A fused silica microbalance for the study of vacuum deposition process

A silica torsion microbalance of a sensitivity of 1·37 × 10 −7 g mm −1 and a capacity of 60 mg has been constructed for study of the vacuum deposition process. Since the experimental apparatus has been so designed that it may be insensitive to the impulsive force of impinging particles, the weight change of deposits can be followed continuously from the beginning of deposition. The smallest detectable thickness of a thin film has attained 1/20 of a monolayer for bismuth by the use of a substrate of 10·2 cm 2 in area. An application of the balance to the study of gas adsorption on a mica surface is also reported.