What observational technique utilizes narrow filters to isolate light emitted by specific atomic transitions, revealing the distribution of trace elements?

Answer

Narrowband imaging

This technique isolates the light produced when specific excited atoms, such as Oxygen-III or Sulfur-II, transition energy states, making the distribution of these trace elements visually apparent.

What observational technique utilizes narrow filters to isolate light emitted by specific atomic transitions, revealing the distribution of trace elements?
SpaceastronomycompositionnebulaElements