In {TAIL ~ certain embodiments}, {HEAD ~ multiple portions} of surface 501 are sequentially exposed to electromagnetic radiation 
In
In { TAIL ~ certain embodiments } , { HEAD ~ multiple portions } of surface 501 are sequentially exposed to electromagnetic radiation
REL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH