Fragmentation dynamics of diatomic molecules under proton impact: Kinetic energy release spectra of CO^{q+} and NO^{q+} (q = 2, 3) molecular ions

We report on the fragmentation dynamics of triply charged, diatomic, molecular ions of NO and CO. Dissociative fragmentation after multiple ionization of NO and CO is studied under the impact of 200 keV proton beam using recoil-ion momentum spectrometer. Kinetic Energy Release distributions (KERDs) for various fragmentation channels were obtained. We have also calculated the potential energy curves (PECs) for ground and several excited states of NO^{3+} and CO^{3+} molecular ion. The obtained KERDs are discussed in the background of the calculated PECs as well as the simple Coulomb excitation model. Coulomb breakup of the unstable precursor molecular ion shows a clear preference for the N^{2+} + O^+ (and C^{2+} + O^+) fragmentation channel.Comment: 8 pages, 6 figures, 3 table

Electron emission from fluorene molecule in collisions with 3.5 MeV/u Si8+^{8+} ions

We present measured absolute double differential cross section (DDCS) of electron emission from fluorene (C13H10) molecule upon 3.5 MeV/u Si8+ ion impact. We have compared the energy and angular distributions of the DDCS with CB1 (Ist Born with correct boundary conditions) calculations. The e-DDCS shows an indication of collective excitation peak in low energy part of the spectrum at a few backward angles. The shape of the distribution has also been compared with that for a smaller molecule i.e. CH4

Bare-carbon-ion-impact electron emission from adenine molecules: Differential and total cross-section measurements

Double-differential ionization cross sections (DDCS) for bare-carbon-ion-induced ionization of vapor-phase adenine molecules (C5H5N5) have been measured. The experiment has been performed using an electron spectroscopy technique. Electrons ejected from adenine were analyzed by a hemispherical electrostatic deflection analyzer over an energy range of 1-450eV for emission angles from 20 to 160. The single-differential cross section (SDCS) and total ionization cross section were also deduced. The experimental results have been compared with the continuum distorted wave-eikonal initial-state model calculation. We have observed a very good agreement between the theory and experiment. The angular distribution of the DDCS, SDCS and the asymmetry parameter for low-energy (Ee≤0.5 a.u.) electron display an oscillatory behavior which is in contrast to that observed in ion-atom collisions. A comparison is also made with available experimental cross-section results for uracil target colliding with the same velocity bare carbon ions and the scalability of ionization cross sections among these molecules is discussed.Fil: Bhattacharjee, Shamik. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; EspañaFil: Bagdia, Chandan. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; EspañaFil: Chowdhury, Madhusree Roy. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; EspañaFil: Mandal, Anuvab. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; EspañaFil: Monti, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Rivarola, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Tribedi, Lokesh C.. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; Españ

Electron emissions from

We have studied the electron emissions from the smallest hydrocarbon molecule, $$\hbox {CH}_4$$, in collisions with 94 MeV $$\hbox {Si}^{13+}$$-ions. The absolute double differential cross sections (DDCS) of electron emissions are measured in the energy range of 3–400 eV and in the angular range 20$$^{\circ }$$ to 160$$^{\circ }$$ The measured data have been compared with the continuum distorted wave-eikonal initial state (CDW-EIS) model. The CDW-EIS calculations performed with the complete neglect of differential overlap (CNDO) and the molecular orbital (MO) description of the target are presented. Calculations using both target descriptions show a reasonably good agreement with the measured data. However, the CDW-EIS (MO) shows better agreement with the measured cross sections as compared to the CDW-EIS (CNDO). The single differential cross section, total cross sections have also been deduced from the measured DDCS. The KLL Auger hypersatellite peak due to the double K-vacancy in C-atom has been observed. The ratio of double-to-single K-vacancy production cross section is found to be substantially large, i.e., 33%. The present data, obtained by using such highly charged ions, provides crucial input to the applicability of this MO-based CDW-EIS model for such collisions

Energy and angular distribution of electrons ejected from water by the impact of fast O8+ ion beams

