Abstract:
Cadmium Sulphide is a group II–VI semiconductor nanoparticle and it has unique sizedependent
properties. In this study, size dependent Cadmium sulphide nanoparticle was
prepared by chemical precipitation with different molar ratios ((16:1), (8:1), (1:1) and (1:8)) of
cadmium acetate and sodium sulphide. The synthesized nanoparticle was characterized with UVvisible
spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and Scanning
electron microscope. The structure of nanoparticle was crystal with a particular size of 3.35 nm.
Owing to quantum confinement effect the nanocrystals show a unique blend of molecular and
solid properties: discrete energy levels with large polarizability that could respond to solvent
environments. Furthermore, we have presented the size dependent solvatochromism of Cadmium
Sulfide nanoparticles using steady state fluorescence and absorption spectroscopy. The
absorption and fluorescence emission spectrum of Cadmium Sulfide shows bathochromic shifts
with increasing crystal size and solvent polarity, indicating that the electronic transition involved
Dipole moment of the ground and first excited state of the nanoparticle was
investigated. It was revealed that the solvatochromic responses were rather size dependent and
fine-tuning of the nanoparticles band gap is possible by appropriate choice of solvent environment. The radius determined from both X-ray diffraction and effective mass
approximation calculation was used in the determination of excited and ground state dipole
moments. It is observed that the excited state dipole moment is larger than its ground state and
the responses increased with the particle size up to a certain size beyond which the response
started to decrease again. The molar ratio 1:1 has largest dipole moment change value (21 D)
with Lippert-Mataga solvatochromic equation compared with other nanoparticle.
