Poster Femtosecond dynamics in Confined Systems A. Douhal*, M.A. Carranza, M. Sanz and J.A. Organero Departamento de Química física, Sección de Químicas, Fac. de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Avda. Carlos III, S.N. 45071 Toledo (Spain). [email protected] Ultrafast dynamics of molecular systems in confined media has large effect on the space and time domain behaviours of nanostructures (1). In this Lecture, we will present and discuss recent results of femtosecond studies of single and double proton transfer reactions in confined media provided by nanocavities of cyclodextrins and micelles. We examined in real time of reactions (proton transfer events) the effect of confinement on the nanostructure dynamics. The results show an ultrafast (less than 100 fs) first step giving birth to an intermediate which shows femtosecond and hundreds of picosecond dynamics leading to the final structure at the excited state. To study the energy barrier and tunnelling on the dynamics in both solution and nanostructures, we have also examined the effects of isotope (H/D) and excess energy of excitation when observing at different wavelengths of the emission spectrum. The results clearly show that confined water in nanostructure has a very slow (ps regime) dynamics. We believe that the obtained data are relevant to understanding the behaviour of nanodevices where confinement plays a key role in their function and stability. References: For recent review see for example: A. Douhal, Ultrafast Dynamics in Cyclodextrin Nanocavities, Chem. Rev. 2004, 104, 1955. Acknowledgements: This work was supported by the Ministry of Science and Technology (MCYT, Spain) and “Consejeria de Ciencia y Tecnologia de la JCCM, Spain” through projects MAT-2002-01829 and PAI-02-004. TNT2004 September 13-17, 2004 Segovia-Spain .