The study of Raman enhancement efficiency as function of nanoparticle size and shape

This work is focused on studying the dependence of Raman enhancement of p-aminothiophenol molecules adsorbed on self-assembled gold monolayers as function of nanoparticle size and shape. Gold nanoparticles of different sizes (ranging from 18 nm to 100 nm) and shapes (round and ellipsoidal) were synthesized by reduction of tetrachloroauric acid (HAuCl4) in aqueous medium by varying the ratio between the reducing agent (trisodium citrate) and gold salt, and were immobilized on functionalized glass substrates. The optical properties of the prepared samples were investigated by absorbance measurements taken before and after the adsorption of the molecule. We found that the Raman enhancement of probe molecules measured under 633 nm laser line strongly depends on the sizes of self-assembled gold nanoparticles.