Micro-Raman spectroscopic study of extremely large atmospheric ice conglomerations (megacryometeors)

Abstract

For the first time, micro-Raman spectroscopy has been applied to the structural study of four megacryometeors (extremely large atmospheric ice conglomerations that fall in general under blue-sky atmospheric conditions) that fell in Spain. The Raman spectra taken on the megacryometeor cores have been compared with those obtained from an in situ and online study performed on the crystallization process of water in the laboratory. A detailed comparison of the band profiles obtained made it possible to place the formation of the megacryometeors within a particular range of temperatures (−10 to −20• C), which in turn can be related with the altitude of formation in the atmosphere. These results have also been compared with isotope concentrations (d 18 O and dD) previously obtained in these cores. The two sets of results show a close correlation.

Biomarkers and their Raman spectroscopic signatures: a spectral challenge for analytical astrobiology

“…In a recent special issue of the Philosophical Transactions of the Royal Society, in a year that celebrated its 350th anniversary as the longest running scientific journal, several articles highlighted the role of Raman spectroscopy in the characterization of biosignatures of extremophilic colonization of geological substrates in a range of stressed terrestrial environments [25,30,[36][37][38][39][40][41][42][43][44][45]; these articles in the same issue which address the detection of geological and biogeological spectral markers that are relevant to space missions give a very good appreciation of the spectroscopic requirements that will be essential for the construction of a relevant spectral database [46] for the ExoMars and forthcoming space missions which have a Raman spectrometer aboard their rover vehicles. Some selected examples of the data which can be provided by the Raman spectroscopic interrogation of terrestrial Mars analogue sites will be highlighted.…”

Analysis of Arctic ices by Remote Raman Spectroscopy

“…The structural information obtained from Raman spectra is quite useful and can be related with temperature and pressure effects on ice [20,21]. The Raman spectrum of ice is well known and consist basically on the three internal vibrations of the water molecules (symmetric v 1 (A 1 ) and antisymmetric v 3 (B 2 ) OH stretching modes, and HOH bending v 2 (A 1 ) mode) and the external modes, mainly water translations and librations.…”

“…Nevertheless a particular characteristic of the vibrational spectrum of liquid water and ice is the strong intermolecular couplings between neighboring molecules as a consequence of the networking of hydrogen bonds. In consequence the in-phase and out-phase couplings and other intermolecular waterinteractions have to be considered for the correct interpretation of the spectra experimentally obtained [16][17][18][19][20][21].…”

Advanced Technique for In Situ Raman Spectroscopy Monitoring of the Freezing-Induced Loading Process

“…At present, there are several methods for the phase-transition determination, such as optical microscopy, calorimetric method, high-resolution X-ray absorption radiography and tomography, , dielectric spectroscopy, , optoacoustic spectroscopy (photoacoustic spectroscopy), − and Raman spectroscopy. − Microscopy makes it possible to study in detail the shape of the crystallization front and the zone of concentration overcooling and determine the thickness of the formed ice lamellas. You et al presented a method based on microscopy, making it possible to determine with reasonable accuracy the crystallization front velocity and the constitutional undercooling zone.…”