The general goal of this project is the experimental validation of a new moderation concept to produce very cold neutron (VCNs) with large potential impact for condensed-matter and particle-physics research. The perspective is an improvement of currently available intensities, by up to two orders of magnitude, for neutrons with wavelength larger than 2 nm, covering the whole energy range down to ultra-cold neutrons. Densely packed O2 as a host in fully deuterated O2-clathrate hydrate [2] has been identified as a candidate for a highly promising practical moderator material. The purpose of this proposal is to perform absolute measurements of the relevant scattering cross sections in order to enable realistic calculations of moderation efficiencies.