ABSTRACT
Introduction ........................................................................................................ 101
Fourier Transform Raman Spectroscopic Study of the Interaction of
Water Vapor with Amorphous Polymers .................................................. 102
Water Diffusion in Hydrated Crystalline and Amorphous Sugars
Monitored Using H/D Exchange ............................................................... 107
Acknowledgments ............................................................................................. 112
References ........................................................................................................... 112
Vibrational spectroscopy has a long history of use for the investigation of
water structure and the interaction of water with other materials (Kusanagi
and Yukawa, 1994; Maeda and Kitano, 1995; Walrafen, 1971). In the gas state,
the peaks arise from combinations of three vibrations: symmetric and
asymmetric OH stretch and OH deformation. In the condensed state, the
vibrational spectra are far more complex because of vibrational overtones
and combinations with librations (restricted rotations; i.e., rocking motions)
resulting from hydrogen bonds. Thus, there is a wealth of information
contained in the spectrum of water. There are at least three ways in which
water-solid interactions can be investigated using vibrational spectroscopy.
First, the change in the water peaks upon interaction with the solid can be
assessed and interpreted to provide information about the structure of water
in the system. For example, the OH stretching peak position of the water
molecule has been correlated to the strength of the hydrogen bonding
between water and solid in crystalline hydrates (Falk and Knop, 1973).
Second, the change in the vibrational spectrum of the solid can be
investigated in the presence of water to extract information about structural
changes. Third, the dynamics of water-solid interactions can be probed by
monitoring spectral changes as a function of time under carefully controlled
environmental conditions. Dynamics have been investigated in a number of
systems includingmonitoring of the phenomenon of deliquescence (Cantrell
et al., 2002) and the exchange of D
