Investigation of 3D ORAM Materials for Radiation Dosimetry

Abstract

Three-dimensional optical random access memories (3D ORAM) are bistable photochromic materials that can be converted from the stable non-fluorescent form to the quasi-stable fluorescent form via two-photon absorption using intersecting laser beams. To investigate heavy charged particle (HCP) radiation effects on these materials, thin films of spyrobenzopyran-doped polymethylmethacrylate (SP/PMMA) were exposed to 0.6-2.5 MeV protons, 2 MeV and 5 MeV alpha particles, and 6.5 MeV 12C ions at fluences ranging from 1010 to 1014 cm-2. Exposed films were optically sectioned with a confocal laser scanning microscope (CLSM) and radiation effects were evaluated by measuring fluorescent intensity verses depth. Radiation exposure of the non-fluorescent form of SP/PMMA resulted in a permanent change, leaving fluorescent tracks excitable by optical wavelengths. Depth profiles revealed a correlation between maximum fluorescent intensity and absorbed dose. Additionally, the full width at half maximum (FWHM) of the depth profiles could be related to the incident HCP energy per nucleon.