[Todos] Seminario DQIAyQF/INQUIMAE- Miercoles 26, 13h

[sara elizabeth bari]

Seminarios del Dpto. de Química Inorgánica, Analítica y Química Física / INQUIMAE
FCEyN - Universidad de Buenos Aires

http://www.qi.fcen.uba.ar/es 

1er. Cuatrimestre, 2006

        



  Miercoles 26 de Abril, 13h

Aula de Seminarios del Departamento de Química Inorgánica, Analítica y Química Física, FCEyN, UBA

Ciudad Universitaria, Pabellón II, Piso 3

  


  

Daniel Kuroda

Department of Chemistry, University of Florida

Gainesville, Fl, 32611-7200 

       Controlling Fluorescence Quantum Efficiency With Femtosecond Laser Pulses 





   We present here the coherent control of the fluorescence quantum efficiency of Rhodamine 6G in solution. 

   In this work we demonstrate control over solution photochemistry using a novel tool based on the coherent properties of the excitation field. To achieve control over a photochemical process, ultrafast pulses with a particular time and frequency relationship are needed. These pulses are intrinsically defined by the target potential energy surfaces. Since full knowledge of the required molecular properties is unattainable, optimization algorithms with feedback loops have been used to find the excitation electric field leading to the control of the process. 

   In our experiments, a liquid crystal pulse shaper is used to modulate the phase of the excitation pulse, and a closed loop genetic algorithm searches for the best pulse to control the system. Using fluorescence and second harmonic generation as feedback signals, we successfully control the fluorescence quantum efficiency of Rhodamine 6G in solution. Through the analysis of the excitation pulses we are able to obtain molecular information about Rhodamine 6G. 
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