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We report the development and performance of a cold target recoil ion momentum spectrometer (COLTRIMS) setup at TIFR, which is built to study various atomic and molecular processes involving the interaction of slow, highly charged ions from an electron cyclotron resonance based ion accelerator. We give a detailed description of the experimental setup, as well as report some initial results on the electron-capture process in collisions of Ar8+ ions with helium and carbon monoxide targets. Here, we present the longitudinal momentum transfer and the sub-shell resolved Q-value spectrum in the case of 2, 4, and 6 keV/u Ar8+ beams in collision with helium. A longitudinal momentum resolution of 0.27 a.u. is achieved in the present system. We also report the state-selective scattering angle distributions for all the collision systems under investigation. We further discuss the fragmentation of the CO2+ molecular ions for different electron capture channels for the 5 keV/u Ar8+ beam. The combination of the COLTRIMS, along with the beam cleaner, the electrostatic deflectors, and the charge state analyzer, is shown to have certain advantages.

The development of a recoil ion momentum spectrometer (RIMS) along with a post-collision projectile charge state analyzer (CSA) and its performance for carrying out studies of molecular fragmentation following direct ionization, electron-capture, and capture-ionization have been demonstrated here. This is a two-stage Wiley-McLaren type spectrometer with slight modification introduced by adding a lens to achieve higher momentum resolution as well as larger angular acceptance. Along with the time and position sensitive detector, it can measure all the three momentum components of singly charged recoil ions of energy up to 10 eV emitted in all directions. The CSA assembly is designed for separating out any neutral or singly or doubly charged post-collision projectiles typically of keV energy. The RIMS with initial trigger ("start") from CSA or an ionized electron can uniquely determine the dynamics of molecular fragmentation following different electron-capture or direct ionization events, respectively. To check the performance of the setup, we carried out an experimental study of the fragmentation of N

1s-1s electron transfer and K-shell ionization cross sections of adenine (C5H5N5) molecule have been measured in collisions with C and O ions in the energy range of 2.5–5.3 MeV/u. These cross sections have been measured from the study of KLL Auger electron yields as a function of projectile charge state. The K-ionization cross section data have been compared with the ECUSAR calculations [ECPSSR model with the perturbed stationary state (PSS) effect calculated in a united and separated atom (USA) approximation]. The K-ionization data shows a good agreement with the model whereas the K-K transfer cross section is underestimated by the same model. Energy dependence of the K-K transfer cross section for adenine is found to be flat compared to that for N2 gas molecules. The values of the K-K e− transfer and the K-ionization cross sections are found to be comparable in this energy range.

We have investigated the ionization and fragmentation of a polycyclic aromatic hydrocarbon molecule, fluorene ( $$\hbox {C}_{{13}}\,\hbox {H}_{{10}}$$ ), upon proton impact with energy 250 keV. Various ionization and fragmentation products have been identified. Hydrogen-loss process from singly and doubly ionized parent molecules has been found to be a dominating channel. In case of singly ionized molecule, up to three H-losses have been observed. However, two H-loss ion has not been observed. For the doubly ionized molecule up to four H-losses have been observed. The ratio of doubly to singly charged parent ions are found to be quite high compared to the atomic targets, such as, He and Ne.

Hadron therapy combined with nanotechnology has been proposed as an elegant alternative for cancer treatment. Internal amplification of electron emission causing radiobiological effectiveness in nanoinserted biomolecules is of prime importance and has been measured here for the iodouracil molecule. Our experiment involves the measurement of angle and energy resolved double differential cross section (DDCS) of electron emission from iodouraciil and uracil (and also water) in collisions with fast C6+ ions. The electron emission from iodouracil is substantially enhanced over that from uracil or water. The enhancement is much larger than the state-of-the-art model for Coulomb ionization based on the continuum distorted wave-eikonal initial state (CDW-EIS) approximation. The electron sensitizing factor (˜2.4) is in excellent agreement with the strand-breaking sensitizing factor (˜2.0) for metal nanoparticle embedded in a DNA. The enhancement is explained in terms of collective excitation of strongly correlated 4d electrons, known as atomic giant dipole resonance (GDR) in I atoms. The GDR contribution to the enhancement is derived, which is in excellent agreement with recent theoretical prediction, thereby providing conclusive experimental evidence of the crucial role of collective excitation in radio sensitization. Fil: Mandal, Anuvab. International Centre of Theoretical Science. Tata Institute of Fundamental Research; España Fil: Chowdhury, Madhusree Roy. International Centre of Theoretical Science. Tata Institute of Fundamental Research; España Fil: Bagdia, Chandan. International Centre of Theoretical Science. Tata Institute of Fundamental Research; España Fil: 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; Argentina Fil: 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; Argentina Fil: Weck, Philippe F.. Sandia National Laboratories; Estados Unidos Fil: Tribedi, Lokesh C.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; España

