Determination of Martian meteorite lithologies and mineralogies using vibrational spectroscopy

1997 ◽  
Vol 102 (E11) ◽  
pp. 25593-25603 ◽  
Author(s):  
Victoria E. Hamilton ◽  
Philip R. Christensen ◽  
Harry Y. McSween
Keyword(s):  
Vibrational Spectroscopy ◽  
Martian Meteorite

scholarly journals EXAFS Determination of Clay Minerals in Martian Meteorite Allan Hills 84001 and Its Implication for the Noachian Aqueous Environment

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 176
Author(s):  
Ryoichi Nakada ◽  
Gaku Tanabe ◽  
Iori Kajitani ◽  
Tomohiro Usui ◽  
Masashi Shidare ◽  
...  
Keyword(s):  
Silica Glass ◽  
Large Body ◽  
Aqueous Environment ◽  
Martian Surface ◽  
Exafs Analysis ◽  
Martian Meteorite ◽  
Fe Species ◽  
Allan Hills 84001 ◽  
X Ray Absorption

The aqueous environment of ancient Mars is of significant interest because of evidence suggesting the presence of a large body of liquid water on the surface at ~4 Ga, which differs significantly from the modern dry and oxic Martian environment. In this study, we examined the Fe-bearing minerals in the 4 Ga Martian meteorite, Alan Hills (ALH) 84001, to reveal the ancient aqueous environment present during the formation of this meteorite. Extended X-ray absorption fine structure (EXAFS) analysis was conducted to determine the Fe species in ALH carbonate and silica glass with a high spatial resolution (~1–2 μm). The μ-EXAFS analysis of ALH carbonate showed that the Fe species in the carbonate were dominated by a magnesite-siderite solid solution. Our analysis suggests the presence of smectite group clay in the carbonate, which is consistent with the results of previous thermochemical modeling. We also found serpentine in the silica glass, indicating the decrease of water after the formation of carbonate, at least locally. The possible allochthonous origin of the hematite in the carbonate suggests a patchy redox environment on the ancient Martian surface.

Determination of G*G.cntdot.C triple-helix structure by molecular modeling and vibrational spectroscopy

1993 ◽  
Vol 115 (10) ◽  
pp. 4264-4270 ◽  
Author(s):  
Mohammed Ouali ◽  
Richard Letellier ◽  
Jian Sheng Sun ◽  
Alain Akhebat ◽  
Frederic Adnet ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Vibrational Spectroscopy ◽  
Triple Helix ◽  
Helix Structure

scholarly journals Facet-specific interaction between methanol and TiO2 probed by sum-frequency vibrational spectroscopy

2018 ◽  
Vol 115 (17) ◽  
pp. E3888-E3894 ◽  
Author(s):  
Deheng Yang ◽  
Yadong Li ◽  
Xinyi Liu ◽  
Yue Cao ◽  
Yi Gao ◽  
...  
Keyword(s):  
Vibrational Spectroscopy ◽  
Molecular Form ◽  
Specific Interaction ◽  
Fermi Resonance ◽  
Free Energies ◽  
Sum Frequency ◽  
Resonance Coupling ◽  
Bending Modes ◽  
Titanium Dioxides

The facet-specific interaction between molecules and crystalline catalysts, such as titanium dioxides (TiO2), has attracted much attention due to possible facet-dependent reactivity. Using surface-sensitive sum-frequency vibrational spectroscopy, we have studied how methanol interacts with different common facets of crystalline TiO2, including rutile(110), (001), (100), and anatase(101), under ambient temperature and pressure. We found that methanol adsorbs predominantly in the molecular form on all of the four surfaces, while spontaneous dissociation into methoxy occurs preferentially when these surfaces become defective. Extraction of Fermi resonance coupling between stretch and bending modes of the methyl group in analyzing adsorbed methanol spectra allows determination of the methanol adsorption isotherm. The isotherms obtained for the four surfaces are nearly the same, yielding two adsorbed Gibbs free energies associated with two different adsorption configurations singled out by ab initio calculations. They are (i) ∼−20 kJ/mol for methanol with its oxygen attached to a low-coordinated surface titanium, and (ii) ∼−5 kJ/mol for methanol hydrogen-bonded to a surface oxygen and a neighboring methanol molecule. Despite similar adsorption energetics, the Fermi resonance coupling strength for adsorbed methanol appears to depend sensitively on the surface facet and coverage.

Determination of the CO3− bond strength via the resonant two-photon photodissociation threshold: Electronic and vibrational spectroscopy of CO3−∙Arn

2006 ◽  
Vol 124 (17) ◽  
pp. 174302 ◽  
Author(s):  
Joseph C. Bopp ◽  
Eric G. Diken ◽  
Jeffrey M. Headrick ◽  
Joseph R. Roscioli ◽  
Mark A. Johnson ◽  
...  
Keyword(s):  
Bond Strength ◽  
Vibrational Spectroscopy ◽  
Two Photon
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