Raman Spectroscopy - a Study of Iron Sulfate Minerals

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.

Autorentext

Chi Hong Chio completed his PhD in Chemistry from University ofHawaii. His dissertation research is the study of temperature andpressure induced structural changes in ferrous sulfate hydratesand jarosites using micro-Raman spectroscopy. He is alsointerested in the application of remote Raman techniques fordetection of various substances.

Klappentext

Raman spectroscopy has been used to study hydrous sulfate minerals of importance to planetaryscience. These minerals are the mono-, tetra- andheptahydrates of ferrous sulfate and minerals of thejarosite group including Na-, K- and NH4-jarosite.Each mineral has its characteristic spectrum that canbe used for remote identification on planetarysurfaces and is important in the study ofpast geological environment. Effects from the watersof crystallization and hydrogen bonding on the Ramanspectra of ferrous sulfate hydrates have beenstudied. Structural changes and phase transitions inthese hydrates under cryogenic temperatures and highpressures have been studied. In the study ofjarosites, the variations observed in the Ramanspectra at room temperature and cryogenictemperatures are discussed in terms of changes inunit cell dimensions influenced by differentinterlayer cations. The Raman and IR spectra ofK-jarosite after heating to 230 and 400 °C showed thepresence of yavapaiite, which was also detected inthe Raman spectra of K-jarosite at room temperatureunder reduced water vapor pressure in conditions thatcan be found on the surface of Mars.