Biological Nuclear Transmutations as a Source of Biophotons
  Soft multi-photon radiation from hard higher energy reaction sources can be employed to describe three major well established properties of biophoton radiation; Namely, (i) the mild radiation intensity decreases for higher frequencies, (ii) the coherent state Poisson counting statistics, and (iii) the time delayed luminescence with a hyperbolic time tail. Since the soft photon frequencies span the visible to the ultraviolet frequency range, the hard reaction sources have energies extending into the nuclear transmutation regime. 
A. Widom, Y.N. Srivastava, S. Sivasubramanian
physics.gen-ph