scholarly journals The L emission series of mercury

1926 ◽  
Vol 111 (757) ◽  
pp. 117-124 ◽  
Keyword(s):  
Atomic Number ◽  
Emission Lines ◽  
Heavy Elements ◽  
Inherent Difficulty ◽  
Liquid Mercury ◽  
Active Elements ◽  
The Face ◽  
Hot Filament ◽  
Filament Type

The L emission series of most of the heavy elements from ytterbium to uranium have been investigated by Coster and by Dauvillier, but their tables of results do not include measurements for some of the radio-active elements and for mercury. Muller, in 1921, by means of a tube of the “gas-filled” type and a liquid-mercury target, overcame the inherent difficulty regarding mercury, viz., that of the rapid volatilization of the mercury from the face of the anticathode. It has been found possible to prepare targets amalgamated with mercury which are sufficiently lasting to enable their use in a tube of the hot filament type; by this means measurements of the wave-lengths of the emission lines have been made with an accuracy exceeding that of Muller. In addition, several new lines have been measured, and an attempt made to clear up a certain amount of confusion which exists regarding the designation of some of the lines of the L spectra of elements of higher atomic number.

scholarly journals Infrared Emission-Lines and the Stellar Temperature

1993 ◽  
Vol 155 ◽  
pp. 89-89 ◽  
Author(s):  
Sueli M. Viegas ◽  
Ruth Gruenwald
Keyword(s):  
Near Infrared ◽  
Planetary Nebulae ◽  
Infrared Emission ◽  
Emission Lines ◽  
Heavy Elements ◽  
Atomic Transitions ◽  
Stellar Temperature ◽  
Near Infrared Emission

Observations of near infrared emission-lines are becoming available and can be a powerful tool to improve our knowledge on planetary nebulae properties. For wavelengths in the range 1 to 5 μm, the emission-lines correspond to atomic transitions of high ionized species of heavy elements. In particular, the [Si VI] 1.96μm and [Si VII] 2.48μm lines have already been detected (Ashley and Hyland, 1988).

scholarly journals Letter to the Editor: Comments on “Compositional Averaging of Backscatter Intensities in Compounds,” with a Response from Donovan

2003 ◽  
Vol 9 (6) ◽  
pp. 491-492
Author(s):  
S.J.B. Reed
Keyword(s):  
Atomic Number ◽  
Mass Fraction ◽  
Averaging Method ◽  
Heavy Elements ◽  
Backscatter Coefficient ◽  
X Ray ◽  
Rigorous Testing ◽  
Electron Backscatter ◽  
New Thinking ◽  
The Difference

The electron backscatter coefficient (η) and the related correction factor for X-ray intensity (R) are both strongly dependent on atomic number and although quite good data are available for pure elements, the derivation of values for compounds is problematic. This issue is addressed by Donovan, Pingitore, and Westphal (Microscopy and Microanalysis, Vol. 9, No. 3, June 2003, pp. 202–215), in which an “electron fraction” averaging method is advocated as an improvement on “traditional” mass fraction averaging, which is known to be only an approximation. (The difference, according to Table 3, is only significant, however, for samples containing heavy elements such as Pb and Th.) New thinking on this topic is welcome, but I believe this proposal should be treated with caution pending more rigorous testing.

Areas for Improvement in XRF Analysis of Low Atomic Number Elements

1992 ◽  
Vol 36 ◽  
pp. 73-80
Author(s):  
Bruno A.R. Vrebos ◽  
Gjalt T.J. Kuipéres
Keyword(s):  
Lower Limit ◽  
Atomic Number ◽  
Energy Dispersive Spectrometry ◽  
Limit Of Detection ◽  
Heavy Elements ◽  
Fluorescence Spectrometry ◽  
Accurate Analysis ◽  
X Ray ◽  
Made In

Accurate analysis of the light elements has been, from the early applications of X-ray fluorescence spectrometry a struggle compared to the determination of heavy elements in the same matrices. In contrast, there has been virtually no upper limit to the atomic number of the element that could be determined. The lower limit, however, has been continuously adjusted downward through the years. Clearly, the sensitivity as well as the lower limit of detection for the heavy elements have also been improved, but the effect is Jess striking than the advances made in the region of tight element performance. This paper deals specifically with wavelength dispersive sequential x-ray fluorescence spectrometry, although some of the observations made are equally applicable to energy dispersive spectrometry.

