What term describes the atom or molecule that absorbs energy from the laser?

The term that describes the atom or molecule that absorbs energy from the laser is "chromophore." Chromophores are specific parts of molecules that are capable of absorbing light at particular wavelengths. This absorption leads to an increase in energy, which can result in various effects such as heating or chemical reactions. In the context of laser treatments, chromophores play a crucial role because they determine how effectively a laser can target different tissues based on the absorption properties specific to those chromophores.

Understanding how chromophores work is essential in fields like aesthetic medicine, where precise targeting of skin structures (like melanin in hair or vascular structures) is needed for effective treatments. The other options, while they might sound relevant, do not accurately describe the mechanism of energy absorption by molecules in this context.