{HEAD ~ The electron hole pairs} trapped within the active layer sensitize the activator ions, causing the activator ions to emit {TAIL ~ light} 
{ HEAD ~ The electron hole pairs } trapped within the active layer sensitize the activator ions , causing the activator ions to emit { TAIL ~ light }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL