Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/7/1999
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: Soft x-ray microscopes offer especially favorable contrast mechanisms for studying colloidal systems. The energy range of the water window between oxygen and carbon K absorption edges (543 and 284 eV) is of particular interest for studies on hydrated samples. In addition, x-ray absorption edges can be used to visualize and map compounds containing these elements versus other compounds. We used soft x-ray microscopy to image hydrated clays, to obtain contrast based on elemental composition (C, Ca), and to highlight C chemical states. Polyacrylamide is a flocculent that is added to irrigation water to reduce erosion and increase water efficiency. We used the scanning transmission x-ray microscope to visualize the flocculation of a KGa-1 kaolinite clay suspension at various concentrations of polyacrylamide. The results are in good agreement with the concentrations needed for field application, yet provide a very direct way of visualizing the effects of the flocculent. Other work includes looking at marine sediments. In the port of New York/New Jersey, a large fraction of marine sediment, that needs to be dredged from navigational channels is contaminated. This sediment has been imaged in a hydrated state near carbon absorption edge and carbonaceous material has been mapped. Current studies deal with analyzing the carbon contaminants in the contaminated sediment by C- XANES.