There is considerable interest in developing optical data storage devices that integrate photochromic molecular switches as the storage medium. These light-sensitive compounds must efficiently switch in one direction for writing data with UV light, while maintaining a very low yield for the reverse process to allow non-destructive optical read-out of the data with visible light. Using two-photon excitation to increase the yield of the reverse process has the potential for making the data storage devices erasable; therefore, we have studied the two-photon properties of a common photochromic molecular switch. The compound, 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene (DMPT-PFCP), undergoes efficient electrocyclization to a closed-ring isomer under UV irradiation, and has a very low yield for cycloreversion following absorption of visible light. We have examined the spectroscopy and dynamics of DMPT-PFCP in order to assess the potential for using various two-photon accessible excited states to selectively control the outcome of the cycloreversion reaction. Two-photon absorption (2PA) spectroscopy measurements reveal the two-photon accessible states and their 2PA cross-sections. The second absorption band of the molecule has a larger 2PA cross-section than the lowest absorption band, which is typically the transition used for optical read-out with a single visible photon. Separate measurements of the two-photon quantum efficiency for cycloreversion and of the excited state dynamics following two-photon excitation collectively provide insight into the behavior of the two-photon accessible excited-states, and their ability to affect the cycloreversion reaction.

Two-photon spectroscopy, dynamics, and quantum yields of a photochromic molecular switch

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.