We report the results of an experimental study designed to establish whether, once formed, one of the isomer classes of the hydrated electron clusters, (H2O)n−, can interconvert with others when a water molecule is added by condensation. This is accomplished in an Ar-cluster mediated approach where a single intact D2O molecule is collisionally incorporated into argon-solvated water hexamer anions, creating the isotopically labeled D2O·(H2O)6−·Arn heptamer anion. Photoelectron and infrared predissociation spectroscopies are employed both to characterize the isomers generated in the condensation event and to track the position that the D2O label adopts within these isomeric structures. Despite the fact that the water hexamer anion precursor clusters initially exist in the isomer I form, incorporation of D2O produces mostly isomers I′ and II in the labeled heptamer, which bind the electron more (I′) or less (II) strongly than does the isomer I class. Isomers I and I′ are known to feature electron binding primarily onto a single water molecule that resides in an AA (A = H-bond acceptor) site in the network. Surprisingly, the D2O molecule can displace this special electron-binding H2O molecule such that the anionic cluster retains the high binding arrangement. In the more weakly binding isomer II clusters, the D2O molecule fractionates preferentially to sites that give rise to the vibrational signature of isomer II.
You have access to this article
Please wait while we load your content...
Something went wrong. Try again?