Heavy, Superheavy . . . Quo Vadis?

2018 ◽  
Author(s):  
Paul J. Karol
Keyword(s):  
Atomic Number ◽  
Periodic Table ◽  
Chemical Element ◽  
Chemical Elements ◽  
Chemical Properties ◽  
Superheavy Element ◽  
Electron Shell ◽  
Heavy Elements ◽  
Quo Vadis ◽  
Definition Of

Uranium was Discovered in 1789 by the German chemist Martin Heinrich Klaproth in pitchblende ore from Joachimsthal, a town now in the Czech Republic. Nearly a century later, the Russian chemist Dmitri Mendeleev placed uranium at the end of his periodic table of the chemical elements. A century ago, Moseley used x-ray spectroscopy to set the atomic number of uranium at 92, making it the heaviest element known at the time. This chapter will deal with the quest to explore that limit and heavy and superheavy elements, and provide an update on where continuation of the periodic table is headed and some of the significant changes in its appearance and interpretation that may be necessary. Our use of the term “heavy elements” differs from that of astrophysicists who refer to elements above helium as heavy elements. The meaning of the term “superheavy” element is still not exactly agreed upon and has changed over the past several decades. “Ultraheavy” is occasionally used. Interestingly, there is no formal definition of “periodic table” by the International Union of Pure and Applied Chemistry (IUPAC) in their glossary of definitions: the “Gold Book.” But there are plenty of definitions in the general literature—including Wikipedia, the collaborative, free, internet encyclopedia which calls the “periodic table” a “tabular arrangement of the chemical elements, organized on the basis of their atomic numbers, electron configurations (electron shell model), and recurring chemical properties. Elements are presented in order of increasing atomic number (the number of protons in the nucleus).” IUPAC’s first definition of a “chemical element” is: “A species of atoms; all atoms with the same number of protons in the atomic nucleus.” Their definition of atom: “the smallest particle still characterizing a chemical element. It consists of a nucleus of positive charge (Z is the proton number and e the elementary charge) carrying almost all its mass (more than 99.9%) and Z electrons determining its size.”

scholarly journals Polarized Line Profiles in Planetary Nebulae

1993 ◽  
Vol 155 ◽  
pp. 231-231
Author(s):  
J.R. Walsh ◽  
R.E.S. Clegg
Keyword(s):  
Indirect Evidence ◽  
Planetary Nebulae ◽  
Emission Lines ◽  
Symmetric Pattern ◽  
Near Ir ◽  
First Results ◽  
The Face ◽  
Polarization Profiles ◽  
Ir Emission ◽  
Bright Emission

There is much direct and indirect evidence for the presence of dust in Planetary Nebulae (PN): variations in extinction across the face of the nebulae; IR emission with strong 25 and 60μm fluxes; broad near-IR emission lines of Silicate, SiC and PAH grains; optically thick lines, such as [C IV]1550Å, have lower strength on account of the increased path length due to dust scattering; a centro-symmetric pattern of polarization vectors in a few PN (Leroy et al., A&A, 160, 171, 1986). An observational programme has begun to study the polarization profiles of bright emission lines in PN arising from dust scattering within the nebulae. The first results are discussed.

scholarly journals The absorption of hard monochromatic γ -radiation.—Part II

1932 ◽  
Vol 135 (826) ◽  
pp. 223-237 ◽  
Keyword(s):  
Atomic Number ◽  
Heavy Elements ◽  
Absorption Coefficients ◽  
Γ Radiation ◽  
Quantum Energy ◽  
High Quantum ◽  
Γ Ray ◽  
Very High ◽  
Considerable Intensity

Thorium C" emits in very considerable intensity a monochromatic γ-ray of very high quantum energy (2·649 × 10 6 e -volts) free from any other radiation of quantum energy greater than 0·786X 10 6 e -volts, so that it can be isolated by filtering through a few centimetres of lead. Experiments by Tarrant, Meitner and Hupfeld, Chao and by Jacobsen on the absorption of these rays are in agreement in leading to the conclusion that the scattering formula of Klein and Nishina is a good approximation for the elements of low atomic number. The absorption coefficients of the heavy elements, however, indicate that a new mode of γ-ray absorption is occurring, which may be nuclear in origin.

