Understanding intermolecular energy transfer is important from both fundamental and applied perspectives. It is a process that determines thermal conductivity, an important property for applications such as cooling and lubrication. Our interest in vibrational energy transfer lies in the organization of fluid systems at the molecular level can influence the efficiency of vibrational energy transfer. We use one type of amphiphile that can for different assemblies in aqueous solution to determine how organization affects energy dissipation. Sodium decanoate was used as the amphiphile because it can form micelles or vesicles in aqueous solution, depending on the solution pH and the amphiphile concentration. Our results provide evidence that micelles and vesicles affect the dissipation of vibrational energy. Vibrational population relaxation data show the time constant for intermolecular energy transfer from perylene to the amphiphile aliphatic chain differs by a factor of two for micelles and vesicles, and is more efficient in micelles. Complementary measurements of transient heating in these same systems show that micelles experience higher temperature change than vesicles following the deposition of excess energy into the system by means of internal conversion from the S2 to S1 states of perylene. This finding indicates that the non-specific dissipation of energy from the amphiphile assembly to the aqueous bath is the same to within the experimental uncertainty for vesicles and micelles. This finding is in contrast to our findings for mode-specific vibrational energy transfer and is likely a consequence of the non-mode-specific nature internal conversion within the chromophore.
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