https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5788557
*Authors: *Joshin Kumar, Gwan-Yeong Jung, Taveen S. Kapoor, Rohan Mishra, Rajan Chakrabarty *22 November 2025* *Abstract* Stratospheric aerosol injection (SAI) using diamond dust has been proposed as a solar radiation management technique to mitigate global warming by scattering incoming solar radiation, offering advantages over sulfur-based aerosols such as reduced ozone depletion and acid rain risks. However, detonation synthesis—the most economical method for large-scale nanodiamond production—inevitably introduces sp2-hybridized carbonaceous impurities, often forming shells around diamond cores, which may enhance shortwave absorption and undermine SRM efficacy. This study employs density functional theory and ab-initio molecular dynamics to model these impurities across hydrogen-to-carbon (H/C) ratios from 0.0 to 1.0, revealing a continuum of optical properties where decreasing sp2 content reduces the imaginary refractive index (k). Particle-scale core-shell Mie scattering simulations at 550 nm for diamond cores of 300 nm diameter with carbonaceous impurity shells (1.95 + ki refractive index, shell thickness of ~0.1–10 nm corresponding to 0.1–10% impurity mass fraction) show that these impurities elevate the effective mass absorption coefficient to up to ~1 m2/g—nearly 15% that of black carbon (~7.5 m2/g)—and decrease single-scattering albedo by up to 25% relative to pure diamond. These absorption enhancements, driven by the k and impurity mass fraction of the shell, could shift diamond dust's radiative forcing toward warming. Our findings highlight the critical need to revisit diamond’s efficacy as an SAI candidate material. *Source: SSRN* -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/geoengineering/CAHJsh99g%3DUpGvrV-W-P_JiizaMPfb6mE%3D4kORcV3H1wXcmyYVA%40mail.gmail.com.
