Surface energy transfer
Surface energy transfer (SET) is a dipole-surface energy transfer process involving a metallic surface and a molecular dipole. == Formula == The SET rate follows the inverse of the fourth power of the distance k SET = 1 τ D ( d 0 d ) 4 {\displaystyle k_{\text{SET}}={\frac {1}{\tau _{D}}}\left({\frac {d_{0}}{d}}\right)^{\! 4}} where τ D {\displaystyle \tau _{D}} is the donor emission lifetime; d {\displaystyle d} is the distance between donor-acceptor; d 0 {\displaystyle d_{0}} is the distance at which SET efficiency decreases to 50% (i.e., equal probability of energy transfer and spontaneous emission).