1. Facultad de Física, Pontificia Universidad Católica de Chile, Santiago 22, Chile
2. Department of Physics and Astronomy and University of Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211
3. Department of Chemistry, Technical University of Denmark, IK-207 DTU, DK-2800 Lyngby, Denmark
4. Advanced Optowave Corporation, 1170 Lincoln Avenue, Unit# 10, Holbrook, New York 11741
5. National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973