AUTHOR=Townsend Tiana , Schwartz Charles J. , Jochim Bethany , P. Kanaka Raju , Severt T. , Iwamoto Naoki , Napierala J. L. , Feizollah Peyman , Tegegn S. N. , Solomon A. , Zhao S. , Carnes K. D. , Ben-Itzhak I. , Wells E. 

TITLE=Controlling H3+ Formation From Ethane Using Shaped Ultrafast Laser Pulses

JOURNAL=Frontiers in Physics

VOLUME=Volume 9 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2021.691727

DOI=10.3389/fphy.2021.691727

ISSN=2296-424X

ABSTRACT=An adaptive learning algorithm coupled with 3D momentum-based feedback is used to identify intense laser pulse shapes that control H$_3^+$ formation from ethane.    Specifically, we controlled the ratio of D$_2$H$^+$ to D$_3^+$ produced from the D$_3$C-CH$_3$ isotopologue of ethane, which selects between trihydrogen cations formed from atoms on one or both sides of ethane. We are able to modify the D$_2$H$^+$:D$_3^+$ ratio by a factor of up to three.  In addition, two-dimensional scans of linear chirp and third-order dispersion are conducted for a few fourth-order dispersion values while the D$_2$H$^+$ and D$_3^+$ production rates are monitored.  The optimized pulse is observed to influence the yield, kinetic energy release, and angular distribution of the D$_2$H$^+$ ions while the D$_3^+$ ion dynamics remain relatively stable.  We subsequently conducted COLTRIMS experiments on C$_2$D$_6$ to complement the velocity map imaging data obtained during the control experiments and measured the branching ratio of two-body double ionization. Two-body D$_3^+$ + C$_2$D$_3^+$ is the dominant final channel containing D$_3^+$ ions, although the three-body D + D$_3^+$ + C$_2$D$_2^+$ final state is also observed.