Although neutral 163 Dy is a stable isotope, the fully ionized 163 Dy 66 + undergoes ? decay into the K and L shells with a half-life of 47 days.
After the electron has been ejected, the atom is left with a vacant energy level, also known as a L shell to the K shell, the X-ray emitted is called a K-alpha X-ray.
The closest shell to the nucleus is called the " shell " ( also called " K shell " ), followed by the " shell " ( or " L shell " ), then the " shell " ( or " M shell " ), and so on farther and farther from the nucleus.
Indeed, even if the photoelectric effect is the favoured reaction for a particular single-photon bound-electron interaction, the result is also subject to statistical processes and is not guaranteed, albeit the photon has certainly disappeared and a bound electron has been excited ( usually K or L shell electrons at gamma ray energies ).
Therefore, the K shell, which contains only an subshell, can hold up to 2 electrons; the L shell, which contains an and a, can hold up to 2 + 6 = 8 electrons, and so forth; in general, the " n " th shell can hold up to 2 " n " 2 electrons.
The first was that the electron responsible for the brightest spectral line ( K-alpha ) which Moseley was investigating from each element, results from a transition by a single electron between the K and L shells of the atom ( i . e ., from the nearest to the nucleus and the one next farthest out ), with energy quantum numbers corresponding to 1 and 2.