Widening of the hydrogen bonded OH-streching bands due to the wagging and OO-stretching modes in H2O·H2O

►Coupling of OH-stretching with HOH-acceptor wagging mode causes transition intensity to be distributed over a wider range. ► The width increases with OH-stretching excitation. ► The HOH-acceptor wag and OO-stretch both contribute and in a different way. ► The overall effect is to lower maximum absorbance significantly. ► The effective width of the third OH-stretching overtone becomes around 400 cm-1 .