Organic secondary-ion mass spectrometry, molecular imaging, and electron-stimulated desorption
A commercial secondary ion mass spectrometer (SIMS) has been used to image, for the first time, the distribution of fragile organic molecules on metal substrates and in frozen aqueous solution. Intact molecular ions have also successfully been sputtered from biological tissue. Various modification have been made to the ion microscope including extension of the mass range from 300 amu to 1100 amu. Primary ion beam damage processes are explored in some detail. It has been found that many compounds offer substantial resistance to primary beam damage. This damage resistance results from the high sputter yields found in these materials. Studies of primary beam damage processes in glycerol have clarified in the mechanisms of the damage resistance in liquid matrices. The electron stimulated desorption (EDS) of atoms and ions from surfaces is a well known phenomenon. However, the practical applications of this technique have not been explored in great detail. Using the ion microscope, the distribution of a number of surface adsorbates and contaminants with 1 ..mu..m lateral resolution have been imaged. ESD sensitivities for a number of elements can be higher than SIMS, particularly for hydrogen and the halogens. ESD images are found to contain more topographical information that sputtered ion images. The ESD imaging work has led to a fundamental study of the physics of the desorption process and the first observation of highly charged electron desorbed ions.
- Research Organization:
- Arizona State Univ., Tempe (USA)
- OSTI ID:
- 6597840
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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