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

A photochromic polymer film containing three different diarylethene derivatives, that is, 1,2‐bis(3,5‐dimethyl‐2‐thienyl)perfluorocyclopentene (1), 1,2‐bis(2,5‐dimethyl‐3‐thienyl)perfluorocyclopentene (2), and 1,2‐bis(2‐methyl‐5‐phenyl‐3‐thienyl)perfluorocyclopentene (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 irradiation 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 nondestructively by using IR light of appropriate wavenumbers. A nondestructive read‐out of multi‐frequency photochromic recording was performed by using IR light of appropriate wavenumbers for a polymer film containing three different kinds of diarylethene derivatives. The assignments of the IR bands of the derivatives are also reported.