In situ micro-Fourier transform infrared (FTIR) spectra of a typical cellulose nanofiber (CNF) film (i.e., CNF with cellulose I structure) were collected within the full relative humidity (RH) range from 0% to 90%. Red shifts of two peaks at 1036 and 1204cm(-1) and the variation of different spectra indicated the chemical adsorption sites for adsorbed water. From component band analysis of the spectral range of 2900-3700cm(-1), three component peaks at 3293, 3397, and 3543cm(-1) were due to strongly, moderately, and weakly hydrogen-bonded water. The signatures of these three types of hydrogen-...
