The second is the so-called photon-mode in which a variety of phenomena have been known, although underlying mechanisms are still largely speculative because the structural changes are vague (except those grouped under (3) in Fig. 1).
The second is theso-called photon-mode in which a variety of phenomenahave been known, although underlying mechanisms arestill largely speculative because the structural changes arevague (except those grouped under (3) in Fig. 1).