What the stretch frequency spectrum of D2O/Ru(0001) does and does not mean

Based on O-D stretch frequencies, Denzler et al., reject partial dissociation of D2O molecules as the explanation of the measured structure of root3 x root3 - D2O/Ru(0 0 0 1). But it is largely the O-O distance that determines the O-D stretch frequency in an O-D...O bond of an H-bonded network. Thus, a D2O adlayer's stretch spectrum reflects its O-O distances, not its proportion of intact vs. dissociated molecules. This idea suggests that deuteron disorder in the heavy-water adlayer is the key to understanding its broad O-D stretch spectrum. (C) 2004 Elsevier B.V. All rights reserved.