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The investigation of the multiple-ionization and subsequent dissociation of molecules induced by charge particle is one of the most challenging and complex problems in collision physics. In recent times, the breakup dynamics of Coulomb exploded molecular ions has caught a considerable amount of interest among the experimental physicists and chemists. The momentum spectroscopy of dissociating tri- and poly-atomic molecules is very interesting as it throws light on the few body quantum dynamics in these molecular systems. Presently, we have studied the bond breakage dynamics of few simple tri-atomic systems such as CO2 and N2O using a newly built Recoil Ion Momentum Spectrometer (RIMS) setup [1]. We have performed charge particle induced breakup of CO2 and N2O (in this case both fast electrons and highly charged heavy ions) using an ECR based Ion Accelerator (ECRIA) at TIFR. Carbon dioxide has long been used as a prototype system to study the fragmentation dynamics upon the impacts of heavy ions [2], electrons [3], and photons [4]. However, for ion projectiles, the detailed study of fragmentation dynamics of CO2q+ in the intermediate velocity regime is clearly lacking in the literature. Additionally, most of the earlier works mainly concentrated on the decay dynamics of CO23+ or were only limited to the kinetic energy release (KER) distribution studies. In present experiment, we have investigated the three-body breakup dynamics of carbon dioxide molecular ion (CO2q+ where q = 3-5) in collision with 1 au Ar8+ ions [5]. The motivation behind this study is to answer whether the bond breakup in CO2q+ happens in a concerted manner, i.e. one-step, or sequential manner, i.e. two-step, and to gain further insight about these processes. On the other hand, N2O has received much less attention. Further, the ionization and fragmentation dynamics of N2O were mainly investigated in photon [6, 7] and electron [8] impact experiments. Here, we investigate two- and three-body dissociation of multiply charged nitrous oxide molecular ion (N2Oq+, where q ≤ 7) upon the impacts of fast electrons and highly charged heavy ions. Unlike CO2, N2O being an asymmetric molecule, where the two N atoms are not equivalent, it becomes difficult to identify between the central and the terminal N atoms. In order to identify these central and terminal N atoms correctly we have proposed a new analysis method by imposing certain kinematical conditions. Some of these aspects along with the experimental setup will be addressed in the talk.
References
[1] A. Khan et al, Rev. Sci. Instrum. 86, 043105 (2015).
[2] N. Neumann, et al., Phys. Rev. Lett. 104, 103201 (2010).
[3] C. Tian and C. R. Vidal, Phys. Rev. A 58, 3783 (1998).
[4] C. Wu, et al., Phys. Rev. Lett. 110, 103601 (2013).
[5] A. Khan, et al., Phys. Rev. A 92, 030701(R) (2015).
[6] M. Alagia et al, Chem. Phys. Lett. 432, 398 (2006).
[7] R. Karimi et al, J. Chem. Phys. 138, 204311 (2013).
[8] A. Khan and D. Misra J. Phys. B: At. Mol. Opt. Phys. 49, 055201 (2016). |