UV DAMAGE TO OPTICAL MATERIALS

WE PROPOSE TO INVESTIGATE THE MECHANISM OF UV PHOTO-INDUCED DAMAGED INOPTICAL MATERIALS. THIS OBJECTIVE REQUIRES THE USE OF A TUNABLE UV UNDULATOR SOURCE WHICH HAS SUFFICIENTLY HIGH FLUX TO EXPOSE SAMPLE OPTICS, AND APPROPRIATE SURFACE DIAGNOSTICS TO IDENTIFY THE ELECTRONICPROCESSES AND STRUCTURAL CHANGES WHICH ACCOMPANY THE INCREASED ABSORP-TION. IN PHASE I OF THIS EFFORT, WE WOULD DESIGN THE MODIFICATIONS REQUIRED FOR A SAMPLE INTRODUCTION AND IN SITU ABSORPTION MEASUREMENT APPARATUS WHICH WOULD BE MOVED FORM THE ORSAY UNDULATOR NOEL TO THE WUNDER MACHINE AT SSRL, AND DESIGN THE SURFACE DIANOSTICS TO BE ADDED TO THE APPARATUS. IN PHASE II, WE WOULD INSTALL THESE MODIFICATIONS AND CARRY FORWARD AN EXPERIMENTAL PROGRAM TO IDENTIFY THE UV DAMAGE MECHANISM; MEASURE ITS SCALING CHARACTERISTICS WITH PARTIAL PRESSURE, UV INTENSITY, AND SAMPLE TEMPERATURE; AND INVESTIGATE COUNTERMEASURES.