The Fine Structure and the Wave-Length of the Balmer Lines

1926 ◽  
Vol 64 ◽  
pp. 81 ◽  
Author(s):  
William V. Houston
Keyword(s):  
Fine Structure ◽  
Wave Length ◽  
Balmer Lines

scholarly journals Interferential comparison of the red and other radiations emitted by a new cadmium lamp and the michelson lamp

1933 ◽  
Vol 139 (837) ◽  
pp. 202-218 ◽  
Keyword(s):  
Fine Structure ◽  
High Temperature ◽  
Wave Length ◽  
The Other ◽  
Reference Standard ◽  
Definite Evidence ◽  
Electro Magnetic ◽  
The Many ◽  
Red Radiation ◽  
Red Line

It is now generally recognised that future definitions of the units of length will probably be based on the length of a wave of visible light. At present the wave-length of the red radiation of cadmium serves as the basis of all measurements of the lengths of electro-magnetic waves which are perceptible by optical means, and provisional sanction has been given to measurements of length on the same basis, as an alternative to direct reference to the metre. Whether the cadmium red radiation provides the best reference standard for all measurements of length has not yet been definitely established. Two international committees, one representing spectroscopists and the other metrologists, have sanctioned standard specifications for cadmium lamps of the Michelson type from which the red radiation may be produced. The two specifications differ from one another in certain details, but both are subject to the same objections. These objections are directed partly against the high temperature at which it is necessary to run the lamp and partly against the high voltage required to excite the radiation. Therefore, such hyperfine structure and asymmetry as may be present in the red line of cadmium is likely to be masked in the Michelson lamp by a combination of two phenomena —the enhanced Doppler effect due to the high temperature of the radiating cadmium atoms, and the effect of the moderately high intensity of the electric field. Were this not so, it might be somewhat surprising that no definite evidence of fine structure or asymmetry had so far been observed in the red line from the Michelson lamp, notwithstanding the many careful examinations, with the aid of the most sensitive interferometers, to which this line has been subjected, in view of its importance as the reference standard for all other wave-lengths. Recently Nagaoka and Sugiura have recorded that they have observed slight evidences of structure in the red radiation when excited under special conditions in which great precautions were taken to ensure extreme sharpness of the line. It is believed, however, that no subsequent confirmation of this effect has yet been published.

scholarly journals Hour-timescale profile variations in the broad Balmer lines of the Seyfert galaxy Hour-timescale profile variations in the broad Balmer lines of the Seyfert galaxy Markarian 6

2013 ◽  
Vol 9 (S304) ◽  
pp. 407-408
Author(s):  
Norayr S. Asatrian
Keyword(s):  
Fine Structure ◽  
Emission Line ◽  
Sampling Rate ◽  
Seyfert Galaxy ◽  
Special Astrophysical Observatory ◽  
Balmer Line ◽  
Line Profiles ◽  
Balmer Lines ◽  
Profile Changes ◽  
Hydrogen Emission Line

AbstractPart of results of the multi-epoch intranight optical spectroscopic monitoring of the Markarian 6 nucleus carried out at the telescopes of 6-m of the Special Astrophysical Observatory (Russia), 2.6-m of the Byurakan Astrophysical Observatory (Armenia) and 2-m of the Tautenburg Observatory (Germany) is presented.Observations were made in 1979, 1986, 1988-1991 and 2007-2009 during a total of 33 nights with an average sampling rate of 4 spectra per night. TV-scanner and long-slit spectrographs equipped with Image Tube and CCD detector arrays were used. Altogether we analyzed 110 Hβ and 58 Hα region spectra to search for intranight variability in the broad hydrogen emission line profiles. The typical spectral resolutions were 4 Å for scanner spectra, 6 Å for photographic spectra, and 5 Å and 10 Å for CCD spectra. The S/N ratio at the continuum level near the Hβ and Hα lines was in the range 15–50.The purpose of the search was to look for the characteristic variability signatures of different kinematical models of the broad emission-line region. We considered the centering and guiding errors which can result in differences between spectra.We found variations in the broad Balmer line difference profiles on time scale of hour with the level of significance of 3.6 σ to 5.0 σ. Variations take the form of narrow, small bumps located at the blue and red sides or only at the blue side of the lines. In the intermediate level of broad line flux, the Hβ and Hα profiles show fine structure. Detected profile changes occurred at the same radial velocity shifts as the details in the fine structure.The variability is at least 2 orders of magnitude more rapid than any observed for broad Balmer line profiles in AGNs that we are aware of in the literature.Discovered extremely rapid line-profile variability may be associated with reverberation effects. Two-sided profile changes may indicate the response of circularly rotating hydrogen clouds in the BLR to a light pulse from a central source. One-sided profile variations may be attributed to a response of a non-disk component: the subarcsec scale region of the jet.

The Fine Structure of the Balmer Lines

1934 ◽  
Vol 45 (4) ◽  
pp. 263-272 ◽  
Author(s):  
W. V. Houston ◽  
Y. M. Hsieh
Keyword(s):  
Fine Structure ◽  
Balmer Lines

Vibration-rotation bands of nitrous oxide

1951 ◽  
Vol 208 (1094) ◽  
pp. 326-331 ◽  
Keyword(s):  
Nitrous Oxide ◽  
Fine Structure ◽  
Ground State ◽  
Wave Length ◽  
The Other ◽  
Resolving Power ◽  
Microwave Measurements ◽  
Rotational Constants ◽  
Infra Red ◽  
Vibration Rotation

