scholarly journals Absolute intensity of the aurora line in the night sky, and the number of atomic transitions required to maintain it

1930 ◽  
Vol 129 (811) ◽  
pp. 458-467 ◽  
Keyword(s):  
Continuous Spectrum ◽  
Angular Size ◽  
Absolute Intensity ◽  
High Accuracy ◽  
Resolving Power ◽  
Green Line ◽  
Atomic Transitions ◽  
Absolute Determination ◽  
Night Sky

Some time ago Prof. S. Chapman, F. R. S., pressed upon me the importance of making an absolute determination of the intensity of the auroral green line in the night sky, in order to fix the number of atomic transistions per second required to maintain it. Such a determination will be of value even if not of high accuracy value, high accuracy is out of the question. The difficulty of the problem arises from the faintness of the light of the auroral line, and the fact that it is not isolated but superposed on a background of apparently continuous spectrum, from which it cannot in the nature of the case be completely separated without the use of high spectroscopic resolving power. The last usually involves loss of light and restriction of the angular size of the photometric field. There is too little light to begin with to allow of this.

scholarly journals On the absorption of λ 5460.97 A. by luminous mercury vapour

1922 ◽  
Vol 102 (714) ◽  
pp. 33-45 ◽  
Keyword(s):  
Continuous Spectrum ◽  
Resolving Power ◽  
Central Portion ◽  
Mercury Vapour ◽  
High Grade ◽  
Green Line ◽  
Electric Currents ◽  
Quartz Mercury ◽  
Original Line

Numerous investigators who have studied the structure of the mercury green line λ 5460.97 A. have found that it consists of a wide central unresolved band, flanked on either side by three or more clearly resolved components that are usually designated as satellites. Janicki has shown, however, and so has Nagaoka, that the central portion of the line can be resolved into well defined components when a Lummer plate of high resolving power is used by itself, or is crossed with another of the same kind, or with a high grade échelon spectrograph. From such investigations it would appear to be definitely settled that the line is produced by twelve separable and distinct wave-lengths. These components, as measured by Nagaoka, are shown in their relative positions, and with approximately their relative intensities, in fig. 1. The values of their relative wave-lengths, as measured by Janicki and Nagaoka, are given in Table I. In their investigations on the structure of the line λ 5460.97 A., Janicki, Prince Galitzin and Wilip, Stansfield and one of the writers found that, when an Heraeus quartz mercury arc lamp was used as the source of light (and also when other forms of lamps were used as well), the structure of the line underwent a profound modification when the radiation was produced by the passage of very heavy electric currents in place of weak ones. Janicki observed, in place of the original line and its satellites, a peculiar system of five equidistant bands, the original components of the line being apparently lost in a continuous spectrum.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

Experimental Determination of the Effective Resolution Limit in Thick Specimens at High Voltages

1975 ◽  
Vol 33 ◽  
pp. 664-665
Author(s):  
Mircea Fotino
Keyword(s):  
Experimental Approach ◽  
Chromatic Aberration ◽  
Resolving Power ◽  
Biological Research ◽  
Specimen Thickness ◽  
Resolution Limit ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Resolution Level

The use of thick specimens (0.5 μm to 5.0 μm or more) is one of the most resourceful applications of high-voltage electron microscopy in biological research. However, the energy loss experienced by the electron beam in the specimen results in chromatic aberration and thus in a deterioration of the effective resolving power. This sets a limit to the maximum usable specimen thickness when investigating structures requiring a certain resolution level.An experimental approach is here described in which the deterioration of the resolving power as a function of specimen thickness is determined. In a manner similar to the Rayleigh criterion in which two image points are considered resolved at the resolution limit when their profiles overlap such that the minimum of one coincides with the maximum of the other, the resolution attainable in thick sections can be measured by the distance from minimum to maximum (or, equivalently, from 10% to 90% maximum) of the broadened profile of a well-defined step-like object placed on the specimen.

scholarly journals The Degree of Oxidation of Graphene Oxide

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 560
Author(s):  
Alexandra Carvalho ◽  
Mariana C. F. Costa ◽  
Valeria S. Marangoni ◽  
Pei Rou Ng ◽  
Thi Le Hang Nguyen ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Ab Initio ◽  
State Of The Art ◽  
High Accuracy ◽  
Precise Determination ◽  
Photoemission Spectroscopy ◽  
Pristine Graphene ◽  
X Ray ◽  
Degree Of Oxidation

We show that the degree of oxidation of graphene oxide (GO) can be obtained by using a combination of state-of-the-art ab initio computational modeling and X-ray photoemission spectroscopy (XPS). We show that the shift of the XPS C1s peak relative to pristine graphene, ΔEC1s, can be described with high accuracy by ΔEC1s=A(cO−cl)2+E0, where c0 is the oxygen concentration, A=52.3 eV, cl=0.122, and E0=1.22 eV. Our results demonstrate a precise determination of the oxygen content of GO samples.

Electrochemical device based on nonspecific DNAzyme for the high-accuracy determination of Ca2+ with Pb2+ interference

2020 ◽  
pp. 107732
Author(s):  
Hui Wang ◽  
Qingyao Luo ◽  
Yiguang Zhao ◽  
Xuemei Nan ◽  
Fan Zhang ◽  
...  
Keyword(s):  
High Accuracy ◽  
Electrochemical Device ◽  
Accuracy Determination

Based on Atomic Spectrometry for the Determination of Titanium Element in Molten Steel

2012 ◽  
Vol 622-623 ◽  
pp. 1528-1531
Author(s):  
Cui Hong Ma ◽  
Wei Qiang Zhang
Keyword(s):  
Molten Steel ◽  
Emission Spectroscopy ◽  
Atomic Emission ◽  
Lag Time ◽  
High Accuracy ◽  
Atomic Spectrometry ◽  
Atomic Emission Spectrometry ◽  
Emission Spectrometry ◽  
Important Significance

Atomic emission spectrometry with high accuracy, short lag time, and low detection limit, it has been widely applied in various fields. The application of atomic emission spectrometry in the converter steelmaking process has an important significance to improve the smelting of speed and steel quality. This article describes the principle of atomic emission spectroscopy (AES) analysis. Spectra obtained by the experimental for qualitative analysis, detected molten steel containing titanium element.

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