Total internal reflectance-infrared structural studies on tensile water formation during evaporation from nanopores

Attenuated total reflectance (ATR) infrared spectroscopy of water evaporating from within a TiO2 nanolayer with pores of a mean diameter of 23 nm is applied to detect the transition to the tensile state where water molecules are stretched. It is seen how the concentration of the strongly H-bonded (network) water population, measured within the OH-stretching band, is strongly increasing at the expense of the medium (intermediate) H-bonded population. This observation suggests that water molecules exposed to tensile stress (in nanoenvironments) get involved in additional H-bonding, generating a sigmoid (autocatalytic) growth of the network water population. Such a feedback mechanism is related to known molecular electronic properties and to irreversible thermodynamic concepts of water. Reference is made to the solar powered water ascent in trees, where this phenomenon of tensile water has evolved into a working technology.