Étude des surstructures de la magnétorésistance de InSb

1987 ◽  
Vol 65 (5) ◽  
pp. 468-475 ◽  
Author(s):  
J. Galibert ◽  
P. Perrier ◽  
S. Askenazy ◽  
R. A. Stradling ◽  
P. R. Wallace
Keyword(s):  
Longitudinal Optical ◽  
Landau Levels ◽  
Second Derivative ◽  
Optical Phonons ◽  
Transverse Magnetoresistance ◽  
Method Of Determination ◽  
Spin Flip ◽  
Magnetophonon Resonance

We have carried out experiments of magnetophonon resonance on n-InSb doped at 4.6 × 1013 cm−3 at a temperature of 135 K. The second derivative of longitudinal and transverse magnetoresistance exhibits obviously spin-resolved peaks of magnetophonon resonances involving one or two longitudinal optical phonons. Among these "over-structures" appear spin-flip resonances, particularly the 0−0+ resonance.The structures of the magnetoresistance are explained from the calculation of resonance fields, based on our method of determination of the Landau levels.

Development of a method for multielemental determination in water by EDXRF with radioisotopic source of 238Pu.

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Camilo Fuentes Serrano ◽  
Juan Reinaldo Estevez Alvares ◽  
Alfredo Montero Alvarez ◽  
Ivan Pupo Gonzales ◽  
Zahily Herrero Fernandez ◽  
...  
Keyword(s):  
Thin Layer ◽  
Expanded Uncertainty ◽  
Considerable Decrease ◽  
X Ray ◽  
Precipitation Efficiency ◽  
Method Of Determination ◽  
Sensitivity Curves ◽  
Order Of Magnitude ◽  
Metrological Parameters

A method for determination of Cr, Fe, Co, Ni, Cu, Zn, Hg and Pb in waters by Energy Dispersive X Ray Fluorescence (EDXRF) was implemented, using a radioisotopic source of 238Pu. For previous concentration was employed a procedure including a coprecipitation step with ammonium pyrrolidinedithiocarbamate (APDC) as quelant agent, the separation of the phases by filtration, the measurement of filter by EDXRF and quantification by a thin layer absolute method. Sensitivity curves for K and L lines were obtained respectively. The sensitivity for most elements was greater by an order of magnitude in the case of measurement with a source of 238Pu instead of 109Cd, which means a considerable decrease in measurement times. The influence of the concentration in the precipitation efficiency was evaluated for each element. In all cases the recoveries are close to 100%, for this reason it can be affirmed that the method of determination of the studied elements is quantitative. Metrological parameters of the method such as trueness, precision, detection limit and uncertainty were calculated. A procedure to calculate the uncertainty of the method was elaborated; the most significant source of uncertainty for the thin layer EDXRF method is associated with the determination of instrumental sensitivities. The error associated with the determination, expressed as expanded uncertainty (in %), varied from 15.4% for low element concentrations (2.5-5 μg/L) to 5.4% for the higher concentration range (20-25 μg/L).

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