Pore-Width-Dependent Ordering of C ₂ H ₅ OH Molecules Confined in Graphitic Slit Nanospaces

The X-ray diffraction (XRD) of C 2 H 5 OH molecules confined in slit-shaped graphitic micropores of activated carbon fibers having different pore widths was measured at 303 K. The effect of the pore width in the range 0.7−1.1 nm on the molecular assembly structure of C 2 H 5 OH in the micropores was examined. The XRD patterns were analyzed by use of the electron radial distribution function (ERDF) analysis. The densities of C 2 H 5 OH molecular assemblies in micropores were determined by C 2 H 5 OH adsorption at 303 K and N 2 adsorption at 77 K. The density of C 2 H 5 OH molecular assemblies in the 0.9 and 1.1 nm pores was close to the solid density of C 2 H 5 OH. The ERDFs showed that the first and second nearest-neighbor peaks shift to a shorter distance with a decrease of the pore width while their peak heights increase. These changes of the ERDFs coincided very well with the adsorbed density of C 2 H 5 OH, indicating that the serious confinement by the micropores gives rise to the solidlike ordering even at 303 K.