FAQs

The term “absorption” refers to the process by which a substance takes up or assimilates another substance. This term is often used in various scientific disciplines to describe different phenomena:

In chemistry, absorption often refers to the process by which atoms, ions or molecules are taken up by another substance. For example, a sponge absorbs water by taking it into its pores.

In physics, absorption is often associated with electromagnetic waves. When electromagnetic radiation (e.g. light or radio waves) hits a material, some of the energy can be absorbed by the material, causing it to heat up. Different materials have different levels of absorption for different wavelengths of electromagnetic radiation.

In biology, absorption refers to the uptake of substances (e.g. nutrients) by cells or tissue. In the digestive system, for example, nutrients from food are absorbed by the intestinal walls into the bloodstream.

Essentially, absorption involves the uptake or assimilation of one substance by another, resulting in a change in the properties or state of the absorbing material. The context in which the term is used determines the specific nature and effects of the absorption process.

An absorption band is a range of wavelengths in the electromagnetic spectrum in which a substance absorbs light. Each type of molecule or chemical compound has a unique pattern of absorption bands that can be used for identification and analysis in various scientific fields.

Here’s how it works:

Electromagnetic spectrum: The electromagnetic spectrum includes a range of wavelengths corresponding to different forms of electromagnetic radiation, from radio waves to gamma rays. Visible light is only a small part of this spectrum.

Interaction with matter: When electromagnetic radiation, such as light, passes through or interacts with matter, certain molecules or atoms can absorb certain wavelengths of light. This absorption occurs due to transitions of electrons between energy levels or vibrational modes within the molecules.

Absorption spectrum: The absorption spectrum of a substance is a representation of the amount of light that is absorbed at each wavelength. Absorption bands appear as peaks or valleys in this spectrum and indicate the wavelengths of light that are absorbed by the substance.

Interaction with matter: When electromagnetic radiation, such as light, penetrates matter or interacts with it, certain molecules or atoms can absorb certain wavelengths of light. This absorption occurs due to transitions of electrons between energy levels or vibrational modes within the molecules.

Absorption spectrum: The absorption spectrum of a substance is a representation of the amount of light that is absorbed at each wavelength. Absorption bands appear as peaks or valleys in this spectrum and indicate the wavelengths of light that are absorbed by the substance.

Identification and analysis: The unique absorption bands of a substance serve as a fingerprint that can be used for identification. Spectroscopy techniques such as infrared (IR), ultraviolet (UV-Vis) or nuclear magnetic resonance (NMR) spectroscopy rely on the analysis of absorption bands to identify and characterise compounds.

One example:

In UV-Vis spectroscopy, molecules absorb light in the ultraviolet or visible range, which leads to the formation of absorption bands. The position and intensity of these bands provide information about the electronic structure of the molecules.

Understanding absorption bands is of fundamental importance for analytical chemistry, environmental sciences, astrophysics and various other fields where the identification and characterisation of substances is crucial.