Kinematics of α-emitting dilute colloidal dispersions

Colloidal dispersions and their rheology are well-understood and have been used for many scientific applications. Kinematics of dilute or dense colloidal dispersions, which play a critical role in their application deployment potential, are modeled using Stokesian dynamics and the Langevin equation. These models are applied for predicting rheological behavior under an external field or for self-propelled colloids. Explored here is a new class of colloidal dispersions with α-emitting radioactive isotopes as constituents of colloidal particles. Emission of a heavy charged nucleus (⁴He²⁺) can impart substantial momentum to the nano- or micro-scale colloidal particle that is the source of the radioactive emission. For a certain size and composition of α-emitting colloidal particles, kinematics are largely governed by the impulse generated from radioactive discharge. Other forces, such as Brownian forces or those due to an external field, such as gravity, have reduced importance. In light of this, a new force term with random and fixed components accounting for radioactive emission impulse has been derived analytically and verified via numerical simulations.