What happens in a molecular level that allows an analyze to absorb light at a certain wavelength.

Question

1: What happens in a molecular level that allows an analyze to absorb light at a certain wavelength.

2: Why are you using a specific wavelength of light to record absorbance measurements for the dye (i.e., why non't every wavelength of light be absorbed by the analyte)

Answer 1

Light is absorbed by atomic orbital transitions of electrons from a lower to higher position. As particular wavelengths of light are absorbed based on the chemical structure, the bonding, and the electrons that circulate around the atoms and the molecule. If a chemical has conjugated double bonds, it will be more absorbant of visible light, that is particularly true for organic dyes, or colored natural materials like chlorophyll or carotene, both molecules have conjugated double bonds.