Nano-infrared spectroscopy of extraterrestrial samples

Near-field spectroscopy is a technique uniquely suited to non-destructive chemical identification of the sub-micron regions and chemical phases found in heterogeneous natural samples, such as those returned to Earth from the dust cloud surrounding Comet 81P/Wild 2 by NASA’s Stardust Discovery Mission spacecraft after its 2004 flyby. These returned extraterrestrial samples provide tangible access to the composition of matter in the early solar system, as well as glimpses of organic materials and rare pre-solar stardust grains. While the spatially-resolved study of these materials traditionally has relied on the sub-diffraction resolving power of electron- and X-ray microscopies, these techniques are invariably destructive to valuable samples, to the preclusion of follow-up investigations. In contrast, near-field infrared spectroscopy combines the non-destructive imaging capabilities of atomic force microscopy (AFM) and near-field microscopy with Fourier-transform infrared spectroscopy (FTIR), enabling spectroscopic identification of materials and mineral structures at the scale of tens of nanometers.

Nanoscale infrared spectroscopy as a non-destructive probe of extraterrestrial samples
Nature Communications 5, 5445 (2014). Ref. [200]

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picture21Advances in the spatial resolution of modern analytical techniques have tremendously augmented the scientific insight gained from the analysis of natural samples. Infrared spectroscopy remains an invaluable contactless probe of chemical structure, details of which offer clues to the formation history of minerals. Here we report on the successful implementation of infrared near-field imaging, spectroscopy and analysis techniques capable of sub-micron scale mineral identification within natural samples, including a chondrule from the Murchison meteorite and a cometary dust grain (Iris) from NASA’s Stardust mission.