The slowest reaction in the CNO cycle $^{14}\mathrm{N}(p,\ensuremath{\gamma})^{15}\mathrm{O}$ has been studied by populating the ${E}_{p}^{\mathrm{lab}}=278$ keV (${E}_{\mathrm{c}.\mathrm{m}.}^{r}=259$ keV) proton capture resonant state of $^{15}\mathrm{O}$ at 7556 keV. The strength of the resonance ($\ensuremath{\omega}\ensuremath{\gamma}$) has been determined from the experimental data. The level lifetime of the subthreshold resonant state at ${E}_{x}=6792$ keV, as well as the lifetimes of the 5181 keV and 6172 keV states, have been measured using the Doppler shift attenuation method (DSAM). The structural properties of the nucleus $^{15}\mathrm{O}$, such as the level energies, transition strengths, level lifetimes, and spectroscopic factors, have been calculated theoretically by using the large basis shell model, which agrees reasonably well with the present as well as the previous experimental data.

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; España Fil: Mandal, A.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; España Fil: Bhogale, A.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; España Fil: Bansal, H.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; España Fil: Bagdia, C.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; España Fil: Bhattacharjee, S.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; España Fil: 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; Argentina Fil: 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; Argentina Fil: Tribedi, Lokesh C.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; España

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.

Pure and different support gas-mixed krypton plasmas are produced using the 14.5 GHz all permanent-magnet based electron cyclotron resonance (ECR) ion source. The ions are extracted and the charge state distributions (CSDs) are studied. The H2, He, N2, O2, Ne, Ar, CH4 and CO2 gases are used as support gases. One of the support gases are mixed with Kr at several mixing ratios and its effect on the outputs currents of the Kr ions are studied. The total effective charge, as well as effective charges of Kr and mixing gas ions are calculated from the measured ion currents. The total ion loss rates are also calculated. The gases N2, O2, Ar and CO2 are found to exhibit better mixing effect in the enhancement of output of highly charged ions. The best enhancement in the output currents of Kr ions is observed in case of O2 as the mixing gas under certain conditions. To the best of our knowledge such a detail comparative study on the influence of mixing gas has not been reported so far for ECR ion-beam application.

The cross sections for production of Mk (k = Mξ, Mαβ, Mγ, Mm1) X-rays of 70Yb, 81Tl and 82Pb induced by 50–250 keV protons have been measured in the present work. The experimental cross sections have been compared with the earlier reported values and those calculated using the ionization cross sections based on the ECPSSR (Perturbed (P) stationary(S) state(S), incident ion energy (E) loss, Coulomb (C) deflection and relativistic (R) correction) model, the X-ray emission rates based on the Dirac-Fock model, the fluorescence and Coster-Kronig yields based on the Dirac-Hartree-Slater (DHS) model. In addition, the present measured proton induced X-ray production cross sections have also been compared with those calculated using the Dirac-Hartree-Slater (DHS) model based ionization cross sections and those based on the Plane wave Born Approximation (PWBA). The measured M X-ray production cross sections are, in general, found to be higher than the ECPSSR and DHS model based values and lower than the PWBA model based cross sections.

