Photochemically induced phase transition of immobilized bilayer membrane

Spectral bistability of an immobilized bilayer membrane will be described in connection with an optical memory material. An ordered cast film of an azobenzene-containing bilayer membrane shows a peculiar solid-solid phase transition. A large spectral shift of the azobenzene chromophore form 300 nm to 370 nm is found during the thermal phase transition. Due to the large thermal hysteresis, the spectral bistability required for stable optical recording is achieved under dry conditions. An isothermal transition from 370 nm to 300 nm is triggered by moisture treatment. The transition cycle between 300 nm and 370 nm is completely reversible. Photoirradiation with a UV light in the dry condition induces photochemical trans-cis isomerization of the azobenzene chromophore which triggers the isothermal transition to 300 nm. Details of the photoinduced phase transition will be discussed.