M. Sastry et al., LANGMUIR-BLODGETT-FILMS OF CARBOXYLIC-ACID DERIVATIZED SILVER COLLOIDAL PARTICLES - ROLE OF SUBPHASE PH ON DEGREE OF CLUSTER INCORPORATION, JOURNAL OF PHYSICAL CHEMISTRY B, 101(25), 1997, pp. 4954-4958
In this paper, we demonstrate that reasonably ordered multilayer films
of silver clusters can be deposited by the Langmuir-Blodgett (LB) tec
hnique. The approach consists of electrostatically immobilizing negati
vely charged carboxylic acid derivatized silver colloidal particles at
the air-water interface using positively charged fatty amine Langmuir
monolayers. The degree of cluster incorporation into the Langmuir mon
olayer has been controlled by varying the charge on the amine molecule
s through the colloidal subphase pH. Pressure-area isotherms were used
to follow adsorption of the silver colloidal particles at the amine s
urface, while quartz crystal microgravimetry (QCM), optical absorption
spectroscopy, infrared spectroscopy, contact angle measurements, and
optical interferometry were used to characterize the multilayer LB fil
ms, The films were found to grow in the classical Y-type mode, Optical
interferometry indicated a bilayer thickness of 106 Angstrom, which y
ields a cluster size of similar to 55 Angstrom, in reasonable agreemen
t with a mean cluster size of 73 Angstrom determined from transmission
electron microscopy. Incorporation of clusters into inorganic matrice
s as outlined in the paper shows promise for the growth of superlattic
e structures, mixed cluster systems, etc., which are not realizable by
currently used experimental methods.