K‐K electron capture from adenine and CO₂ molecule by fast carbon ions using KLL‐Auger electron technique

Abstract

The experimental measurement of total electron transfer cross section in Bragg peak energy region is important to understand energy loss in the biomolecular system. In this study, we have measured state selective, K‐K electron capture and K‐ionization cross sections for adenine (C 5H 5N 5) in collisions with fast (2.5–5 MeV/u) C ions. These are compared with the data for smaller gas molecule, CO 2. These are derived from a study of the KLL‐Auger electron emission yields as a function projectile charge state. The K‐ionization cross‐section (σKI) data are compared with the ECUSAR (united and separated atom [USA] approximation with energy loss [E], Coulomb deflection [C], and relativistic [R] corrections) model calculation. The measured σKI data and the calculations are in good agreement. The K‐K transfer cross‐section (σK−K) data are compared with the CPSSR (perturbed stationary state [PSS] with Coulomb deflection [C] and relativistic corrections [R]) calculation that underestimates the measured data for such symmetric collision system. The energy dependence of σK−K for adenine is found to be flat in contrast to a sharp variation predicted by the model. The K‐transfer cross section is found to be substantial fraction of the K‐ionization.

Multiple valence electron detachment following Auger decay of inner-shell vacancies in gas-phase DNA

“…MeV ion collisions predominantly lead to emission of valence electrons, and only collisions with very small impact parameters lead to inner shell ionization, as recently shown for 42 MeV C 6+ collisions with the gas-phase adenine nucleobase, where only about 4% of the total ionization cross section where due to K shell ionization. [39][40][41][42] A mass spectrum obtained aer 11.76 MeV C 4+ collisions with (dTGGGGT-2H) 2À is shown in Fig. 3a.…”

Electron emission from fluorene (C13H10) upon 3.5 MeV/u Si8+ ion impact: double differential distributions

“…The normalization factor has been obtained by taking the ratio of total absolute C-KLL Auger cross section for CH 4 to that of relative C-KLL Auger cross section (per carbon atom) for the fluorene molecule. The detailed process for normalization and absolute cross section measurement for vapor jet targets can be found in [34,49].…”