Native frames: An approach for separating sequential and concerted three-body fragmentation
T. Severt, Jyoti Rajput, Ben Berry, Bethany Jochim, Peyman Feizollah, B. Kaderiya, M. Zohrabi, Farzaneh Ziaee, Kanaka Raju P., Daniel Rolles, Artem Rudenko, K. D. Carnes, B. D. Esry, I. Ben-Itzhak
Abstract
Disentangling sequential and concerted three-body fragmentation has been a longstanding endeavor in studies of molecular dynamics. To accomplish this goal, we recently introduced a novel method to separate sequential from concerted breakup, where the sequential events are analyzed in their native frames [J. Rajput et al., Phys. Rev. Lett. 120, 103001 (2018)]. The essence of this method is the use of the Jacobi coordinates' conjugate momenta to reduce the dimensionality of the multibody fragmentation in combination with a clear signature for sequential breakup. To demonstrate this method, we employ coincidence momentum imaging to study the strong-field dissociative ionization of OCS into ${\mathrm{O}}^{+}+{\mathrm{C}}^{+}+{\mathrm{S}}^{+}$, which typically undergoes concerted fragmentation or sequential breakup involving either a metastable ${\mathrm{CO}}^{2+}$ or ${\mathrm{CS}}^{2+}$ molecule. We identify sequential breakup using a uniform distribution as a function of the angle between the conjugate momenta, associated with the first and second fragmentation steps, which is due to the rotation of the intermediate molecule in the fragmentation plane. By exploiting this uniform distribution, we separate the sequential and concerted distributions in any plot created from the measured momenta.