Design of an infrared monochromatic system with an AOTF as the dispersion element

Author(s):  
Feng Wan ◽  
Shifu Fan
Keyword(s):  
2001 ◽  
Vol 52 (1) ◽  
pp. 25 ◽  
Author(s):  
Allison F. Britt ◽  
Raymond E. Smith ◽  
David J. Gray

Much of the Australian regolith ranges from Palaeogene to Late Cretaceous in age or even older, contrasting with the relatively young landscapes of the Northern Hemisphere. Hence, many imported geochemical exploration methods are unsuitable for Australian environments; this has led to successful homegrown innovation. Exploration geochemistry seeks to track geochemical anomalies arising from concealed ore deposits to their source. Much is known about element associations for different types of ore deposits and about observed patterns of dispersion. Element mobility in a range of Western Australian environments is discussed, drawing on field examples from the Mt Percy and Boddington gold mines and the Yandal greenstone belt, with reference to the effect of modern and past weathering regimes and the influence of groundwater on element mobility. Soil biota and vegetation affect Au mobility in the regolith, but specific processes, scale and environmental factors are unknown. Possible future synergies between biogeochemical or environmental research and regolith exploration geochemistry include determining the fundamental biogeochemical processes involved in the formation of geochemical anomalies as well as environmental concerns such as regolith aspects of land degradation. Exploration geochemists must study the work of biogeochemical and environmental researchers, and vice versa. There should also be collaborative research with regolith scientists and industry.


2005 ◽  
Vol 30 (10) ◽  
pp. 1102 ◽  
Author(s):  
Chao-Wei Lee ◽  
Ruibo Wang ◽  
Pochi Yeh ◽  
Chao-Hsing Hsieh ◽  
Wood-Hi Cheng

1988 ◽  
Vol 49 (5) ◽  
pp. 1135-1139
Author(s):  
A. L. Levit ◽  
V. I. Malarev ◽  
V. M. Ovchinnikov ◽  
V. G. Parfenov

1989 ◽  
Vol 53 (371) ◽  
pp. 357-362 ◽  
Author(s):  
Philip J. Potts ◽  
Andrew G. Tindle

AbstractThe analytical characteristics of a W/Si multilayer dispersion element (MLDE) with a nominal 2d spacing of 60 Å are assessed and compared with those of a conventional thallium acid phthalate (TAP) crystal for the determination of fluorine in silicate and phosphate minerals by electron microprobe. Measured count rates for fluorine were found to be up to fourteen times higher using the MLDE compared with TAP giving improved detection limits of 0.02 to 0.08 wt. % F (six sigma, 100s count time) compared with equivalent data of 0.06 to 0.12 wt. % F by TAP. At equivalent spectrometer angles, peak widths by MLDE were broader by a factor of 2 to 3. However, an important advantage of MLDE was found to be the absence of multiple order diffractions higher than the second order. In consequence, the troublesome third order P-Kα line interference on the F-Kα line, normally encountered in the analysis of apatites, is absent in determinations made using the MLDE. Conversely small interferences on the F-Kα line were detected from the first-order Lα line of Fe and second-order Lα line of Mg. X-ray data and spectra of selected minerals are presented to demonstrate these interferences. Detection limits for elements that can also be determined using the MLDE were 0.07 to 0.15 wt. % oxygen and 0.34 wt. % carbon.


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