Influence of various capping agents on optical properties and stability of MnS nanoparticles

Two thiols (L-cysteine and thioglycolic acid) as well as citrate-anion were employed as coordinating reagents to control the MnS nanoparticles nucleation and growth at various pH in aqueous media. The obtained colloids were characterized by means of UV–visible spectroscopy and atomic force microscopy. Mass fraction of elements was estimated by Energy Dispersive X– ray. Effect of the nanoparticles forming ions (Mn2+ and S2-) molar ratio as well as the capping agents nature and content (the ligands coordination number c. n. = 2; 4 and 6) on UV–vis absorbance spectra was studied. It was determined that Mn2+– ions amount and the coordination number of the stabilizers needed for effective capping of the MnS nanoparticles are close in the three studied cases. Possibility of Mn(OH)2 formation as an additional product of S2-- and Mn2+– ions interaction in aqueous medium is discussed.