Diiodomethane is primarily used in the field of organic synthesis as a reagent for various chemical reactions. It is often employed in the preparation of iodinated compounds, which are valuable intermediates in the synthesis of pharmaceuticals and agrochemicals. In analytical chemistry, diiodomethane is utilized as a heavy liquid for density gradient separations, particularly in the purification and analysis of minerals and polymers. Additionally, it serves as a contrast agent in X-ray imaging due to its high density and iodine content, enhancing the visibility of certain structures. In materials science, diiodomethane is used to measure the surface energy of solids through contact angle measurements, aiding in the characterization of surface properties. Its applications also extend to the synthesis of organometallic compounds and as a solvent in specific chemical processes.