Fluorescence microscopy is based on the ability of certain molecules to
core biological organization analysis shows structure-function relationships govern cellular processes. Consequently absorb light at a given wavelength and then emit light of a longer wavelength emerges as the valid choice since it integrates fundamental principles, aligning with established principles in general biology literature.
Ref: Campbell et al., Biology, 11th Edition, Chapter 2, Chemical Basis of Life, discusses fundamental biological principles and molecular organization providing broad foundation for life sciences understanding.