The basic principle of light absorption
When light (which can be viewed as a series of photons) shines on a substance, the electrons in the substance can absorb the energy of the photons. If the energy of a photon matches the energy required for an electron to transition from one energy level to a higher energy level, the electron will absorb the photon and transition from a lower energy level to a higher energy level. This process reduces the intensity of light passing through the substance, as some of the light energy is converted into the internal energy of the substance.
Light absorption refers to the phenomenon where when light waves pass through a substance, some of the light energy is absorbed by the substance, resulting in a decrease in the intensity of the light waves after passing through the substance. This process involves the interaction between photons and matter, where the energy of photons is transferred to the atoms or molecules of matter, causing a change in their energy levels. Light absorption is a fundamental concept in spectroscopy, photochemistry, and many other scientific fields, which is crucial for understanding and applying the interaction between light and matter.
The phenomenon of light absorption has a wide range of applications in scientific research and technology:
Spectroscopy: By analyzing the characteristics of a substance’s absorption of specific wavelengths of light (absorption spectrum), the composition, structure, and concentration of the substance can be determined. For example, UV Vis spectroscopy is a commonly used analytical method for measuring the absorption of ultraviolet and visible light by substances.
Photochemistry: Light absorption is the starting point of photochemical reactions, in which molecules that absorb light undergo chemical changes. This principle has been applied in fields such as photodynamic therapy, photocatalysis, and solar cells.
Materials Science: By designing the light absorption properties of materials, various optoelectronic devices such as solar cells and photosensitive sensors can be developed.
Measurement of light absorption
The intensity of light absorption is usually measured through absorption spectra, which display the absorption intensity of a substance towards different wavelengths of light. A key parameter of absorption spectroscopy is the absorption peak, which is the wavelength at which a substance absorbs the maximum intensity of light. It reflects the energy level differences and electronic structure of the substance.