Organic matter in Ryugu vs. carbonaceous chondrites: IR spectroscopic perspectives

Abstract

As a part of the organic macromolecule subteam, infrared absorption spectra from the intact Ryugu particles and extracted insoluble organic matter (IOM) were obtained using Fourier transform infrared (FTIR) microspectroscopy, to understand the nature of organic matter in Ryugu. Both in the case of intact particles and extracted IOM, the IR absorption spectra of chamber A and chamber C were almost identical, but some local heterogeneity exists. The Ryugu IOM had the highest CH2/CH3 with the highest aliphatic CH/aromatic C=C ratios compared to unheated chondritic IOM. We also observed possible N-H features in the Ryugu IOM. Such characteristics of Ryugu organic matter might indicate freshness of the Ryugu particles, which is not preserved in carbonaceous chondrites.