It is suggested that hydrogen atoms readily from sigma* bonds (three-electr
on bonds) to water molecules (H-.-OH2). It is well established that H-hal(-
.) adducts form with halide ions, and the species in water are thought to b
e comparable. Muonium atoms were also studied in frozen aqueous media. A ra
nge of data are presented and some consequences are outlined. Copyright (C)
2000 John Wiley & Sons, Ltd.