the construction of prisms for spectrographs. The change in refractive index per degree Centigrade for glasses of the type suitable for the construction of prisms is shown to be of the order of 5 X 10 -6 , and since for a typical glass at λ = 5875 A, the change per Ångstrom unit is 9 X 10 -6 , the shift in wavelength per degree Centigrade would be upwards of half an Ångström unit. The temperature coefficient of some glasses seems to be considerably greater than the above value. Displacements of spectrum lines are also effected by changes in the barometric pressure during long exposures. There are, of course, many days on which this effect may be neglected, but this source of error does not appear to have received the attention that it merits. The refractive index of air at 760 mm. pressure and 20° C. is about 1•000275, so that if we assume that n p = n 760 — [( n — 1) (760 — p)/760] the change in n per cm. pressure is about 3·6 X 10 -6 , and taking the change in n per Ångström unit at D 3 as 9 X 10 -6 , we expect a shift of about 0·4 A per cm. pressure. A change in pressure as great as 1 cm. during the course of an exposure would be unusual,but changes exceeding 1 mm. are not infrequent during long exposures, and it is evident that they cannot be ignored. It is usual to expose the comparison spectrum, comprising the lines of standard wavelength, either simultaneously with the spectrum under investigation, or in instalments at regular intervals, but it has been shown that errors due to displacements* can only be eliminated in this way in the case of lines which are symmetrical, and in any case there is a loss of definition and resolving power with a loss of accuracy of the settings in the course of measurement. The experiments described in this communication relate to a prism spectrograph recently constructed for the writer by Messrs. Adam Hilger, and although the methods adopted and the conclusions reached seem fairly obvious, they may be worthy of record in view of the fact that satisfactory results were obtained only after trials extending over many months, and the details of construction appear to be of vital importance.

scholarly journals Quantitative Two-Dimensional Classifications of Low Dispersion Objective Prism Spectra

1978 ◽  
Vol 80 ◽  
pp. 29-32
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
List Type ◽  
Spectral Features ◽  
Two Dimensional ◽  
Type Number ◽  
Comparison Spectrum ◽  
Stellar Spectra ◽  
Quantitative Measurements ◽  
Light Losses ◽  
Objective Prism ◽  
Low Dispersion

The objective prism (or grating) is the most efficient stellar spectrograph since it suffers no light losses at a slit and - compared to a slit spectrograph - only small losses in the camera optics. However, objective prism spectra have two principal disadvantages:(1)the spectral resolution (and consequently the sharpness of spectral features) depends on the seeing, which may vary from plate to plate.(2)quantitative measurements are difficult because of the difficulty in obtaining an exact photographic calibration; no comparison spectrum can be placed near the stellar spectra.

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