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Presented in this thesis are the results from an integrated experimental and modeling study on damage cascade formation in ion bombarded solids. The molecular dynamics (MD) simulations were performed by using LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). In one subtask, we studied damage cascade interactions caused by two 2 keV Si atoms simultaneously bombarding a crystalline Si substrate. We found that the enhanced displacement creation appears primarily in the thermal spike stage with all atoms at energies less than the displacement threshold. The study lead to the conclusion that the cascade interactions increased local melting by increasing energy deposition density, thus promoting defect creation. In another subtask, we studied radiation damage in Si0.8Ge2 layer caused by Agn clusters with number of atoms in a cluster, n, taking values from 1 to 4. It showed that strained SiGe, a material known to have poor radiation tolerance, still follows the overlap model, rather than the direct amorphization model. In the third subtask, MD simulation has shown that crowdion defects formed in bcc Fe are propagating along <111> directions. Crowdion defect starts to form when damage cascade reaches the maximum volume and contributes a second peak in defect buildups with increasing times. Upon defect recombination, crowdion defects shrink and form <111> oriented dumbbell defects at the crowdion end. In subsequent structural relaxation, <111> dumbbell defects rotate and finally align themselves with <110> directions. The surviving dumbbell defects represent a significant contribution to the final defect distribution after thermal spike formation. The overall research reveals atomic scale details of damage buildups at early stages of defect developments. Although the target systems cover both semiconductor materials and metal, these results show that MD simulation is a powerful tool to show the details at a spatial and time scale beyond experiments. These details are very important to develop understanding the precursor formation in defect clustering in such a case.

- Alicyclic diols can hydrogen bond in many different ways and yield most interesting structures. In this thesis, eight C2-symmetric diols 48-50, 78, 79 and 81-83 were synthesized and their crystal structures were determined. No less than seven of these show unusual solid state behaviour: 48 and 78 are inclusion hosts; 49, 50 and 78 form doubly-stranded hydrogen-bonded ladder structures, where there is a strong preference for each strand to be homochiral; 78, 81 and 82 undergo self-resolution during recrystallization; and 83 forms chirally pure crystals (but the material is still racemic). - One of the favourable supramolecular synthons for hydroxy compounds is the (O-H)6 cycle of hydrogen bonds. When this cycle is formed by a racemic compound, its enantiomers alternate down-up-down etc. around the cycle. No case of an (O-H)6 cycle involving chirally pure hydroxy compounds is known. These observations indicate a strong preference for the (O-H)6 cycle being constructed from achiral or racemic molecules rather than from chirally pure hydroxyl compounds. Racemic (??)-48 and (??)-92 which are already known to form (O-H)6 cycles in the solid state were prepared in chirally pure form and their X-ray crystal structures determined. No (O-H)6 cycles were observed for these homochiral diols. These findings confirm that the (O-H)6 motif occurs only for achiral or racemic compounds. - Similarly, the edge-to-edge eight-membered aryl C-H???N dimer involves either achiral molecules or those of opposite chirality. No chirally pure dimers of this type are reported. Racemic compounds 42-44 that are known to pack using the C-H???N dimer were synthesized in chirally pure form. No edge-to-edge eight-membered aryl C-H???N dimers were formed in the solid state. Hence this supramolecular synthon is only favoured for achiral or racemic compounds only. - Other major conclusions are that the cause of self-resolution is due to packing energy. In some cases it is likely that solvent choice, or solvent plus temperature selection, can be used to control self-resolution.

- Alicyclic diols can hydrogen bond in many different ways and yield most interesting structures. In this thesis, eight C2-symmetric diols 48-50, 78, 79 and 81-83 were synthesized and their crystal structures were determined. No less than seven of these show unusual solid state behaviour: 48 and 78 are inclusion hosts; 49, 50 and 78 form doubly-stranded hydrogen-bonded ladder structures, where there is a strong preference for each strand to be homochiral; 78, 81 and 82 undergo self-resolution during recrystallization; and 83 forms chirally pure crystals (but the material is still racemic). - One of the favourable supramolecular synthons for hydroxy compounds is the (O-H)6 cycle of hydrogen bonds. When this cycle is formed by a racemic compound, its enantiomers alternate down-up-down etc. around the cycle. No case of an (O-H)6 cycle involving chirally pure hydroxy compounds is known. These observations indicate a strong preference for the (O-H)6 cycle being constructed from achiral or racemic molecules rather than from chirally pure hydroxyl compounds. Racemic (??)-48 and (??)-92 which are already known to form (O-H)6 cycles in the solid state were prepared in chirally pure form and their X-ray crystal structures determined. No (O-H)6 cycles were observed for these homochiral diols. These findings confirm that the (O-H)6 motif occurs only for achiral or racemic compounds. - Similarly, the edge-to-edge eight-membered aryl C-H???N dimer involves either achiral molecules or those of opposite chirality. No chirally pure dimers of this type are reported. Racemic compounds 42-44 that are known to pack using the C-H???N dimer were synthesized in chirally pure form. No edge-to-edge eight-membered aryl C-H???N dimers were formed in the solid state. Hence this supramolecular synthon is only favoured for achiral or racemic compounds only. - Other major conclusions are that the cause of self-resolution is due to packing energy. In some cases it is likely that solvent choice, or solvent plus temperature selection, can be used to control self-resolution.

Thesis (Ph. D.)--University of Washington, 1989. / Vita. Includes bibliographical references (leaves 221-225).

Thesis (Ph. D.)--University of Hong Kong, 2007. / Also available in print.

Thesis (Ph. D. in Chemistry)--Vanderbilt University, May 2008. / Title from title screen. Includes bibliographical references.

Thesis (M. Sc.)--University of Adelaide, 1989. / Includes bibliographical references (leaves [71-72]).