The infra-red absorption of nitrous oxide gas near 4·5 μ has been re-investigated using high resolving power. The rotational fine structure has been split up and shown to involve two vibrational transitions, one due to absorption of a fundamental from the ground state, and the other to a π → π transition from an excited vibrational level. The transitions have been analyzed theoretically and rotational constants obtained. The results serve to emphasize the importance of using more precise wave-length standards for infra-red measurements than have been used hitherto, if the rotational constants are to be obtained with accuracy com­parable to that achieved by microwave measurements. Excellent agreement with the latter has now been found.

scholarly journals Some investigations in röntgen spectra. Part III. -Fine structure of K-absorption edge of SiO 2

1931 ◽  
Vol 131 (818) ◽  
pp. 654-658 ◽  
Keyword(s):  
Fine Structure ◽  
Silicon Oxide ◽  
Wave Length ◽  
High Vacuum ◽  
Short Wave ◽  
X Rays ◽  
Pure Silicon ◽  
Short Wave Length ◽  
Low Dispersion ◽  
Made In

It is now well known from the works of Lindh, Fricke and others that the principal K or L edge is attended on its short wave-length side by a number of secondary edges. The usual method of obtaining this structure consists in putting absorbing screens in the path of X-rays before or after they are analysed by a suitable crystal. The chief difficulty in this is the preparation of absorbing screen of suitable thickness. Fricke as well as Lindh have used this method for the study of absorption spectra of several substances. The former author failed to obtain any K-absorption limit at all for silicon. This was probably due to his using thick absorbing screens coupled with the low dispersion which he obtained with a sugar crystal. Later Lindh succeeded in obtaining K-limits for both silicon and silicon oxide, and showed that as in so many other cases the K-edge of pure silicon is softer than that of the compound. He, however, did not succeed in getting any fine structure. The probable cause of this was again the use of screens of unsatisfactory thickness. This difficulty may be avoided by using the analysing crystal itself as an absorber when a suitable crystal is available. Lindsay and Van Dyke used this method successfully to study the fine structure of the calcium K-edge in calcite, gypsum and fluorite crystals. Nuttall has made partial use of this method in his study of structure of K-absorption edges of potassium and chlorine. Later Lindsay and Voorhees made use of this method to study the fine structure for different crystals containing iron. Following the same method the fine structure for silicon oxide was photographed and measured by using quartz as the analysing and absorbing crystal. The apparatus used was a high vacuum spectrograph of Professor Siegbahn’s design made in the laboratory workshop. Its adjustment and use is described in Part I. The continuous radiation was obtained from a tungsten anticathode formed by dovetailing a plate of this material on the copper anticathode which as already described had four sides.

Fine structure and spectral broadening of Balmer lines in laser-produced plasmas

1979 ◽  
Vol 20 (6) ◽  
pp. 2574-2581 ◽  
Author(s):  
P. Nicolosi ◽  
G. Tondello ◽  
E. Jannitti
Keyword(s):  
Fine Structure ◽  
Spectral Broadening ◽  
Balmer Lines

Experimental Study of the Stark Broadened Helium Ion Lines Hell 121.5, 164.0 and 468.6 nm

1984 ◽  
Vol 39 (11) ◽  
pp. 1041-1048 ◽  
Author(s):  
A. Piel ◽  
J. Slupek
Keyword(s):  
Experimental Study ◽  
Fine Structure ◽  
High Purity ◽  
Laser Interferometer ◽  
Plasma Parameters ◽  
Line Shapes ◽  
Helium Ion ◽  
Balmer Lines ◽  
Theoretical Line ◽  
Coupled Cavity

Using a pulsed linear discharge of high purity, Stark broadened profiles of the first two Balmer lines and the Paschen-α line of HeII have been investigated. The electron density (Ne = 5.5 · 1022 m-3) was measured with a coupled cavity He-Ne laser interferometer. The intensity ratio of the HeII 468.6 nm and the HeI 471.3 nm line was employed to determine the electron temperature (Te = 3.8 eV). At these plasma parameters the measured ion lines are unaffected by self absorption. This enables direct comparison with existing theories. Discrepancies between experimental and theoretical line shapes are critically discussed. Fine structure effects, usually neglected in theories, turn out to be important for the Balmer-α line.

scholarly journals Fine-structure of soft X-ray absorption edges - I—Li, Mg, Ni, Cu metals

1937 ◽  
Vol 161 (906) ◽  
pp. 420-440 ◽  
Keyword(s):  
Fine Structure ◽  
Conduction Electron ◽  
Wave Length ◽  
Ultra Violet ◽  
Short Wave ◽  
Experimental Investigations ◽  
X Rays ◽  
X Ray ◽  
X Ray Absorption

The borderland region between ultra-violet light and X-rays, particularly from about 100 to 300 A, is very suitable for obtaining spectroscopic information regarding the electronic structure of metals, or solids generally. The first step towards this problem consists in the determination of the intensity distribution in the soft X-ray emission bands, which represent transitions from the filled conduction-electron levels of a metal into a vacant inner shell. We thus obtain information relating to the distribution with energy of these filled levels. The most complete experimental investigations of the emission bands are those of Siegbahn and Magnusson (1934) and of O’Bryan and Skinner (1934) for the metals Li, Be, Na, Mg, Al, Si. Subse­quent work showed that the extension of these results to heavier metals is very difficult, because the Auger effect reduces the intensity of the emission by a large factor. The complementary problem is that of absorption, in which we are dealing with transitions from an inner shell of the metal into one of the unoccupied conduction-electron levels of the metal. The probability of such an absorption process is closely connected with the density of the unoccupied levels as a function of energy. The experimental problem therefore consists of the determination of the variation in the absorption coefficient of radiation by electrons of a given inner shell as a function of wave-length; or, as it may be called, the determination of the fine-structure on the short wave-length side of an X-ray absorption edge of a metal.

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