The cross sections for production of the Mk (k = ξ, αβ, γ, m1) X-rays of 79Au, 82Pb and 83Bi induced by the 100 keV/u proton, C4+, N5+ and O6+ ions have been measured in the present work. The experimental cross sections have been compared with the earlier reported values and those calculated using the ionization cross sections based on the ECPSSR model, the X-ray emission rates based on the Dirac-Fock model, the fluorescence and Coster-Kronig yields based on the Dirac-Hartree-Slater model. In addition, the present measured proton induced X-ray production cross sections have also been compared with those calculated using the Dirac-Hartree-Slater model based ionization cross sections. The intensity ratios among the Mk X-rays have been deduced and compared with the theoretical values. The present measured Mk (k = ξ, αβ, γ, m1) X-ray production cross sections are found to be very high as compared to the theoretical values. The total M X-ray production cross sections for the targets under investigation exhibited Z p 2 dependence; Zp denotes the projectile atomic number.

An implanted target (14N on Ta) is prepared and characterized via surface and bulk characterization processes. The depth profile of the implanted ions is obtained experimentally by populating a narrow resonance state of15O through14N(ρ,γ) reaction induced with a laboratory proton energy of 278 keV. The experimental profile is then compared with devoted simulations to under- stand the locations of the implantated ions in the lattice structure. Later, the lifetimes of a few excited states of15O, relevant for applications in astrophys- ical scenario, have been determined using Doppler Shift Attenuation Method(DSAM).

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; España Fil: Bagdia, Chandan. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; España Fil: Chowdhury, Madhusree Roy. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; España Fil: Mandal, Anuvab. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; España Fil: 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; Argentina Fil: 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; Argentina Fil: Tribedi, Lokesh C.. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; España

Magnetoimpedance (MI) effect was studied on amorphous Co 33 Fe 33 Ni 7 Si 7 B 20 ribbons that were irradiated with N +1 , Ar +2 and Xe +5 ions, at energy of 75 keV. The (MI) m [maximum MI in each case] values are 9.4% and 11%, 9.9% and 6.5%, the largest, for the as-quenched and N +1 , Ar +2 and Xe +5 ion irradiated ribbons respectively, at 2 MHz. The (MI) m value of the N +1 ion irradiated ribbon was observed to be the highest, due to an induced in-plane transverse magnetic anisotropy. The saturation magnetizations of the ion-irradiated ribbons are not seen to change with respect to that of the as-quenched ribbon; a small increase in the M s was observed only upon irradiation with Xe 5+ ions. The interaction between the large number of domains, with large uniaxial anisotropy led to large (MI) m values, at frequencies above 8 MHz in the Ar +2 ion irradiated ribbon.

We report the measurement of the absolute double differential cross sections (DDCS) of secondary electrons emitted due to the ionization of N2 molecule in collisions with fast electrons having energies between 3 and 5 keV. The emitted electrons with energies from 1–500 eV have been measured for different forward and backward emission angles. The measured DDCS have been compared with the state-of-the-art first Born approximation with correct boundary condition (CB1) model calculations as well as with the classical trajectory Monte Carlo (CTMC) method. From the measured DDCS, the single differential cross sections (SDCS) as a function of the emission energies have been computed and eventually the total ionization cross sections (TCS) have been derived. The TCS values are also compared with a semi-empirical calculation, namely, the CSP-ic (complex scattering potential-ionization contribution) model.

An electrically cooled Broad Energy Germanium (BEGe) detector has been characterized in the energy range E γ ∼ 0 . 122 - 7 MeV by utilizing the γ -rays emitted by a short-lived resonance state in 15O populated through 14N(p, γ ) reaction and standard radioactive source (152Eu). The experimental results have been reproduced through simulations with GEANT4 code, including vendor specified detector geometry along with the detailed construction of the target holder flange, to delineate the effects of the holder at various energies and detector position. Later the efficiency with a bare point source has been simulated. It has been found that the electrically cooled BEGe detector is suitable for usage in the γ -ray spectroscopy as well as for the study of resonance phenomena in nuclear astrophysics.

