Coherent Phase Control of Internal Conversion in Pyrazine

Shaped ultrafast laser pulses were used to study and control the ionization dynamics of electronically excited pyrazine in a pump and probe experiment. For pump pulses created without feedback from the product signal, the ion growth curve (the parent ion signal as a function of pump/probe delay) was described quantitatively by the classical rate equations for internal conversion of the $S_2$ and $S_1$ states. Very different, non-classical behavior was observed when a genetic algorithm (GA) was used to minimize the ion signal at some pre-determined target time, T. Two qualitatively different control mechanisms were identified for early (T$ 1.5$ ps) target times. In the former case, the ion signal was largely suppressed for $t 1.5$ ps the ion growth curve followed the classical rate equations for $t

Keywords:

• Ultrashort pulse
• Atomic physics
• Excited state
• Absorption cross section
• Ionization
• Photon energy
• Ion
• Physics
• Internal conversion
• Ionization energy

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