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

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

Effect of ampoule support on the growth of organic benzimidazole single crystals by vertical Bridgman technique for nonlinear optical applications

Benzimidazole single crystals were grown using a vertical Bridgman technique with modified ampoule design. The thermal fluctuations during the melt were effectively controlled by the glass ampoule support which was filled with alumina wool in order to maintain a proper temperature gradient throughout the growth process. The unit cell dimensions of the grown crystals were assessed using powder X-ray diffraction technique. Comparative analyses have been carried out for both the crystals which were grown using a conventional ampoule and using the ampoule with support, via high resolution X-ray diffraction and it was found that there was a significant enhancement in crystalline perfection for the crystal which was grown using the ampoule with support. Further, optical transmission and photoluminescence studies on the grown crystals were carried out using UV-vis and photoluminescence spectroscopy and it was observed that there was a noticeable variation in the optical transmission and luminescence results

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

Radiobiological effectiveness of iodouracil and the influence of atomic giant resonance

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; EspañaFil: Chowdhury, Madhusree Roy. International Centre of Theoretical Science. Tata Institute of Fundamental Research; EspañaFil: Bagdia, Chandan. 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: Weck, Philippe F.. Sandia National Laboratories; Estados UnidosFil: Tribedi, Lokesh C.. International Centre of Theoretical Science. Tata Institute of Fundamental Research; Españ

Double differential distribution of electron emission in the ionization of water molecules by fast bare oxygen ions

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