title: Nanoscale infrared spectroscopy as a non-destructive probe of extraterrestrial samples.
abstract: Advances in the spatial resolution of modern analytical techniques have tremendously augmented the scientific insight gained from the analysis of natural samples. Yet, while techniques for the elemental and structural characterization of samples have achieved sub-nanometre spatial resolution, infrared spectral mapping of geochemical samples at vibrational 'fingerprint' wavelengths has remained restricted to spatial scales >10 μm. Nevertheless, 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. Complementary to scanning electron microscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy probes, this work evidences a similarity between chondritic and cometary materials, and inaugurates a new era of infrared nano-spectroscopy applied to small and invaluable extraterrestrial samples.
authors.affiliation: 1] Department of Physics, California State University, San Marcos, San Marcos, California 92096-0001, USA [2] Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Dominguez
authors.affiliation: Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Mcleod
authors.affiliation: Space Sciences Laboratory, University of California, Berkeley, Berkeley, California 94720, USA.
authors.forename: Zack
authors.initials: Z
authors.lastname: Gainsforth
authors.affiliation: Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: P
authors.initials: P
authors.lastname: Kelly
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Hans A
authors.initials: HA
authors.lastname: Bechtel
authors.affiliation: Ludwig-Maximilians-Universität and Center for Nanoscience, 80539 München, Germany.
authors.forename: Fritz
authors.initials: F
authors.lastname: Keilmann
authors.affiliation: Space Sciences Laboratory, University of California, Berkeley, Berkeley, California 94720, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Westphal
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Thiemens
authors.affiliation: Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: D N
authors.initials: DN
authors.lastname: Basov