Cross sections for electron-impact excitation of krypton from the levels of 4p6, 4p55s, and 4p55p configurations

The electron-impact excitation cross sections at low electron energies have been calculated using a fully relativistic R-matrix method for transitions between levels of 4p6, 4p55s, and 4p55p configurations. To ensure the convergence of results, we have paid special attention to the factors that may affect the convergence of cross sections. For examples, we have included extensive configuration interactions in the wave-function expansion of the target states. A large enough R-matrix boundary has been taken to ensure the convergence of atomic wave functions. Contributions to cross sections from a large number of partial waves (up to J=39.5) have been explicitly calculated. The final results are in good agreement with recent experimental data by Jung et al. [Phys. Rev. Lett. 94, 163202 (2005)] after shifting the position of electron energy. The relative difference is about 10% for four transitions out of the metastable levels. The results eliminated the significant discrepancies between theory and experimental work on excitation cross sections out of the metastable levels reported in the literature