When a gamma ray emitted by the nucleus of an atom hits a different atom, it may be absorbed producing a photoelectron of well-defined energy ( this used to be called " external conversion " ).
2.
He thus wants to integrate them into salvation given by Christ without them having to become Christians themselves; an external conversion does not seem necessary to him, he rather envisages an " internal conversion " of Muslims within Islam . ( Borrmans, 130)