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Atomic Physics Group, IIT Roorkee

Indian Institute of Technology, Roorkee

Electron impact excitation of atoms and ions

The Atomic Physics group has been actively engaged in studying electron impact excitation of many-electron atoms/ions using the relativistic distorted wave (RDW) method. In the RDW approximation, the numerical solution for the projectile electron continuum wavefunctions are obtained by assuming that the incident/scattered electron travel under the influence of the static potential of the initial/final state. The required wavefunctions for the bound state of the target ion are described within the multi-configuration Dirac-Fock (MCDF) framework. In addition to Coulomb potential, Breit interaction is also considered for evaluating the scattering amplitude. The RDW method is well known to provide reliable collision parameters from intermediate to high energy range.    

Atomic – structure properties

To address the growing demand for electronic structure data of impurity ions in the current fusion research projects, we have recently been involved in performing detailed calculations for atomic parameters using the relativistic configuration interaction (RCI) method and many-body perturbation theory (MBPT). We have considered several inert gas ions, e.g., Na-like Ar7+, Kr25+ and Xe43+, B-like Xe49+, Ar-like Kr18+ and Xe36+, etc.   

Collisional radiative modeling

Using our calculated collision and atomic parameters for impurity ions, we plan to develop a CR model for fusion plasma soon. Over the last two decades, the Atomic Physics group developed collisional radiative (CR) models to explain several optical emission spectroscopy measurements for low-temperature plasma.


Department of Physics, Indian Institute of Technology (IIT) Roorkee, Roorkee 247667, Uttarakhand, India
Group Website

  • [1] S. Rathi et al., "Zeeman spectroscopy of tellurium", Journal of Quantitative Spectroscopy and Radiative Transfer 309, 108704 (2023). [link to article]
  • [2] S. Rathi and L. Sharma, "Calculations of energy levels, radiative transition parameters, hyperfine structure constants AJBJ Landé gJ factors and isotope shifts for Sc XX using the MCDF-RCI method", Physics Open 16, 100160 (2023). [link to article]
  • [3] S. Rathi and L. Sharma, "Extended Calculations of Atomic Structure Parameters for Na-like Ar, Kr and Xe Ions Using Relativistic MCDHF and MBPT Methods", Atoms 10, 131 (2022). [link to article]
  • [4] A. Gomonai et al., "Electron-Impact Excitation of the λ190.8 nm and λ179.9 nm Intercombination Lines in the Tl+ Ion", Atoms 10, 136 (2022). [link to article]
  • [5] D. Mahato et al., "Study of electron impact elastic scattering from Kr@C60 and Xe@C60 using a fully relativistic approach", Journal of Physics B: Atomic, Molecular and Optical Physics 55, 165201 (2022). [link to article]
  • [6] V. Roman et al., "Electron impact excitation of the Tl+ ion: resonance and cascade transitions", Journal of Physics B: Atomic, Molecular and Optical Physics 55, 165203 (2022). [link to article]
  • [7] P. Malker and L. Sharma, "Electron Impact Excitation of Ge-like Te20+–Cd16+ Ions", Atoms 10, 17 (2022). [link to article]
  • [8] A. Kumar Sahoo and L. Sharma, "Electron Impact Excitation of Extreme Ultra-Violet Transitions in Xe7–Xe10 Ions", Atoms 9, 76 (2021). [link to article]
  • [9] D. Mahato, L. Sharma and R. Srivastava, "Study of electron scattering from CH4+, NH3+, H2O+, NH4+ and H3O+ molecular ions with an analytic static potential approach", The European Physical Journal D 75, 289 (2021). [link to article]
  • [10] D. Mahato, L. Sharma and R. Srivastava, "Fully relativistic study on electron impact elastic scattering from Nq+ (q = 1–3), Na+, Arq+ (q = 1–3, 7–8), and Xeq+ (q = 2–6, 8)", International Journal of Quantum Chemistry 122 (2021). [link to article]


Collisional-Radiative Processes Distorted-Wave Approximations Electron – Ion Collisions Electron – Molecule Collisions Electronic Structure Calculations Theory