Enhancing the feedback signals used in closed-loop control of molecular fragmentation
POSTER
Abstract
Using CO as a prototype system, the role of the feedback signal is examined in a closed-loop coherent control technique utilizing ultrafast laser pulse shaping coupled to a genetic algorithm. We control the fragmentation branching ratio of CO$^{+}$ or CO$^{2+}$ with a feedback signal obtained from a time-of-flight spectrometer. Optimization of the ratio of (C$^{+}$ + O)/(C + O$^{+})$ using a signal that integrated all of the C$^{+}$ fragments produced a different optimal pulse than when the kinetic energy release was used to separate the C$^{+}$ + O and C$^{+}$ + O$^{+}$ channels. Feedback signals obtained using particle counting detection rather than current mode were used to optimize low-probability channels, such as CO$^{2+}$, suggesting the possibility of incorporating coincidence measurements into feedback loops.
*This work was supported by National Science Foundation award PHY-0653598 and the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Science, US Department of Energy.