powder (S, 99.99%), silver chloride
(AgCl, 99.9%), selenium powder (Se, 99.9%), and tri-n-octylphosphine
(TOP, 97%) were obtained from Strem Chemicals. Silver nitrate (AgNO3, 99%), gold(III) chloride trihydrate (HAuCl4·3H2O, ≥99.9%), oleylamine (OLAm, 70%), tri-n-octylphosphine
oxide (TOPO, 99%), sodium borohydride (NaBH4, 98%), tetrahydrofuran
(THF, 99%), octadecene (ODE, 90%), and toluene (99.9%), 11-mercaptoundecanoic
acid (MUA, 95%), and sodium citrate tribasic dihydrate were purchased
from Sigma-Aldrich. Ethanol (EtOH, 96%) and acetone (99.5%) were obtained
from Panreac.