Comment on: Thickness Measurement of Built-Up Monolayers by Multiple Beam Interferometry R. Shirahata and G. D. Scott

Physics Department, University of Toronto, Toronto, Toronto, Ontario, M5S 1A7, Received 15 February 1973. It is useful to call attention to the papers of Srivastava

and Verma, which we had missed.1

In regard to the technique of employing an intermediate collodion layer in measuring films of built-up monolayers, our experience is that the quality of the fringes and hence the precision of the measurements are very significantly improved with its use. The work of Gaines and Roberts indicates that over 60% of a stearic acid film is removed by exposure to vacuum for 30 min. The related skeletoni­zation of barium stearate films would be expected to have a marked influence on the way the overcoating is deposit­ed.

Reference 1. V. K. Srivastava, Appl. Opt. 12, 936 (1973).

936 APPLIED OPTICS / Vol. 12. No. 5 / May 1973