We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. Roadmap III focusses on heavy particles: with zero to relativistic speeds. Modern theoretical and experimental approaches provide detailed insight into the wide range of many-body interactions involving projectiles and targets of varying complexity ranging from simple atoms, through molecules and clusters, complex biomolecules and nanoparticles to surfaces and crystals. These developments have been driven by technological progress and future developments will expand the horizon of the systems that can be studied. This Roadmap aims at looking back along the road, explaining the evolution of the field, and looking forward, collecting nineteen contributions from leading scientists in the field., Journal of Physics B: Atomic, Molecular and Optical Physics, 52 (17), ISSN:1361-6455, ISSN:0368-3508, ISSN:0953-4075, ISSN:0022-3700

M X-ray yields of thin targets of 79Au and 83Bi in collisions with 50–300 keV protons have been measured. The production cross sections of Mζ[(M5–N3) + (M4–N2)], Mαβ[(M5–N6,7) + (M5–O3) + (M4–N6) + (M4–O2,3) + (M3–N2)], Mγ[(M3–N4,5) + (M2–N1)], Mm1[(M3–O1,4,5) + (M2–N4) + (M1–N2,3)] transitions and the total X-ray production cross-section are determined and compared to other available experimental values and also to those obtained from predictions of the PWBA and the ECPSSR models. The intensity ratios of the transitions are compared with the values calculated from the ECPSSR model. All existing experimental to theoretical ratios of the cross-sections as plotted as a function of the reduced velocity show a universal behaviour.

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; India Fil: Bagdia, Chandan. Tata Institute of Fundamental Research; India Fil: Chowdhury, Madhusree Roy. Tata Institute of Fundamental Research; India Fil: 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; Argentina Fil: 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; Argentina Fil: Tribedi, Lokesh C.. Tata Institute of Fundamental Research; India

Low energy nitrogen ions are used in this work to manipulate wetting properties of the surface of the array of Cu2O nano-columns, which yields remarkable results. The nano-columnar thin films were grown on a highly conductive silicon surface by a sputter deposition technique. The films were irradiated at two different fluences of 5 × 10(15) and 1 × 10(16) ions per cm(2), respectively. With increasing fluence the shape of column tip changes, columns are bent and porous channels between columns are clogged up. While the surface of the pristine sample is hydrophilic, the irradiated surface turns into hydrophobic but having adhesion properties. We have analysed the structural and chemical properties of the surface in detail to understand the initial and modified wetting properties. Furthermore, the temporal evolutions of different droplet parameters are investigated to realize the interactions between the water droplet, the sample surface and the atmosphere. We envisage that such modified surfaces can be beneficial for transport of a small volume of liquids with minimum loss and spectroscopic studies, where a small amount of water droplet is available for measurements.

Interaction between polycyclic aromatic hydrocarbon (PAH) molecule and energetic ion is a subject of interest in different areas of modern physics. Here, we present measurements of energy and angular distributions of absolute double differential electron emission cross section for coronene (C24H12) and fluorene (C13H10) molecules under fast bare oxygen ion impact. For coronene, the angular distributions of the low energy electrons are quite different from that of simpler targets like Ne or CH4, which is not the case for fluorene. The behaviour of the higher electron energy distributions for both the targets are similar to that for simple targets. In case of coronene, a clear signature of plasmon resonance is observed in the analysis of forward-backward angular asymmetry of low energy electron emission. For fluorene, such signature is not identified probably due to lower oscillator strength of plasmon compared to the coronene. The theoretical calculation based on the first-order Born approximation with correct boundary conditions (CB1), in general, reproduced the experimental observations qualitatively, for both the molecules, except in the low energy region for coronene, which again indicates the role of collective excitation. Single differential and total cross sections are also deduced. An overall comparative study is presented.

