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 subshell to another within the same shell. For instance, an electron could transition from the 2s subshell to the 2p subshell, or vice versa. These transitions are governed by selection rules that dictate which transitions are allowed or forbidden based on changes in quantum numbers, particularly the angular momentum quantum number. While the principal quantum number *n* remains unchanged during an intersubshell transition, the angular momentum quantum number *l* and the magnetic quantum number *m_l* can change. The energy difference between the subshells determines the energy of the absorbed or emitted photon during the transition. Intersubshell transitions are important for understanding atomic spectra and the electronic structure of atoms.