Proton-beam Analysis of Lichens
Dr. Lawrence Rees
Department of Physics and Astronomy
Brigham Young University
We are primarily familiar with lichens as the crusty growths on rocks or
tree bark, but they come in a variety of growth forms and can be found just
about anywhere on the earth. Because of their relatively simple structure
and their sensitivity to pollutants, lichens have been considered to be useful
as long-term monitors of environmental quality.
Over the past several years, we have conducted an extensive study of lichens
using such accelerator-based techniques as particle-induced x-ray emission
(PIXE) spectroscopy, microbeam PIXE, and accelerator mass spectroscopy (AMS).
Our principal aim has been to establish baselines of trace element concentrations
in a variety of lichens indigenous to western North America. In the
process, we have discovered some interesting things about the structure,
growth, and chemistry of lichens.