Absorptanssi

Absorptanssi is a Finnish term used primarily in spectroscopy to denote absorbance, the fraction of light at a given wavelength that is absorbed by a sample. It is a dimensionless quantity that reflects the optical density of the sample and is commonly reported in UV–visible spectrophotometry.

In practical terms, absorptanssi is defined as A = log10(I0/I), where I0 is the incident light intensity and I is the transmitted intensity after passing through the sample. Transmittance T is I/I0, and absorptanssi can also be expressed as A = -log10(T). When applying the Beer-Lambert law, absorptanssi equals εlc, where ε is the molar absorptivity (extinction coefficient), l is the optical path length, and c is the sample concentration. This relationship allows quantitative determination of concentrations from measured absorbance values, using calibration curves or standard solutions.

Absorptanssi is routinely measured with spectrophotometers across the ultraviolet, visible, and near-infrared ranges. In reporting, it is common to present absorbance values as dimensionless numbers, though some instrumental conventions use optical density (OD) or arbitrary units for specific methods.

Apart from science, the word absorptanssi may appear in Finnish-language texts discussing light absorption, spectroscopy, or related analytical techniques. The English equivalents are absorbance or optical density, while the Finnish terms can vary by context and discipline.

See also: Absorbance, Optical density, UV–Vis spectrophotometry, Beer-Lambert law, Spectrophotometry.