Core polarisation effect on the 3p 1/2, 3p 3/2, 2f 5/2, 2f 7/2 and 1i 13/2 proton states of209Bi

1985 ◽  
Vol 322 (4) ◽  
pp. 641-645 ◽  
Author(s):  
R. Majumdar
Keyword(s):  
Polarisation Effect ◽  
Core Polarisation

scholarly journals An Impedance Study of the Membrane Polarisation Effect in Simulated Rock Systems

2021 ◽  
Author(s):  
◽  
Michael Charles Harold McKubre
Keyword(s):  
Low Frequency ◽  
Impedance Measurement ◽  
Impedance Analysis ◽  
Laboratory Model ◽  
Pore Geometry ◽  
Impedance Spectra ◽  
Clay Rock ◽  
Polarisation Effect ◽  
Diffusional Limitation ◽  
Electrochemical Model

<p>Work is reported on the development of a high precision, low frequency impedance bridge, and the use of impedance measurement in characterising the induced polarisation effect of unmineralised material. Impedance spectra for a variety of laboratory model clay/rock/electrolyte systems are analysed in terms of an equivalent circuit. By measuring the dependence of the parameters of this circuit, on such variables as electrolyte type and concentration, temperature and pore geometry, an electrochemical model for membrane polarisation has been developed. Polarisation is considered to arise from diffusional limitation of cations at the membrane/electrolyte interface of clay aggregations in rock pores, and this is found to be amenable to a Warburg diffusional impedance analysis.</p>

1.3-Dithienium-and 1.3-Dithiolenium Salts, VI ,13C NMR Spectroscopic Investigations on 2-Substituted 1,3-Dithian-2-ylium Cations. Unusual γ-Effects

1997 ◽  
Vol 52 (6) ◽  
pp. 757-761 ◽  
Author(s):  
Hans-Otto Kalinowski ◽  
Ingfried Stahl
Keyword(s):  
Electric Field ◽  
Density Distribution ◽  
13C Nmr ◽  
Field Effect ◽  
Electron Density Distribution ◽  
Chemical Shifts ◽  
Membered Ring ◽  
Electric Field Effect ◽  
Polarisation Effect ◽  
C Nmr

Abstract The 13C NMR chemical shifts of 19 2-substituted 1,3-dithian-2-ylium-tetrafluorborates 1a-1s are discussed in comparison to known analogous 1,3-dithianes and 2-lithio-1,3-dithianes. The unusual γ-effects (up to 9 ppm), which can also observed in other six-membered ring systems, are explained by the electric field effect (σ-polarisation effect). The electron density distribution can be estimated qualitatively by comparison with the 1,3-dioxan-2-ylium-and cyclohexylcations.

scholarly journals Studies of iridescent colour, and the structure producing it. III.—The colours of labrador felspar

1923 ◽  
Vol 103 (720) ◽  
pp. 34-45 ◽  
Keyword(s):  
Point Of View ◽  
Polished Surface ◽  
Magnetic Oxide ◽  
Golden Yellow ◽  
Total Reflexion ◽  
Polarisation Effect ◽  
The Subject

The brilliant colours displayed by reflexion at certain angles from a polished surface of labradorite, or Labrador felspar, have long been known, and specimens of the material are to be seen in most mineral collections. Several investigations of the origin of these colours have been published, but I must confess that I have not been able to get clear ideas by studying them. The writers approach the subject primarilly from the mineralogist's point of view, and much mineralogical detail is introduced which seems doubtfully relevant and (to me at least) difficult to follow. Vogelsang's conclusion (translated) is: "The results of my investigations, so far as they concern the various colourations of labradorite, may be summarised as follows: A blue reflexion, due to a polarisation effect, is peculiar to a certain crystalline condition of the mineral. A golden yellow results from total reflexion on the included microlites, which consist of magnetic oxide of iron or of diallage as well; the association of these extraneous colouring matters and of the bluish reflexion on the cleavages accounts for the green or violet chatoyance; . . ."

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