  Nanocrystalline samples of pristine capped and uncapped zinc sulphide were
synthesized via the sol-gel technique. The nanocrystallinity of the samples
were confirmed by the X-ray diffraction technique, where size of the particle
size decreases with the increasing of mol. concentration (x = 0.00, 0.02, 0.03,
0.04 Mol). of capping agent sodium dodecyle sulphate. The obtained crystallite
sizes were found to be in the range 4.6 nm to 2.7 nm respectively. The optical
band gaps of the samples were estimated by using ultra-violet visible
spectroscopic techniques and the band gap values were in the range 3.8 eV to
4.4 eV. All the samples showed quantum confinement behavior compared to bulk
sample. Fluorescence (FL) spectra showed three emission peaks at the emission
wavelengths around 434 nm, 520 nm, 545 nm, 628 nm, and 694 nm. The FL
intensities were proportional to the concentration of capping agent.
