Photon and free electron photon absorption mechanism equations are given in The Grand Unified Theory of Classical Physics Chapter 4; Bound electron and free electron current density patterns are given in Chapter 1 and Chapter 3, respectively, (

Animation by Miguel Vaca.

The photon in free space comprises a partial two-dimensional covering of a spherical shell by great circle electric (E) field lines and orthogonal great circle magnetic (B) field lines wherein the sphere has the size of the photon wavelength. The photon field lines move as an ensemble at light speed and appear in the sub-light speed laboratory frame as one of linear or right or left-handed circularly polarized E and B fields that vary harmonically in time and space over the period corresponding to the wavelength as the photon propagates past an observer. The free electron comprises a two-dimensional planar membrane disc having a maximum charge density at the origin and transitioning to zero density at the disc radius given by de Broglie wavelength divided by 2Pi wherein the linear velocity of the free electron determines the be Broglie wavelength and radius. The photon carrying h bar of angular momentum in its E and B field lines impacts the supercurrent of free electron causing a reaction current that in turn causes the photon to be captured on the inner surface of the electron current as it forms a transient spherical bound state.  The resulting two-dimensional covering of a spherical shell by great circle current loops comprises the uniform current density pattern that gives rise to electron spin as well as a standing wave being the superposition of a Fourier series of time and spherical harmonic surface charge density waves. The current pattern of the transient electronic state is formed in the same manner as the free electron current when it binds to a nucleus to form a bound atomic electron ( wherein the transiently bound photon is the source of the central field as in the case of an atomic electronic excited state ( The spherical radius of the bound transient decreases causing the spherical current and the linear current to increase as the transient bound state electron ionizes to a free electron with an increased velocity and decreased radius and de Broglie wavelength wherein the energy of the absorbed photon is conserved in the corresponding increased rotational and translational kinetic energies.