What is the difference [一瞬]{いっ・しゅん}, [一刻]{いっ・こく}, and [(一)刹那]{(いっ・)せつ・な}

Question

They all mean something like an instant or a moment.

• When are they (and when are they not) interchangeable?
• Is any more (in)formal/literary than the others?
• Do they represent the same amount of time?
  • My gut says that 一瞬 is the quickest (like [電光石火]{でん・こう・せっ・か}) and that 一刻 can be a longer "moment" (like 即席ラーメン or, "Can you answer a quick servey? It'll only take a moment of your time.").
  • I've never heard (一)刹那 used in real life, so I have no basis for comparison.

Answer 1

• 刹那 is clearly more literary than the others. It's originally a Buddhism term.
• As a no-adjective, 一瞬の and 刹那の are mostly interchangeable (except that the latter being literary and thus emphatic/dramatic)
• As a conjunction-like noun (?), ～した刹那 is interchangeable with ～した瞬間.
• As a na-adjective, 刹那的 means "ephemeral" (negative); 瞬間的 is "instant"; 一瞬的 makes no sense.
• 刻 is originally a unit of time that roughly corresponds to 30 minutes. Today, 一刻 is used almost exclusively in idioms (一刻を争う, 一刻一刻(と), 一刻の猶予もない, etc), and I don't know how to use 一刻 with ラーメン. 一刻 basically refers to a longer time than 一瞬/刹那. In other words, 一瞬/刹那 roughly means "less than a second" or "less than a minute" at most, whereas 一刻 roughly means "less than an hour".