Raman spectroscopy has been used to study hydrous
sulfate minerals of importance to planetary
science. These minerals are the mono-, tetra- and
heptahydrates of ferrous sulfate and minerals of the
jarosite group including Na-, K- and NH4-jarosite.
Each mineral has its characteristic spectrum that can
be used for remote identification on planetary
surfaces and is important in the study of
past geological environment. Effects from the waters
of crystallization and hydrogen bonding on the Raman
spectra of ferrous sulfate hydrates have been
studied. Structural changes and phase transitions in
these hydrates under cryogenic temperatures and high
pressures have been studied. In the study of
jarosites, the variations observed in the Raman
spectra at room temperature and cryogenic
temperatures are discussed in terms of changes in
unit cell dimensions influenced by different
interlayer cations. The Raman and IR spectra of
K-jarosite after heating to 230 and 400 °C showed the
presence of yavapaiite, which was also detected in
the Raman spectra of K-jarosite at room temperature
under reduced water vapor pressure in conditions that
can be found on the surface of Mars.
Chi Hong, Chio.
Chi Hong Chio completed his PhD in Chemistry from University of
Hawaii. His dissertation research is the study of temperature and
pressure induced structural changes in ferrous sulfate hydrates
and jarosites using micro-Raman spectroscopy. He is also
interested in the application of remote Raman techniques for
detection of various substances.