Double-differential cross section (DDCS) for electrons ejected in collisions of fast ${\mathrm{C}}^{6+}$ and ${\mathrm{Si}}^{13+}$ projectiles, with a ${\mathrm{H}}_{2}\mathrm{O}$ vapor target, were measured. The electrons were detected over an energy range of 1--600 eV and an angular range of ${20}^{\ensuremath{\circ}}$--${160}^{\ensuremath{\circ}}$. The obtained DDCS spectra, for both the ions, were compared with the CDW-EIS model. Occasional reference has been made to the DDCS data for the case of 3.75-MeV/u ${\mathrm{O}}^{8+}$ colliding on the same molecule for an overall comparison. A reasonable agreement with theoretical results was seen for the case of ${\mathrm{C}}^{6+}$ and ${\mathrm{O}}^{8+}$ projectiles. However, between ${\mathrm{C}}^{6+}$ and ${\mathrm{O}}^{8+}$ projectiles, the deviation from theory is larger for the case of the carbon projectile. Substantial deviation starts to show up for the case of the ${\mathrm{Si}}^{13+}$ projectile. By numerical integration of the DDCS data, the single-differential cross section (SDCS) and total cross section (TCS) were obtained and compared with theoretical models. The present TCS data along with the other available data for $p$, $\mathrm{He}$, and $\mathrm{C}$ ions were plotted together. A clear and gradual deviation from the Bethe-Born predicted ${q}^{2}$ scaling was observed, where $q$ is the projectile charge state. From all the data we find TCS varies as ${q}^{n}$ where $n$ = 1.7 $\ifmmode\pm\else\textpm\fi{}$ 0.1. The provided data set will be valuable in order to help model the radiation damage in hadron therapy, particularly in the Bragg peak region.

Absolute double differential cross sections (DDCS) of secondary electrons emitted in ionization of O2 by fast electrons have been measured for different emission angles. Theoretical calculations of atomic DDCS were obtained using the first Born approximation with an asymptotic charge of ZT = 1. The measured molecular DDCS were divided by twice the theoretical atomic DDCS to detect the presence of interference effects which was the aim of the experiment. The experimental to theoretical DDCS ratios showed clear signature of first order interference oscillation for all emission angles. The ratios were fitted by a first order Cohen-Fano type model. The variation of the oscillation amplitudes as a function of the electron emission angle showed a parabolic behaviour which goes through a minimum at 90°. The single differential and total ionization cross sections have also been deduced, besides the KLL Auger cross sections. In order to make a comparative study, we have discussed these results along with our recent experimental data obtained for N2 molecule. Graphical abstract: [Figure not available: see fulltext.]. Fil: Chowdhury, Madhusree Roy. Tata Institute of Fundamental Research; India Fil: Stia, Carlos Raul. 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; Argentina Fil: Tachino, Carmen Alejandra. 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; Argentina Fil: Fojon, Omar Ariel. 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; Argentina Fil: 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; Argentina Fil: Tribedi, Lokesh C.. Tata Institute of Fundamental Research; India

We study multiple ionization and subsequent dissociation of nitrous oxide $({\mathrm{N}}_{2}\mathrm{O})$ in collisions with 1 a.u. ${\mathrm{Ar}}^{8+}$ and ${\mathrm{Xe}}^{15+}$ ions. The experiments are performed by using a recoil ion momentum spectrometer (RIMS) equipped with a position- and time-sensitive detector which allows the measurement of the momenta of fragment ions in coincidence. By measuring the momentum vectors of the recoiling fragment ions various important parameters, such as kinetic energy release and those related to molecular structure prior to fragmentation, have been derived. Furthermore, the projectile-charge-state dependence of the fragmentation dynamics of ${\mathrm{N}}_{2}\mathrm{O}$ is investigated and a very mild dependence has been noticed in a few channels. In addition, we also study the concerted and sequential mechanisms in the three-body decay of ${\mathrm{N}}_{2}{\mathrm{O}}^{q+}$ (where $q\phantom{\rule{4pt}{0ex}}\ensuremath{\le}7)$. It has been observed that ${\mathrm{N}}_{2}{\mathrm{O}}^{q+}$ breaks up mainly in a concerted manner except for the ${\mathrm{N}}_{2}{\mathrm{O}}^{3+}\ensuremath{\rightarrow}{\mathrm{N}}^{+}+{\mathrm{N}}^{+}+{\mathrm{O}}^{+}$ (1,1,1) and ${\mathrm{N}}_{2}{\mathrm{O}}^{4+}\ensuremath{\rightarrow}{\mathrm{N}}^{2+}+{\mathrm{N}}^{+}+{\mathrm{O}}^{+}$ (2,1,1) channels. For both these channels, the presence of an intermediate rotating ${\mathrm{NO}}^{2+}$ has been identified. Furthermore, by using Dalitz plot analysis, we have been able to separate various mutually mixed channels of highly charged ${\mathrm{N}}_{2}{\mathrm{O}}^{q+}$.

