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キーワード:
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要旨:
We applied three different LA systems (213 nm nanosecond solid state,
193 nm nanosecond excimer, and 200 nm femtosecond laser) coupled to a
quadrupole ICP-MS or a sector field ICP-MS, respectively, for the
analysis of different sulfide minerals (pyrrhotite, chalcopyrite, and
sphalerite). Ablation craters were investigated via back-scattered
electron (BSE) images to compare the amounts of melt produced, and
fractionation factors were calculated to determine the degree of
down-hole fractionation. Our results show significant differences in
melting between the three LA systems. While samples show massive melting
when using the ns systems, no melting has been observed utilizing the fs
laser. Fractionation factors for a variety of elemental pairs indicate
the absence of down-hole fractionation even at the highest melt
production. The extent of melting of different sulfide specimens is
independent of melting temperatures of these materials. Although no
down-hole fractionation has been observed, Fe/S fractionation as
calculated from sensitivities deviate among pyrrhotite and chalcopyrite
when applying the 193 nm ns and 200 nm fs systems. Analyses of synthetic
pyrrhotite with known PGE concentrations using the 200 nm fs LA system
yielded moderately precise and accurate concentration data (3-4%; 4-14%
2SD) utilizing sulfide as the external reference material. Application
of NIST610 as the reference material improved the precision to 1.4-2.4%
2SD and the deviation from reference values to 5-7%.