Deuteron bombardment of the heavy elements.

1940 ◽  
Vol 36 (4) ◽  
pp. 490-499 ◽  
Author(s):  
R. S. Krishnan ◽  
E. A. Nahum
Keyword(s):  
Atomic Number ◽  
Lead Isotope ◽  
Lead Isotopes ◽  
Absorption Measurement ◽  
Hard Work ◽  
Radioactive Isotopes ◽  
Heavy Elements ◽  
High Atomic Number ◽  
Deuteron Bombardment ◽  
Made In

The results of the bombardment of mercury, lead and thallium by 9 M.e.V. deuterons are reported. The following radioactive isotopes have been detected: 5·5 min., 48 min., 36 hr., 60 day mercury isotopes; 4·4 min., 10·5 hr., 44 hr., and 13 day thallium isotopes; 10·25 min., 2·75 hr., and 54 hr. lead isotopes; 18 hr. and 6·35 day bismuth isotopes. The 10·25 min. lead isotope is positron emitting, an interesting result in an element of high atomic number. Absorption measurement have been made of the radiations emitted by many of these isotopes and assignments have been made in most cases.In conclusion we wish to thank Dr N. Feather for valuable discussions, and also for making for us a Ra E source. We are indebted to Dr Lewis for advice in setting up the thyratron scale of eight counter. This paper would be incomplete without a sincere acknowledgement of our indebtedness to the hard work of past members of this laboratory who have been mainly responsible for setting up the cyclotron.One of us (R. S. K.) is grateful to the Royal Commissioners for the Exhibition of 1851 for the grant of an overseas scholarship which made this work possible.

THE ABSORPTION OF GAMMA-RAYS FROM Co60

1947 ◽  
Vol 25a (6) ◽  
pp. 303-314 ◽  
Author(s):  
W. V. Mayneord ◽  
A. J. Cipriani
Keyword(s):  
Absorption Coefficient ◽  
Atomic Number ◽  
Gamma Rays ◽  
Heavy Elements ◽  
Photoelectric Absorption ◽  
Lead Absorber ◽  
Absorption Coefficients ◽  
Cobalt Radiation ◽  
Good Agreement ◽  
Made In

Measurements of the absorption of gamma-rays from Co60 and radium have been made in a number of materials. Variation of absorption coefficient of the gamma-rays from radium with thickness of lead absorber is in agreement with recent experimental determinations. The gamma-rays from Co60 are approximately monochromatic and are therefore suitable for testing theoretical absorption formulae. The absorption coefficient per electron for materials of atomic number equal to or less than that of aluminium was in agreement with the Klein–Nishina formula, assuming the cobalt radiation to consist of two lines at 1.10 and 1.30 Mev. respectively. The photoelectric absorption coefficients per electron for heavy elements are in good agreement with the theory developed by Hulme, McDougall, Buckingham, and Fowler. This coefficient varies approximately as Z3.5.

Going Nondispersive

1998 ◽  
Vol 4 (6) ◽  
pp. 552-558
Author(s):  
Kurt F.J. Heinrich ◽  
Ray Fitzgerald ◽  
Klaus Keil
Keyword(s):  
Solid State ◽  
Energy Range ◽  
Atomic Number ◽  
Energy Resolution ◽  
Electron Probe ◽  
Emission Lines ◽  
Crystal Spectrometer ◽  
X Ray ◽  
State Detection ◽  
The One

The energy-dispersive Si(Li) X-ray spectrometer, introduced 30 years ago into electron probe mi-croanalysis (EPMA) by R. Fitzgerald et al., has profoundly affected the development of microanalysis. It offers many advantages over the wavelength-dispersive crystal spectrometer. It has no moving parts and covers the full energy range of interest in EPMA. There is no defocusing over large distances on the specimen, the efficiency of the device is high, varies slowly and continuously with atomic number, and can be predicted fairly accurately, and, most importantly, all emission lines are detected and can be observed simultaneously. The one remaining disadvantage of the Si(Li) spectrometer is its poorer energy resolution. Solid-state detection devices now under development promise to achieve resolution comparable to that of the crystal spectrometer.

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