Electron emission in fast heavy ion impact ionization of C 60 and Ne: giant plasmon excitation
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THE EUROPEAN PHYSICAL JOURNAL D
Regular Article
Electron emission in fast heavy ion impact ionization of C60 and Ne: giant plasmon excitation? A.H. Kelkar1 , D. Misra2 , L. Guly´ as3 , and Lokesh C. Tribedi2,a 1 2 3
Indian Institute of Technology Kanpur, Kanpur 208016, India Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Colaba, Mumbai 400005, India Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), Debrecen H-4001, Hungary Received 5 March 2020 / Received in final form 26 May 2020 Published online 23 July 2020 c EDP Sciences / Societ`
a Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020 Abstract. We have measured the energy and angle differential ejected electron spectra of C60 as well as Ne atoms in collisions with 4 MeV/u bare fluorine projectile ions. Absolute cross sections have been estimated for electron emission in the energy range of 1 eV–300 eV, including the KLL-Auger electrons for various angles between 30◦ and 150◦ . The double differential cross sections for C60 have been compared with the state-of-the-art CDW-EIS model under CNDO approximation as well as with the data for the Ne target. The C60 spectra at all angles show a broad giant plasmon resonance in the low energy region, which is not present in the atomic target data. The angular distribution reveals the dipolar nature of the plasmon excitation. The C K-LL Auger emission from C60 reveals a large angular anisotropy compared to that for a hydrocarbon, e.g. methane target.
1 Introduction Ejected electron emission from atomic and molecular targets upon external perturbation gives a detailed insight into the dynamics of electromagnetic interaction. Over the years, electron spectroscopy has been established as a powerful technique providing rich information on the energy spectrum and angular distribution of the ejected electrons. Energy and angle-dependent electron emission cross sections or DDCS (double differential cross sections) have been measured for a variety of atomic and molecular targets. Theoretical models have closely followed the advancements in experimental measurements. For example, the collisions with photons are very well described by the closed coupling scattering theory and a R-matrix calculation [1]. The e-emission dynamics in the highly charged heavy ion interaction, on the other hand, need a two center approach to explain the evolution of the final state wave-function. A state-of-the-art quantum mechanical model based on the continuum distorted waveeikonal initial state (CDW-EIS) approximation [2,3] and different versions of it have been shown to reproduce quite well the observed energy and angular-distributions of the electron DDCS for small to large atomic and molecular targets, such as, H, He, H2 , O2 , N2 , H2 O, uracil adenine ?
Contribution to the Topical Issue “Atomic Cluster Collisions (2019)”, edited by Alexei Verkhovtsev, Pablo de Vera, Nigel J. Mason, Andrey V. Solov’yov. a e-mail: [email protected]
etc. [4–8] under fast ion-collisions. The t
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