absorpce

Absorpce, or absorption, is the process by which a material, medium, or system takes in energy or matter from its surroundings. In contrast to adsorption, where substances adhere to a surface, absorption involves incorporation into the volume of the absorbing substance. Absorption can refer to energy across the electromagnetic spectrum, or to the uptake of particles, nutrients, or gases by a medium or organism.

Optical absorption occurs when photons are absorbed by atoms or molecules, raising electrons to higher energy levels. The extent of absorption is described by the absorption coefficient and can be quantified by Beer's law: A = εcl, or I = I0 e^(-αx). Absorbed light is removed from a beam, leading to color and attenuation.

Acoustic absorption describes the conversion of sound energy into heat within a material, reducing reflected sound. The absorption coefficient depends on frequency and material properties; high porosity and internal friction improve absorption.

Biological and environmental absorption: The intestinal lining absorbs nutrients and water from digested food; lungs absorb oxygen and other gases. Environmental science also studies the absorption of pollutants by soils and vegetation.

Measuring absorption: Key concepts include absorbance, transmittance, and reflectance. Spectroscopic methods determine how much light is absorbed at specific wavelengths. Beer's law relates absorbance to concentration and path length.

Applications include spectroscopy, solar energy, medical imaging, and insulation.