Abstract
The rotational relaxation of perylene and tetracene in hexadecane has been studied at several temperatures by femtosecond fluorescence upconversion. The initial emission anisotropy values of both D2h symmetric fluorophores are now found to be very close to the theoretical value of 0.4, and the anisotropy decay observed with subpicosecond time resolution can no longer be described as a biexponential. The traditional in-plane and out-of-plane rotational diffusion time constants of perylene in hexadecane are verified to be linearly dependent on viscosity/temperature. Moreover, a third, ultrafast rotation, empirically fit to a time constant of ∼ 450 fs for perylene and ∼600 fs for tetracene, has been found. It is independent of temperature and viscosity, and the amplitude (“βfast”) explains the previously described “r0 defect ”. Since βfast is ∼0.03 for tetracene vs ∼0.05 for perylene, we presently suggest that “in-plane” femtosecond libration of the molecules within a solvent pocket yields the observed anisotropy.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
