Thiophenol-capped ZnS quantum dots

Free-standing, stable, single-sized, and highly pure ZnS nanosize particles or quantum dots are synthesized using a chemical route. The dimension of the quantum dots as estimated from x-ray diffraction was about 7 and 15 Å. The optical band gap for these particles was 5.2 and 4.8 eV, respectively, as compared with the bulk energy gap of 3.8 eV. These results are compared with the effective mass approximation. The observations indicate that only particular-sized stable particles can be synthesized which should have minimum energy configuration. X-ray photoelectron spectroscopy was utilized for examining stoichiometry and purity of the sample.