An absorption spectrum occurs when a material absorbs certain wavelengths of light while allowing others to pass through or be transmitted. It is typically observed when white light passes through a sample or interacts with a material.
Here's a simplified explanation of how an absorption spectrum occurs:
White light: White light is a combination of various wavelengths of light, including all the colors of the visible spectrum (red, orange, yellow, green, blue, indigo, and violet). It contains photons of different energies corresponding to these wavelengths.
Interaction with a material: When white light interacts with a material, such as a gas, liquid, or solid, the photons of light can be absorbed by the electrons within the material.
Electron transitions: Within an atom or molecule, electrons can exist in different energy levels or orbitals. When a photon of light with a specific energy (corresponding to a particular wavelength) interacts with an electron, it can promote the electron to a higher energy level.
Absorption of specific wavelengths: The material's properties, such as its atomic or molecular structure, determine which wavelengths of light can be absorbed. If the energy of the incident photon matches the energy difference between two energy levels in the material, the photon will be absorbed, and the electron will transition to a higher energy level. The absorbed energy is used to promote the electron to the higher level.
Absorption spectrum: As white light passes through the material, certain wavelengths of light are absorbed, while others are transmitted or pass through the material without being significantly absorbed. The resulting transmitted light or light that reaches our eyes is missing the specific wavelengths that were absorbed. This creates dark bands or lines in the spectrum at the corresponding absorbed wavelengths, resulting in an absorption spectrum.
The absorption spectrum is unique to each material and can provide valuable information about its composition and properties. It is commonly used in various scientific fields, such as chemistry, physics, and astronomy, for identification and analysis of substances.