Infrared Studies of Hydrogen Bonding of Water by the Matrix Isolation Technique

The stretching and bending vibrational modes of the hydrogen bonded polymers of water have been studied by the matrix isolation technique using solid nitrogen at 20°K as a matrix. Absorptions are assigned to water monomers (3725, 3627, and 1600 cm—1), to dimers (3691, 3546, and 1620 cm—1) and to higher polymers (3510, 3355, 3318, 3222, and 1633 cm—1). The frequencies suggest that the dimers have cyclic rather than open (or bifurcated) structures. The absorption coefficients of the bending modes decrease slightly in the higher polymers while those of the stretching mode increase by a factor of about twelve. This intensity behavior cannot be explained solely on the basis of enhanced ionic character of the O–H group in the hydrogen bond.