Context. The reflectance spectra of some main-belt asteroids contain a 3-µm band, which is explained by the presence of water or hydroxyl groups in minerals. Recent observations of 24-Themis have been found to display evidence of water ice. Aims. We synthesize iron oxy-hydroxide materials and in the laboratory measure their near-infrared spectra under dry conditions to compare with asteroid observations. Methods. The syntheses are performed using either the well-established titration method or a non-conventional hydrothermal method. Bi-directional near-infrared reflectance spectra are obtained using the spectrogonio radiometer available at LPG/IPAG. Spectra are measured in a vacuum to avoid contamination by adsorbed water. Results. The reflectance spectra that we measure for synthesized goethite are consistent with published transmission spectra. The 3-µm band in goethite has a minimum around 3.10 µm, similar to observations of 24-Themis. Its overall shape matches well Themis's 3-µm band; goethite-like oxy-hydroxydes are a viable alternative way of explaining 24-Themis near-IR spectra
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.