[Microbiology] Hemoglobin detection at 540 nm or 430 nm

[MICHAEL T. PALERMO, JD, CFP]

I am writing a novel that I want to be (somewhat) technically precise.  In
referring to the wavelengths above (reference to which I stumbled upon in an
online message post), I assume you are talking about absorption peaks?
 
Would you be kind enough to tell me what sort of sprectrophotometry you are
talking about?
 
Thanks very much.
 
Mike Palermo