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=9

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=<p>An adaptive learning algorithm coupled with 3D momentum-based feedback is used to identify intense laser pulse shapes that control <inline-formula id="inf3"><mml:math id="m3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi mathvariant="normal">H</mml:mi><mml:mi mathvariant="normal">3</mml:mi><mml:mi mathvariant="normal">+</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> formation from ethane. Specifically, we controlled the ratio of D<sub>2</sub>H<sup>+</sup> to <inline-formula id="inf4"><mml:math id="m4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi mathvariant="normal">D</mml:mi><mml:mi mathvariant="normal">3</mml:mi><mml:mi mathvariant="normal">+</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> produced from the D<sub>3</sub>C-CH<sub>3</sub> 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<sub>2</sub>H<sup>+</sup>:<inline-formula id="inf5"><mml:math id="m5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi mathvariant="normal">D</mml:mi><mml:mi mathvariant="normal">3</mml:mi><mml:mi mathvariant="normal">+</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> 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<sub>2</sub>H<sup>+</sup> and <inline-formula id="inf6"><mml:math id="m6" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi mathvariant="normal">D</mml:mi><mml:mi mathvariant="normal">3</mml:mi><mml:mi mathvariant="normal">+</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> production rates are monitored. The optimized pulse is observed to influence the yield, kinetic energy release, and angular distribution of the D<sub>2</sub>H<sup>+</sup> ions while the <inline-formula id="inf7"><mml:math id="m7" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi mathvariant="normal">D</mml:mi><mml:mi mathvariant="normal">3</mml:mi><mml:mi mathvariant="normal">+</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> ion dynamics remain relatively stable. We subsequently conducted COLTRIMS experiments on C<sub>2</sub>D<sub>6</sub> to complement the velocity map imaging data obtained during the control experiments and measured the branching ratio of two-body double ionization. Two-body <inline-formula id="inf8"><mml:math id="m8" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi mathvariant="normal">D</mml:mi><mml:mi mathvariant="normal">3</mml:mi><mml:mi mathvariant="normal">+</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> + <inline-formula id="inf9"><mml:math id="m9" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi mathvariant="normal">C</mml:mi><mml:mi mathvariant="normal">2</mml:mi></mml:msub><mml:msubsup><mml:mi mathvariant="normal">D</mml:mi><mml:mi mathvariant="normal">3</mml:mi><mml:mi mathvariant="normal">+</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> is the dominant final channel containing <inline-formula id="inf10"><mml:math id="m10" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi mathvariant="normal">D</mml:mi><mml:mi mathvariant="normal">3</mml:mi><mml:mi mathvariant="normal">+</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> ions, although the three-body D + <inline-formula id="inf11"><mml:math id="m11" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi mathvariant="normal">D</mml:mi><mml:mi mathvariant="normal">3</mml:mi><mml:mi mathvariant="normal">+</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> + <inline-formula id="inf12"><mml:math id="m12" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi mathvariant="normal">C</mml:mi><mml:mi mathvariant="normal">2</mml:mi></mml:msub><mml:msubsup><mml:mi mathvariant="normal">D</mml:mi><mml:mi mathvariant="normal">2</mml:mi><mml:mo>+</mml:mo></mml:msubsup></mml:mrow></mml:math></inline-formula> final state is also observed.</p>