Nuclear excitation by two-photon electron transition

TL;DR

This paper introduces a theoretical mechanism where two-photon electron transitions can excite nuclei, with calculations showing comparable probabilities to existing methods, opening new avenues for nuclear excitation studies.

Contribution

The paper proposes and analyzes a novel nuclear excitation mechanism via two-photon electron transitions, supported by detailed calculations for specific ions.

Findings

Probability of nuclear excitation via NETP is 3.5 x 10^-9.

NETP probability is comparable to other nuclear excitation mechanisms.

Feasibility of experimental observation is discussed.

Abstract

A new mechanism of nuclear excitation via two-photon electron transitions (NETP) is proposed and studied theoretically. As a generic example, detailed calculations are performed for the $E1E1$ $1s2s\,^1S_0 \rightarrow 1s^2\,^1S_0$ two-photon decay of He-like $^{225}$Ac$^{87+}$ ion with the resonant excitation of the $3/2+$ nuclear state with the energy 40.09(5) keV. The probability for such a two-photon decay via the nuclear excitation is found to be $P_{\rm NETP} = 3.5 \times 10^{-9}$ and, thus, is comparable with other mechanisms, such as nuclear excitation by electron transition and by electron capture. The possibility for the experimental observation of the proposed mechanism is thoroughly discussed.