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Spectroscopic measurements have been made of two suites of olivine minerals synthesized under slightly different conditions in 5-10 mol% increments across the solid solution from forsterite to fayalite. Here, we present Mössbauer results for the entire Fe-Mg olivine suite, as well as the results for only the fayalite end-member as an introduction to our team’s other diverse spectral-analysis techniques and data that will be presented in forthcoming papers. Experimental methods used to synthesize both suites of samples are discussed here in detail, along with specifics of the analytical techniques used to study them. Electron microprobe data and Mössbauer spectra acquired at 293 K across the solid solution are presented first to characterize and address the presence of impurities in the broad suite of samples that may affect other spectroscopic methods. We then focus specifically on the fayalite end-member to illustrate its properties using multiple techniques. Fayalite is an especially important phase for different types of spectroscopy because, by definition, it contains an equal distribution of Fe2+cations between the M1 and M2 octahedral sites. Thus, features associated with each of the two sites must represent equal numbers of Fe2+cations, removing uncertainties associated with assumptions about order/disorder of Fe2+and other cations. Mössbauer, Raman, thermal emission, attenuated total reflectance (ATR), specular reflectance, and visible to mid-infrared total reflectance studies are presented for fayalite. These include calculation of mid-infrared optical constants (n and k) and fundamental Mössbauer parameters: intrinsic isomer shift (δI), Mössbauer temperature (θM), and recoil-free fraction (f). Data from the different techniques are described and related, demonstrating the importance of multi-wavelength data to provide a complete characterization and understanding of the spectroscopic features in fayalite.

Abstract—We report combined micro‐infrared, micro‐Raman, and field emission scanning electron microscope (FESEM) analyses of particles collected by the Stardust spacecraft during its flyby of comet 81P/Wild 2 on 2 January 2004 and successfully returned back to Earth on 15 January 2006. We present mid‐infrared (IR) spectra of six of these particles. The CH2/CH3ratios inferred from the infrared data are greater than those seen in organics in the diffuse interstellar medium, possibly indicating the presence of longer or less branched aliphatic chains. The micro‐Raman data offer insights into the state of the order of the carbonaceous component present in the particles. Raman parameters for most of the particles span a similar range to that observed in interplanetary dust particles (IDPs) and the most primitive meteorites. Both the IR and Raman data imply the presence of a very labile carbonaceous component. Hydrated silicates may be present in two particles of Track 35, one of which may also contain carbonates, but further investigations with other techniques need to be performed to confirm these findings. In some cases, the analyses are difficult to interpret because of the presence of compressed aerogel mixed with the grains.

Acidic proteins from many biogenic minerals are implicated in directing the formation of crystal polymorphs and morphologies. We characterize the first extremely acidic proteins purified from biomineralized aragonite. These abalone nacre proteins are two variants of 8.7 and 7.8 kDa designated AP8 (for aragonite proteins of approximately 8 kDa). The AP8 proteins have compositions dominated by Asx (~35 mol %) and Gly (~40 mol %) residues, suggesting that their structures have high Ca²⁺-binding capacity and backbone flexibility. The growth of asymmetrically rounded CaCO3 crystals in the presence of AP8 reveals that both proteins preferentially interact with specific locations on the crystal surface. In contrast, CaCO3 crystals grown with nacre proteins depleted of AP8 retain the morphology of unmodified calcite rhombohedra. Our observations thus identify sites of protein−mineral interaction and provide evidence to support the long-standing theory that acidic proteins are more effective crystal-modulators than other proteins from the same biomineralized material.

Sioct-O-Sitet-O Infrared reflectance, thin-film absorbance, and polarized Raman spectra were acquired from -100 to -4000 cm-1from polycrystalline garnets along the pyrope (Py = Mg3Al2Si3O12)-majorite [Mj = Mg3(MgSi)Si3O12] join. We measured Py100, Mj39, Mj45, Mj80, and natural single-crystal, nearly endmember pyrope. Consistency is obtained between measured absorption spectra and absorption coefficients calculated through Kramers-Kronig analysis of reflectivity (R) data, if R-values are scaled to account for losses through scattering. The widths of the lattice modes double from each end-member toward the middle of the binary, whereas frequencies are nearly independent of composition. Strong polarization of Raman peaks of all our samples except pyrope shows that the space group is reduced from cubic, even for the Al-rich majorites. The largest number of IR or Raman peaks is observed for Mj80. The number of peaks for Al-rich majorites lies between those seen for cubic pyrope and I41/a majorite. The behavior of symmetry-breaking modes supports the I41/acd space group, which was inferred from X-ray data for Mj contents near 30 to 45% (Nakatsuka et al. 1999a). Also, the internal mode types that are expected for isolated SiO4tetrahedra in any garnet-like structure do not fully describe the patterns of peaks seen for some intermediate compositions along the Py-Mj join. The appearance of Sioct-O-Sitetbending modes in the available spectral data for Mj contents near 30-40 and 80-90%, but not near 45-50%, is attributed to two-mode behavior. Specifically, disruption of the structural chain -Sioct-O-Sitet-O-Sioct-O-Sitet- in Si-rich majorites by units such as alters the electrostatic balance so that the internal modes are not entirely described by motions of isolated SiO4tetrahedra. Short chains are formed at both high and low Al contents, promoting coupling of Si octahedral and tetrahedral vibrations. Near Mj50, each tetrahedron is linked (on average) to four octahedra containing two Al-, one Si-, and one Mg, and the Sioct-O-Sitetbending modes disappear. Order-disorder in majorite garnets is characterized not only by increased peak widths, but also by the presence of modes due to the bridging O atoms, whereas splittings and the appearance of new peaks indicate the space group for non-cubic garnets.

Analytical data of inorganic and organic components from aerosol immission samples contain complex information about the sources contributing to the particulate air pollution. To extract this information “receptor models” have been developed during the last years. The successful use of such models is highly depending from the quality of the available data set. Thus, a careful planning of the experiment is required. Of major importance is the choice of the analyzed elements or components, the size classified sampling, the sampling interval and the choice of the sampling place. Information about source profiles of the analyzed components and considering the meteorological situation during sampling can lead to further valuable input data for certain types of “receptor models”. Finally, the requirements on the quality of the analytical data have to be defined.