Kevin,

Good timing on your reply.  I have my computer here with me today so I can
look up some of my results for CO2 laser attacks on barite with BrF5.

If you have not seen it, there is a Hoering and Rumble GCA paper ('95 or
'94) on the techniques used at Carnegie Geophysical Lab.  As part of the
procedure we clean the gas in a small GC.  This allows us to also look at
what else we have made during the operation.  The barite I tried to analyze
is a natural specimen of moderate temperature hydrothermal origin, thus it
could have had some impurities.  the GC strip showed a rather sizable CO2
peak (origin unknown) followed by a tiny SF6 peak and then by a very large
SO2F2 peak, which amounted to >95% of the peak integration for the 2 S
compounds.  It appears that no SOF2 was generated.  I also experimented on
alunite (KAl3(SO4)2(OH)6) of a similar origin and got roughly similar
results, but this time about 25% of the S counts were from SOF2, but SO2F2
was still the dominant S gas, and SF6 < 5% of the total S.  This is in
contrast to natural sulfides, which generate a small amount of CO2 (again
of unknown origin), trace amounts of SO2F2 and SOF2 (likely from oxide
coatings on the sulfide surface), and a bunch of SiF4 (important to
ventilate to the fume hood, or at least through some moisture).  If you are
getting 40% yield of SF6 that is much better than I was able to get, so
maybe there is hope for laser heating of sulfates.

Bob
Regards,

Bob Ilchik
Department of Geosciences
University of Arizona
Tucson, AZ  85721
(520) 621-9792 (W)
(520) 621-2672 (FAX)
(520) 881-2002 (H)