title: Raman spectroscopy of halotrichite from Jaroso, Spain.
abstract: Raman spectroscopy complimented with infrared ATR spectroscopy has been used to characterise a halotrichite FeSO(4) x Al(2)(SO(4))(3) x 22 H(2)O from The Jaroso Ravine, Aquilas, Spain. Halotrichites form a continuous solid solution series with pickingerite and chemical analysis shows that the jarosite contains 6% Mg(2+). Halotrichite is characterised by four infrared bands at 3569.5, 3485.7, 3371.4 and 3239.0 cm(-1). Using Libowitsky type relationships, hydrogen bond distances of 3.08, 2.876, 2.780 and 2.718 Angstrom were determined. Two intense Raman bands are observed at 987.7 and 984.4 cm(-1) and are assigned to the nu(1) symmetric stretching vibrations of the sulphate bonded to the Fe(2+) and the water units in the structure. Three sulphate bands are observed at 77K at 1000.0, 991.3 and 985.0 cm(-1) suggesting further differentiation of the sulphate units. Raman spectrum of the nu(2) and nu(4) region of halotrichite at 298 K shows two bands at 445.1 and 466.9 cm(-1), and 624.2 and 605.5 cm(-1), respectively, confirming the reduction of symmetry of the sulphate in halotrichite.
authors.affiliation: Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Qld 4001, Australia.
authors.forename: Ray L
authors.initials: RL
authors.lastname: Frost
authors.forename: Matt L
authors.initials: ML
authors.lastname: Weier
authors.forename: J Theo
authors.initials: JT
authors.lastname: Kloprogge
authors.forename: Fernando
authors.initials: F
authors.lastname: Rull
authors.forename: Jesus
authors.initials: J
authors.lastname: Martinez-Frias
mesh_terms: D000534:Alum Compounds / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D013030:Spain; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013431:Sulfates / Q000737:chemistry*
chemical_list: D000534:Alum Compounds; D005296:Ferrous Compounds; D013431:Sulfates; C510105:halotrichite