Raman spectroscopy goes to Mars

摘要

Introduction Raman spectroscopy is well recognised as a powerful tool for the chemical and structural identification of materials in the solid, liquid or gas state. Its analytical capabilities, both macroand micro-, without the need to perturb a sample, have made this technique unique for many applications where the materials are scarce or very valuable and rare. As a consequence of these capabilities a great expansion in applications has been seen in the last 20 years across many fields ranging, inter alia, from chemistry to mineralogy and geology, art and archaeology, forensic sciences, polymers and biomaterials. In spite of this expansion and the capabilities of Raman spectroscopy, it has been, and to a great extent still is, considered a laboratory technique. Nevertheless, in recent years several systems have been specifically developed for field applications. These systems have profited from recent technical advances in laser sources, optical elements and spectrometers and detectors, which have led to the possibility of developing robust, compact and miniaturised spectrometers, which have many of the spectral capabilities of laboratorybased systems. These developments also paved the way for the potential use of Raman spectroscopy in planetary exploration as part of rover or lander instrumentation, in particular for the exploration of Mars. At present, Raman spectroscopy, separately or in combination with LIBS (laser induced breakdown spectroscopy) or fluorescence, is considered as a fundamental, next-generation instrument for the characterisation of mineralogical and organic material during exploration of Mars. While instrumentation for robotic missions is probably the most important consideration for Mars exploration, it is also important to note that Raman applications adding to the knowledge of Mars also cover other important aspects, such as the study of Martian meteorites and potential terrestrial Mars analogues. In the context of this general framework, we will, in this article, discuss some recent developments and applications of Raman spectroscopy for planetary exploration with particular interest on Mars.