During a study of the integrated intensity of the 1600 cm−1 band of substituted benzenes, we wished to measure solution spectra of some aryl carbonium ions. These ions reacted rapidly with the usual cell window materials so it was necessary to develop an inert cell of uniform and constant path length which allowed accurate and reproducible intensity measurements to be made. We succeeded in this aim with a cell utilizing conventional NaCl windows covered with polytetrafluoroethylene (Teflon) sheeting and separated by a Teflon spacer, with stainless steel injection ports, so that the reactive solution was in contact with only Teflon and stainless steel.
T. J. Broxton, J. Chippindall, L. W. Deady, and R. D. Topsom, "An Inert Infrared Cell for Measuring Quantitative Solution Spectra of Carbonium Ions and Other Reactive Species," Appl. Spectrosc. 24, 382-383 (1970)