CONTROLLED GROWTH OF THE ORDERED CADMIUM-SULFIDE PARTICULATE FILMS AND THE PHOTOACOUSTICS INVESTIGATION

Two kinds of cadmium sulfide (CdS) particulate films have been generat ed in situ by exposing stearic acid (SA) Langmuir monolayer at the air -aqueous CdCl2 interface to hydrogen sulfide (H2S) gas: particulate fi lms composed of oriented rodlike nanocrystals (A-type particulate film s), and those of dotlike nanocrystals which formed a stripelike domain with straight edges aligned with B-fold symmetry (B-type particulate films). The SA-coated CdS particulate films were transferred to a soli d substrate and examined by transmission electron microscopy (TEM) and photoacoustic spectroscopy (PAS). The dark field image and the transm ission electron diffraction of the TEM were used to study the morpholo gy and growth mechanisms of the CdS particulate films in detail. The P AS of the CdS particulate films composed of the oriented rodlike nanoc rystals shows a new peak at 417.5 nm. This peak implies some new physi cal phenomena corresponding to the ordered alignment of the semiconduc tor nanocrystals, which exists in the ordered nanosystems. The novel s ynthesis method described here leads to the fabrication of the highly oriented semiconductor quantum wires and provides a new method to inve stigate the structure of the Langmuir monolayer at the air-water inter face.