Diarylethenes with Electro-active Substituents for Optical Memories: A Theoretical Study and the Realization of a Memory with a Readout in the Mid Infrared

ABSTRACT

Since photochromic molecules occur as two stable forms, they can be used to make optical memories. The readout process must preserve the information stored and can be carried on by using mid-IR light and exploiting the differences in the IR spectrum between the two forms. Three diarylethenes with different electroactive lateral substituents have been studied theoretically (B3LYP 6-31G**) to understand the effect of the substituent on the difference in absorbtion intensities of the vibrational spectrum. Calculations show that the presence of a donor group in the molecule enhances the absorbtion intensity of some normal modes of the molecule in the closed form. The molecule with a donor side group has been synthesized, a film was deposited on a substrate, a simple setup with a multibolometer camera has been built and patterns written on the film were read.

Keywords:

• DFT
• diarylethenes
• infrared spectroscopy
• optical memories

Acknowledgments

This work was partly supported by the Fondazione Cariplo (Italy) through the “Research Projects on qualifying technologies”, by the Italian Scientific and Technological Research Ministry through the Centre of Excellence on Engineering of the nanostructured materials and surfaces (CISMUNA) and DOE PAIR.