Emission photo-spectroscopy and Absorption photo-spectroscopy.

Atomic absorption spectrophotometry is a method in analytical chemistry.

This is the absorption of photons with specific wavelengths by different types of materials.

Fluorescence spectroscopy is a type of spectroscopy that analyzes fluorescence from a provided sample. This uses a beam of light, often an ultraviolet light which then causes absorption spectroscopy to occur.

Absorption spectroscopy refers to spectroscopic techniques that measure the absorption of radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i.e., photons, from the radiating field. The intensity of the absorption varies as a function of frequency, and this variation is the absorption spectrum. Absorption spectroscopy is performed across the electromagnetic spectrum.