Raman Spectroscopic and SEM Analysis of Sodium-Zippeite

Raman at 298 and 77 K and infrared spectra of two samples of sodium-zippeite were studied and interpreted. U-O bond lengths in uranyl were calculated and compared with those inferred from the X-ray single crystal structure data of a synthetic sodium-zippeite analog. Hydrogen-bonding network in the studied samples is discussed. O-H…O bond lengths were calculated and compared with those predicted from the X-ray single crystal structure analysis

Raman Spectroscopic Analysis of Geological and Biogeological Specimens of Relevance to the ExoMars Mission

H.G.M.E., I.H., and R.I. acknowledge the support of the STFC Research Council in the UK ExoMars programme. J.J. and P.V. acknowledge the support of the Grant Agency of the Czech Republic (210/10/0467) and of the Ministry of Education of the Czech Republic (MSM0021620855).Peer reviewedPublisher PD

Synthesis and vibrational spectroscopic characterisation of synthetic hydrozincite and smithsonite

Hydrozincite and smithsonite were synthesised by controlling the partial pressure of CO2 . Previous crystallographic studies concluded that the structure of hydrozincite was a simple one. However both Raman and infrared spectroscopy show that this conclusion is questionable. Multiple bands are observed in both the Raman and infrared spectra in the (CO3)2-antisymmetric stretching and bending regions of hydrozincite showing that the symmetry of the carbonate anion is reduced and in all probability the carbonate anions are not equivalent in the hydrozincite structure. Multiple OH stretching vibrations centred in both the Raman and infrared spectra show that the OH units in the hydrozincite structure are non-equivalent. The Raman spectrum of synthetic smithsonite is a simple spectrum characteristic of carbonate with Raman bands observed at 1408, 1092 and 730 cm-1. The symmetry of the carbonate anion in hydrozincite is C2v or Cs. This symmetry reduction results in multiple bands in both the symmetric stretching and bending regions. The intense band of hydrozincite at 1062 cm-1 is assigned to the ν1 (CO3)2- symmetric stretching mode. Three Raman bands assigned to the ν3 (CO3)2- antisymmetric stretching modes are observed for hydrozincite at 1545, 1532 and 1380 cm-1. Multiple infrared or Raman bands are observed in 800 to 850 cm-1 and 720 to 750 cm-1 regions and are attributed to ν2 and ν4 bending modes confirming the reduction of the carbonate anion symmetry in the hydrozincite structure. A Raman band for hydrozincite at 980 cm-1 is attributed to the δ OH deformation mode

Synthesis of microporous silica nanoparticles to study water phase transitions by vibrational spectroscopy

Silica can take many forms, and its interaction with water can change dramatically at the interface. Silica based systems offer a rich tapestry to probe the confinement of water as size and volume can be controlled by various templating strategies and synthetic procedures. To this end, microporous silica nanoparticles have been developed by a reverse microemulsion method utilizing zinc nanoclusters encapsulated in hydroxyl-terminated polyamidoamine (PAMAM-OH) dendrimers as a soft template. These nanoparticles were made tunable within the outer diameter range of 20-50 nm with a core mesopore of 2-15 nm. Synthesized nanoparticles were used to study the effects of surface area and microporous volumes on the vibrational spectroscopy of water. These spectra reveal contributions from bulk interfacial/interparticle water, ice-like surface water, liquid-like water, and hydrated silica surfaces suggesting that microporous silica nanoparticles allow a way to probe silica water interactions at the molecular scale

Raman–Mo¨ssbauer–XRD studies of selected samples from ‘‘Los Azulejos” outcrop: A possible analogue for assessing the alteration processes on Mars

The outcrop of ‘‘Los Azulejos” is visible at the interior of the Can˜adas Caldera in Tenerife Island (Spain). It exhibits a great variety of alteration processes that could be considered as terrestrial analogue for several geological processes on Mars. This outcrop is particularly interesting due to the content of clays, zeolite, iron oxides, and sulfates corresponding to a hydrothermal alteration catalogued as ‘‘Azulejos” type alteration. A detailed analysis by portable and laboratory Raman systems as well as other different techniques such as X-ray diffraction (XRD) and Mo¨ssbauer spectroscopy has been carried out (using twin-instruments from Martian lander missions: Mo¨ssbauer spectrometer MIMOS-II from the NASA-MER mission of 2001 and the XRD diffractometer from the NASA-MSL Curiosity mission of 2012). The mineral identification presents the following mineral species: magnetite, goethite, hematite, anatase, rutile, quartz, gregoryite, sulfate (thenardite and hexahydrite), diopside, feldspar, analcime, kaolinite and muscovite. Moreover, the in-situ Raman and Micro- Raman measurements have been performed in order to compare the capabilities of the portable system specially focused for the next ESA Exo-Mars mission. The mineral detection confirms the sub-aerial alteration on the surface and the hydrothermal processes by the volcanic fluid circulations in the fresh part. Therefore, the secondary more abundant mineralization acts as the color agent of the rocks. Thus, the zeolite–illite group is the responsible for the bluish coloration, as well as the feldspars and carbonates for the whitish and the iron oxide for the redish parts. The XRD system was capable to detect a minor proportion of pyroxene, which is not visible by Raman and Mo¨ssbauer spectroscopy due to the ‘‘Azulejos” alteration of the parent material on the outcrop. On the other hand, Mo¨ ssbauer spectroscopy was capable of detecting different types of iron-oxides (Fe3+/2+-oxide phases). These analyses emphasize the strength of the different techniques and the working synergy of the three different techniques together for planetary space missions

Standoff Ultra-Compact Micro-Raman Sensor for Planetary Surface Explorations

We report the development of an innovative standoff ultracompact micro-Raman instrument that would solve some of the limitations of traditional micro-Raman systems to provide a superior instrument for future NASA missions. This active remote sensor system, based on a 532 nm laser and a miniature spectrometer, is capable of inspection and identification of minerals, organics, and biogenic materials within several centimeters (220 cm) at a high 10 m resolution. The sensor system is based on inelastic (Raman) light scattering and laser-induced fluorescence. We report on micro-Raman spectroscopy development and demonstration of the standoff Raman measurements by acquiring Raman spectra in daylight at a 10 cm target distance with a small line-shaped laser spot size of 17.3 m (width) by 5 mm (height)