Synopsis We present the experimental and theoretical study of electron emission from methane (CH4) in collisions with 5.5 MeV/u bare carbon projectiles. We have measured double differential cross section of electron emission and compared the data with the prior form of the continuum distorted wave – eikonal initial state (CDW-EIS) model calculation. The CDW-EIS calculations are in very good agreement with the data.

Single phase TiO 2 nanostructures are fabricated by oxygen ion implantation (60 keV) at fluence ranging from 1×10 16 ions/cm 2 to 1×10 17 ions/cm 2 in titanium thin films deposited on fused silica substrate and subsequent thermal annealing in argon atmosphere. GAXRD and Raman spectroscopy study reveals formation of single rutile phases of TiO 2 . Particle size is found to vary from 29 nm to 35 nm, establishing nanostructure formation. Nanostructure formation is also confirmed by the quantum confinement effect manifested by the blueshift of the UV–vis absorption spectra. Photoluminescence spectra show peaks corresponding to TiO 2 rutile phase and reveal the presence of oxygen defects due to implantation. The controlled synthesis of single phase nanostructure is attributed to ion induced defects and post-implantation annealing. It is observed that the size of the nanostructures formed is strongly dependent on the ion fluence.

Absolutedouble differential cross sections (DDCS) of electron emission weremeasured for ionization of N2 by fast electrons with energy 7 keV. Measurements wereperformed for different electron emission angles and energies.Evidence of oscillation due to Young-type interference was observedin the DDCS ratios for all angles. The frequency for large backwardangle is found to be larger compared to that for small forward angle.Consequently, the forward-backward asymmetry parameter reveals theoscillatory structure even more clearly. The oscillations observedfor both experimental-to-heoretical DDCS ratios and forward-backwardasymmetry were well explained by the Cohen-Fano model of interferencein a molecular double slit. A periodic deviation of the Cohen-Fanomodel from the asymmetry parameter data reveals the presence of ahigher-frequency component.The first Born model was employed to explain the results of molecularnitrogen for which a complete-neglect-of-differential-overlapapproximation was used along with an effective atomic number. Fil: Roy Chowdhury, Madhusree. Tata Institute of Fundamental Research; India Fil: Stia, Carlos Raul. 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; Argentina Fil: Tachino, Carmen Alejandra. 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; Argentina Fil: Fojon, Omar Ariel. 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; Argentina Fil: 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; Argentina Fil: Tribedi, Lokesh C.. Tata Institute of Fundamental Research; India

We report the effects of exposing a hydrothermally grown, single crystalline ZnO nanorod array to a beam of 50 keV argon ions at room temperature. High resolution electron microscopy reveals that the ion bombardment results in a nanometer-scale roughening of the nanorod sidewalls, which were almost atomically flat in the pristine sample. Ion bombardment further causes the flat, ≈100 nm diameter nanorod tips to get sharpened to ultrafine points less than 10 nm across. While tip sharpening is attributed to preferential sputtering, the formation of crystalline surface protuberances can be ascribed to surface instability due to curvature dependent sputtering and surface diffusion under argon-ion bombardment. Both the nanoscale roughening as well as the tip sharpening are expected to favorably impact a wide variety of applications, such as those involving catalysis, gas sensing, solar cells, field emission and gas discharge.

We study electron emission from atoms and molecules in collisions with fast electrons and heavy ions (C 6+ ). The soft collision electrons (SE), two center electron emission (TCEE), the binary encounter (BE) events and the KLL Auger lines along with the elastically scattered peaks (in electron collisions) are studied using a hemispherical electrostatic electron analyzer. The details of the measurements along with description of the spectrometer and data acquisition system are given. The angular distributions of the low energy (few eV) electrons in soft collisions and the binary encounter electrons at keV energies are compared with quantum mechanical models based on the first Born (B1) and the continuum distorted wave-Eikonal initial state approximation (CDW-EIS).

