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A photochemistry study on nitrous oxide making use of site-selective excitation of terminal nitrogen, central nitrogen, and oxygen 1s -> 3 pi excitations is presented. The resonant Auger decay which takes place following excitation can lead to dissociation of the N2O+ ion. To elucidate the nuclear dynamics, energy-resolved Auger electrons were detected in coincidence with the ionic dissociation products, and a strong dependence of the fragmentation pathways on the core-hole site was observed in the binding energy region of the first satellite states. A description based on the molecular orbitals as well as the correlation between the thermodynamical thresholds of ion formation and the first electronic states of N2O+ has been used to qualitatively explain the observed fragmentation patterns.

Decay spectra of N2O following excitation to the N terminal (Nt) → π*, N central (Nc) → π* and O is → π* intermediate states are reported. The final states reached after participator decay show resonant enhancement consistent with a local-density-of-states analysis based on the Mulliken population of the valence molecular orbitals. In particular, the X-state is resonantly enhanced mostly after excitation from the Nt 1s and the O Is core levels to the π*, while the B-state is mostly enhanced following the excitation of the Nc Is → π* intermediate state. Below the Nt Is threshold, the lowest lying peak related to spectator decay falls at lower binding energy than the highest lying participator peak. This can be attributed to a particularly strong screening effect exerted by the excited electron in the LUMO.

Case studies are presented of instances when acid mine drainage from waste rock dumps has presented an environmental problem in Australia. Acid generation occurs in waste rocks from the mining of a wide range of minerals and in climates ranging from the tropical north to the temperate southeast. Most of the case studies are of abandoned mines but one, Woodlawn, is an operating mine. Techniques used to reduce the problem by inhibiting pollutant transport from the wastes are described and the effectiveness of the techniques discussed. These range from relatively simple establishment of vegetation on the dumps to reshaping and the emplacement of a multi-layer seal. Long-term monitoring is essential to verify the effectiveness of rehabilitation. Recent advances in modelling the pollutant generation mechanism are described and the utility of models in assessing schemes to inhibit pollution generation discussed., Case studies are presented of instances when acid mine drainage from waste rock dumps has presented an environmental problem in Australia. Acid generation occurs in waste rocks from the mining of a wide range of minerals and in climates ranging from the tropical north to the temperate southeast. Most of the case studies are of abandoned mines but one, Woodlawn, is an operating mine. Techniques used to reduce the problem by inhibiting pollutant transport from the wastes are described and the effectiveness of the techniques discussed. These range from relatively simple establishment of vegetation on the dumps to reshaping and the emplacement of a multi-layer seal. Long-term monitoring is essential to verify the effectiveness of rehabilitation. Recent advances in modelling the pollutant generation mechanism are described and the utility of models in assessing schemes to inhibit pollution generation discussed.