1. Australian Centre for Neutron Scattering; Australian Nuclear Science and Technology Organisation; New Illawarra Road Lucas Heights New South Wales 2234 Australia
2. School of Chemistry; The University of Sydney; Sydney New South Wales 2006 Australia
3. School of Chemistry; Monash University; Melbourne Victoria 3800 Australia
4. Present address: School of Chemical and Physical Sciences; Keele University; Staffordshire ST5 5BG UK