Three Bits Eight States Photochromic Recording and Nondestructive Readout by Using IR Light

A photochromic polymer film containing three different diaryle- thene derivatives, that is, 1,2-bis(3,5-di- methyl-2-thienyl)perfluorocyclopentene (1), 1,2-bis(2,5-dimethyl-3-thienyl)per- fluorocyclopentene (2), and 1,2-bis(2- methyl-5-phenyl-3-thienyl)perfluorocy- clopentene (3) was prepared. Upon UV irradiation, the three derivatives changed to their closed-ring isomers having different colors, yellow, red, and blue. They showed different spectra not only in UV/Vis region but also in the IR spectral region. Upon irradia- tion with visible light of appropriate wavelengths, each closed-ring isomer was selectively bleached, and three bits eight states recording was performed. The eight states could be read out non- destructively by using IR light of ap- propriate wavenumbers.