Compared with a nanoscale length of a few atomic diameters, even microscopic lengths are very large.  It is known that at larger lengths, colliding drops always coalesce when their diameters and dimensions are small enough.  However, we have found that two nanoscale jets flowing head on against one another always recoil following collision, but after a time lag during which the jets absorb the impact of the collision.  The duration between collision and recoil is a function of the nanojet impact velocity and the nature of interteractions between its molecules.  During recoil, evaporation occurs, which promotes mixing. Thereafter, mixing occurs through diffusion.  Listeners are referred to a paper by S. Murad and I. K. Puri that appeared in Volume 7 of the scientific journal Nano Letters (pp. 707-712, 2007).