Wavelengths of the 4d–4p, 0–1 transitions of X-ray lasers in Ni-like ions with Z ≤ 79

Abstract

X-ray lasers on transitions of Ni-like ions are promising due to their high efficiency and possibility of generating radiation in the “water window” region using compact, laboratory pump sources. The precision wavelength values of laser transitions are necessary to determine the ions in which intense laser radiation in the region of 6.70–6.75 nm is possible, because multilayer mirrors with a high reflection coefficient are designed for this narrow range. In this paper, the energy levels of ions of the Ni-like sequence with the nuclear charge 36 ≤ Z ≤ 79 are calculated by the method of relativistic perturbation theory with a zero-approximation model potential. The wavelengths of the two strongest 4d–4p, 0–1 transitions of X-ray lasers are presented. It is shown that the 3d ⁹ _3/24d _3/2 [J = 0]–3d ⁹ _3/24p _1/2 [J = 1] laser transition with λ = 67.38 Å is possible in Sm³⁴⁺ and the 3d ⁹ _3/24d _3/2 [J = 0]–3d ⁹ _5/24p _3/2 [J = 1] transition with λ = 67.48 Å is possible in Gd³⁶⁺. The calculated results coincide with the known experimental data to within the experimental error.