• Rajesh Srivastava

      Articles written in Pramana – Journal of Physics

    • Excitation of 31,3P and 31,3D states of helium from the ground 11S state by electrons and positrons

      Surbhi Verma Rajesh Srivastava

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      A systematic theoretical study is carried out for the electron and positron impact excitation of the 31,3P and 31,3D states of helium from the ground 11S state. The results are reported for the differential cross sections, Stokes parameters and alignment and orientation parameters. To calculate the scattering amplitude which relate these parameters, a distorted wave approximation theory with different choices of distortion potential has been used. The results are compared with available theoretical and experimental data in the energy range of 40–100eV.

    • Electron-photon coincidence studies on electron impact excitation of lighter neutral atoms

      Rajesh Srivastava

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      Recently we applied non-relativistic distorted wave approximation theory to study electron impact excitations in lighter atoms (viz. hydrogen, helium and some alkalis). Excitations from the ground and (or) initially excited metastableS states to next upper excitedP andD states have been considered. Results for the differential cross-sections and electron-photon coincidence parameters are obtained. Here the theory and the calculation of various scattering parameters are described briefly and some selected results are presented and discussed.

    • Electron impact excitation of theD states of Mg, Ca and Sr atoms: Complete experiment results

      Sachin Saxena Kshamata Muktavat Rajesh Srivastava

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      We have used non-relativistic and relativistic distorted wave approximation methods to study the excitation of then1D states of magnesium (n = 3), calcium (n = 4) and strontium (n = 5) from the ground n1S state. Calculations have been performed for the complete set of parameters (σ,$$\tilde L_ \bot ^ + ,\tilde L_ \bot ^ - ,\tilde \gamma ^ + ,\tilde \gamma ^ - $$). The results are presented for electron impact energies of 20 and 40 eV. We compare our results obtained from both the non-relativistic and relativistic methods with each other. Good agreement is found on comparison and the importance of relativistic effects is also explored.

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