Nanoscale growth of CdS and PbS semiconductor within calix4arene Langmuir- Blodgett LB film for ion sensing application

摘要

The characteristics of cadmium sulphide (CdS) and lead sulphide (PbS) nanoparticles, grown inside Langmuir-Blodgett (LB) multilayer films of 5,11,17,23-tetra-tert-butyl-25,27-dicarboxymethoxy-26,28-dihydroxycalix[4]arene (I), have been studied using ellipsometry, UV-visible spectroscopy, and transmission electron microscopy (TEM). Multilayer films were formed by transferring a floating Langmuir monolayer of I onto substrates using LB deposition and water subphase containing Pb~(2+) or Cd~(2+) ions. The nanoparticles were growth by exposing cadmium- or lead-containing multilayer films of I (20-80 monolayers thick) to hydrogen sulphide (H_2S) gas for 12 hours. By Gaussian fitting of the absorbance - energy spectra, the size of the clusters and their dispersion were found to be 1.43±0.18 nm and 1.21±0.05 nm for CdS and PbS respectively. This is the first time that such thick LB films of an amphiphilic compound possessing such high thermal stability (m.pt. ~270°C) have been used as the vehicle for the formation of CdS and PbS semiconductor particles.