Investigation of enhanced third-order optical nonlinearity in novel coenzyme A capped silver nanoparticles

In this paper, we report the design and synthesis of novel coenzyme A (CoA)-capped silver nanoparticles and the investigation of their third-order nonlinear optical properties. Computational studies were carried out to understand the feasibility of forming CoA-capped nanoparticles, which indicated successful stabilization of silver nanoparticles upon surface functionalization with coenzyme A. The synthesis of CoA-capped silver nanoparticles was carried out by chemical reduction of silver nitrate by sodium borohydride in the presence of heat. The appearance of the surface plasmon resonance peak at 429 nm confirmed the formation of silver nanoparticles. TEM, SEM, DLS, and Zeta potential analyses showed the formation of polydispered spherical-shaped nanoparticles with CoA capping. The third-order nonlinear susceptibilities were measured using the degenerate four-wave mixing (DFWM) technique. The CoA-capped silver nanoparticles exhibited a higher nonlinear susceptibility than the traditionally used borohydride-capped silver nanoparticles. The enhanced nonlinearity was attributed to the localised surface plasmon resonance (LSPR) of the silver nanoparticles and the electron density distribution at the interface of the nanoparticles and the capping agent. The optical properties of the CoA-capped nanoparticles can open up avenues for the use of metal nanoparticles with bulkier capping agents in optoelectronic applications. Coenzyme A-capped silver nanoparticles were synthesised using chemical reduction and their enhanced third order nonlinear susceptibility was investigated using degenerate four wave mixing studies.