There are, not surprisingly, differing views on this phenomena within the charismatic and Pentecostal bodies. This is an even handed treatment, in my opinion...
http://www.bible-knowledge.com/Slain-in-the-Sp irit.html ...
Please note that the phrase itself is not found in the Scripture(s). Having experienced a similar presence of God (although not being 'slain") I can attest to the overwhelming peace and love that accompanies such experiences. I think of one word when trying to express what happens at such times and it has to be
Joy. A joy that is expressed in Nehemiah 8:10, "...for the joy of the LORD is your strength..�
One verse quoted in this article is (John 18:6). I think it needs an explanation and is the best example of the occurrences of the results when God directly intervenes with an individual. The falling down of those attempting to take
Yeshua captive occurred when He uttered the words "I am (He)"... "I am that I am" is what
Adonai Elohim told Moses at the burning bush when Moses asked "who shall I say sent me?" Often interpreted as YHWH. Yeshua also identified Himself with "I am" in many other references, most especially in Mark 14:61-62. His referring to Himself as "I am" is most likely the primary reason the High Priest and Pharisees determined to kill Him...
(I'll take your statement of interest at face value and I'm happy to respond, but don't expect any argument in defense.)