title: Electron paramagnetic resonance, optical absorption and IR spectroscopic studies of the sulphate mineral apjohnite.
abstract: Apjohnite, a naturally occurring Mn-bearing pseudo-alum from Terlano, Bolzano, Italy, has been characterized by EPR, optical, IR and Raman spectroscopy. The optical spectrum exhibits a number of electronic bands around 400 nm due to Mn(II) ion in apjohnite. From EPR studies, the parameters derived, g=2.0 and A=8.82 mT, confirm MnO(H(2)O)(5) distorted octahedra. The presence of iron impurity in the mineral is reflected by a broad band centered around 8400 cm(-1) in the NIR spectrum. A complex band profile appears strongly both in IR and Raman spectra with four component bands around 1100 cm(-1) due to the reduction of symmetry for sulphate ion in the mineral. A strong pair of IR bands at 1681 and 1619 cm(-1) with variable intensity is a proof for the presence of water in two states in the structure of apjohnite.
authors.affiliation: Department of Physics, S.V.D. College, Kadapa 516003, India.
authors.forename: S
authors.initials: S
authors.lastname: Lakshmi Reddy
authors.forename: G
authors.initials: G
authors.lastname: Siva Reddy
authors.forename: D L
authors.initials: DL
authors.lastname: Wain
authors.forename: W N
authors.initials: WN
authors.lastname: Martens
authors.forename: B
authors.initials: B
authors.lastname: Jagannatha Reddy
authors.forename: R L
authors.initials: RL
authors.lastname: Frost
mesh_terms: D000042:Absorption; D000534:Alum Compounds / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D017895:Manganese Compounds / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D019265:Spectroscopy, Near-Infrared; D013431:Sulfates / Q000737:chemistry*
chemical_list: D000534:Alum Compounds; D017895:Manganese Compounds; D008903:Minerals; D013431:Sulfates; C518761:apjohnite