Document 3eexQNvpV7ErGEL6aym1EYNbE

DON'T SAT IT-WRITE IT ,_Tyv C, Rv Ginnard ............. --- --^-- AT__ FROM b * chase DATES 10/7/81 , At your request we tried to obtain Raman and infrared spectra on exposed and unexposed regions of some representative paint panels. For the Raman work, samples 1783-179*6 and 1783179-3 were used. With both 5145& excitation and 488Q& excitation excessive fluorescence was encountered. Attempts were made to quench the fluorescence by leaving the sample in the laser beam for several hours, but sample decomposition resulted. This high fluorescent background was more severe in the 0V exposed regions. All data were taken on a 5~ microprobe with photon counting detection, incident laser power was varied from 10 mwatts to 800 mwatts. Sample 1783-179-6 was used in an infrared specular reflection experiment . Incident angle was -*-'80 , The material behaved like a low quality mirror, i.e., a flat reflectance curve with no spectral features and an average reflectance of 30%. These data were obtained on a Nieolet 7199 interferometer. Neither technique showed any promise for measuring differences between exposed and unexposed paint panels. The most promising method, I believe, has been developed by Alan English and consists of abraiding off layers of the panel and obtaining diffuse reflectance infrared spectra on the powders. DUP030029643 DUP030029644