Abstract: A process for the deposition of a thin film of a desired material on a surface comprising: (i) providing a continuous stream of amorphous solid particles of desired material suspended in at least one carrier gas, the solid particles having a volume-weighted mean particle diameter of less than 500 nm, at an average stream temperature below the glass transition temperature of the solid particles of desired material, (ii) passing the stream provided in (i) into a heating zone, and heating the stream in the heating zone to elevate the average stream temperature to above the glass transition temperature of the solid particles of desired material, wherein no substantial chemical transformation of the desired material occurs due to heating of the desired material, (iii) exhausting the heated stream from the heating zone through at least one distributing passage, at a rate substantially equal to its rate of addition to the heating zone in step (ii), wherein the carrier gas does not undergo a thermodynamic phase chang