a. Infrared absorption spectrum of the OD stretch of dilute HOD in H2O in several large AOT reverse micelles, bulk water, and the w0 = 2 reverse micelle. Water solid black line, w0 = 46 red, w0 = 37 green, w0 = 25 blue, and w0 = 2 dashed black line. b. Infrared absorption spectrum of the w0 = 25 reverse micelle and a two component fit consisting of the spectrum of bulk water and the spectrum of the w0 = 2 reverse micelle. The only adjustable parameter is the relative amplitude of the two spectra. The solid vertical line marks the peak of the w0 = 2 spectrum in both figures (2565 cm−1). The region with the largest contributions from interfacial water molecules will be at frequencies higher than this line.