The doubly differential distributions of low-energy electron emission in the ionization of water molecules under the impact of fast bare oxygen ions with energy of 48 MeV are measured. The measured data are compared with two quantum-mechanical models, i.e. the post and prior versions of the continuum distorted wave-eikonal initial state (CDW-EIS) approximation, and the first-order Born approximation with initial and final wavefunctions verifying correct boundary conditions (CB1). An overall excellent qualitative agreement is found between the data and the CDW-EIS models whereas the CB1 model showed substantial deviation. However, the detailed angular distributions display some discrepancies with both CDW-EIS models. The single differential and total cross-sections exhibit good agreement with the CDW-EIS models. The present detailed data set could also be used as an input for modeling highly charged ion induced radiation damage in living tissues, whose most abundant component is water. Similar measurements are also carried out for a projectile energy of 60 MeV. However, since the double differential cross-section data show similar results the details are not provided here, except for the total ionization cross-sections results. Fil: Bhattacharjee, Shamik. Tata Institute of Fundamental Research; India Fil: Biswas, Shubhadeep. Tata Institute of Fundamental Research; India Fil: Bagdia, Chandan. Tata Institute of Fundamental Research; India Fil: Roychowdhury, Madhusree. Tata Institute of Fundamental Research; India Fil: Nandi, Saikat. Tata Institute of Fundamental Research; India Fil: Misra, Deepankar. Tata Institute of Fundamental Research; India Fil: 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; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; Argentina Fil: Tachino, Carmen Alejandra. 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; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; Argentina Fil: 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; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; Argentina Fil: Champion, C.. Universite de Bordeaux; Francia Fil: Tribedi, Lokesh C.. Tata Institute of Fundamental Research; India

We have investigated the single and multiple ionizations of the C60 molecule in collisions with fast Siq+ projectiles for various projectile charge states (q) between q = 6 and 14. The q-dependence of the ionization cross sections and their ratios is compared with the giant dipole plasmon resonance (GDPR) model. The excellent qualitative agreement with the model in case of single and double ionizations and also a reasonable agreement with the triple (and to some extent with quadruple) ionization (without evaporation) yields signify dominant contributions of the single-, double- and triple-plasmon excitations on the single- and multiple-ionization process.

We have studied fast ion-atom and electron-atom collision processes using a reconditioned high resolution X-ray spectrometer. The X-rays, generated by the collisions, are dispersed by a curved ADP crystal (Johansson geometry) and detected by a gas proportional counter. A self-written LabVIEW based program has been used to give precise and controlled movement to the crystal and for data acquisition. The performance was tested by detecting the Kα diagram and satellite lines of several elements. The Kα satellite lines of Al have been studied in collision with 3–12 keV electrons and 40 MeV C4+ ions. In ion collisions as large as four L-vacancies are created simultaneously with the K-vacancy, compared to two satellites in case of the e-impact. In addition, we have measured the X-rays from H-, He- and Li-like Si ions which arise due to the electron loss/capture process in highly charged 80 MeV Si7+ ions in collision with thin carbon foil. Approximate charge state distribution has been obtained using this new technique.

We have investigated the effect of Young type interference on the forward backward angular asymmetry in electron emission from molecular hydrogen in collisions with fast bare carbon ions. The asymmetry parameter shows an oscillatory behaviour as a function of electron velocity which is absent in atomic target such as He. It is shown that the asymmetry parameter which is based on DDCS from H2only can be a tool to investigate the Young type interference. The measured energy and angular distributions as well as the asymmetry parameter are compared with a molecular CDW-EIS (continuum distorted wave-eikonal initial state) model.

Single and multiple ionization of C60 in collisions with fast (v = 9.7 a.u.) Oq+ ions have been studied. Relative cross sections for production of C 60 1 + to C 60 4 + have been measured. The intensity ratios of double-to-single ionization agree very well with a model based on giant dipole plasmon resonance (GDPR). Almost linear increasing trend of the yields of single and double ionizations with projectile charge state is well reproduced by the single and double plasmon excitation mechanisms. The observed charge state independence of triple and quadruple ionization is in sharp contrast to the GDPR model.