intersubshell
Intersubshell is a term used in atomic physics and spectroscopy to describe transitions of electrons between different subshells within the same electron shell. An electron shell, designated by the principal quantum number *n*, can contain multiple subshells, denoted by the azimuthal quantum number *l*. These subshells are labeled as s, p, d, and f, corresponding to *l* values of 0, 1, 2, and 3, respectively. For example, the second electron shell (*n*=2) has two subshells: the 2s subshell (*l*=0) and the 2p subshell (*l*=1).
An intersubshell transition occurs when an electron absorbs or emits energy, causing it to move from one