Abstract: Double differential cross sections (DDCS) of electrons emitted from vapor water molecules (in vapor phase) by 2.0 MeV/u and 3.75 MeV/u bare oxygen ion impact have been measured by continuum electron spectroscopy technique. The ejected electrons were detected by an electrostatic hemispherical deflection analyzer over an energy range of 1–600 eV and emission angles from 20∘ to 160∘. The DDCS data has been compared with the continuum-distorted-wave-eikonal-initial state (CDW-EIS) approximation and a reasonable agreement was found with both version of the models i.e. post and prior version. By numerical integration of the DDCS data, the single differential cross section (SDCS) and total ionization cross section (TCS) were obtained. The obtained TCS results were compared with other available TCS results for water target within the same energy range. The total ionization cross sections values are seen to saturate as the projectile charge state (qp) increases, which is in contrast to the first-Born predicted qp 2 dependence. This is also in contrast to the prediction of the CDW-EIS models.Fil: Bhattacharjee, Shamik. Tata Institute of Fundamental Research; IndiaFil: Bagdia, Chandan. Tata Institute of Fundamental Research; IndiaFil: Chowdhury, Madhusree Roy. Tata Institute of Fundamental Research; IndiaFil: Monti, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Rivarola, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Tribedi, Lokesh C.. Tata Institute of Fundamental Research; Indi

Electron emission in ionization of adenine molecule induced by 5 MeV/u bare C ions

The double differential cross sections (DDCS) of electron emission in ionization of adenine molecule (C5H5N5) induced by 5 MeV/u bare C ions are measured using the electron spectroscopy technique. Emission of electrons from adenine is measured in the energy range from 20 eV to 460 eV and in the angular range from 20° to 160°. The single differential cross sections (SDCS) and total ionization cross section (TCS) are deduced from the e-DDCS. The experimental results are compared with the prior form of the continuum distorted wave- eikonal initial state (CDW-EIS) model prediction. Overall, a very good agreement between the theory and experiment is observed

Electron emission from CH4 molecules in collisions with fast bare C ions

We present the energy and angular distributions of electron emission from a CH4 molecule in collisions with fast bare C ions with energies 3.5 and 5.5 MeV/u. The absolute double differential cross sections (DDCS) are measured for the ejected electrons having energies from 11 eV to 330 eV for 3.5-MeV/u projectiles and from 5 eV to 330 eV for 5.5 MeV/u bare C ions. The emission is measured in the angular range from 20∘ to 160∘. The forward-backward angular asymmetry, the single differential cross sections (SDCS), and the total cross section are deduced from the measured DDCS values. The energy and angular distributions of the DDCS and SDCS are compared with those calculated using a theoretical model based on the prior form of the continuum distorted wave-eikonal initial state (CDW-EIS) approximation. The dynamics of the process is considered within the CDW-EIS approximation, while the initial orbitals of the molecular target are represented using the complete neglect of the differential overlap approximation. The calculations are found to be in very good agreement with the measured cross sections. The angle dependence of the carbon K-LL Auger emission and the total Auger emission cross section are also derived for both projectile energies.Fil: Mandal, Anuvab. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Bagdia, Chandan. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Roy Chowdhury, Madhusree. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Bhattacharjee, Shamik. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Misra, Deepankar. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Monti, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Rivarola, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Tribedi, Lokesh C.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; Españ

Ionization of atoms and molecules using 200-keV protons and 5.5-MeV/u bare C ions: Energy-dependent collision dynamics

Using electron spectroscopy technique, we measure the absolute double-differential cross sections (DDCSs) of electrons emitted in collisions of 200-keV protons on He, CH4, and O2 and 5.5-MeV/u bare C ions colliding on O2. The emitted electrons are measured in the energy range from 1 to 400 eV for He and CH4 targets and up to 600 eV for O2 to include the K-LL Auger line of oxygen. The electrons are detected over different emission angles varying from 20∘ in the extreme forward direction to 160∘ in the backward direction. The single-differential cross section (SDCS) and total cross section are deduced from the measured DDCSs spectra for all the targets. The DDCS and SDCS are compared with the state-of-the-art continuum distorted wave-eikonal initial state (CDW-EIS) theoretical model. The CDW-EIS model provides excellent agreement with the oxygen data at MeV energy, whereas the deviation in the case of keV energy is substantial, in spite of having nearly the same perturbation strength. The forward-backward angular asymmetry shows a saturation effect in the case of keV energy protons but no such signature is observed for the high-energy collision. A systematic analysis reveals that the asymmetry at low electron energy is sensitive to the associated atomic or molecular structure and is in close agreement with the theory.Fil: Roy Chowdhury, Madhusree. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Mandal, A.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Bhogale, A.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Bansal, H.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Bagdia, C.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Bhattacharjee, S.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Monti, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Rivarola, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Tribedi, Lokesh C.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; Españ