IUPAC - stopping cross section (09387)

stopping cross section

symbol:

S (E)

, units:

J m^{2}

J m^{2} {kg}^{- 1}

eV m^{2}

eV m^{2} {kg}^{- 1}

https://doi.org/10.1351/goldbook.09387

Rate of energy loss of a particle with distance along its trajectory in a sample divided by the atomic density of sample atoms for a sample of infinitesimal thickness.

Notes:

The atomic density is usually taken as the number density, $N$ , but sometimes as the mass density, $ρ$ . The stopping cross section is thus given either by $S (E) \equiv (1 / N) d E / d x$ or by $S (E) \equiv (1 / ρ) d E / d x$ , where $d E / d x$ is the rate of loss of energy $E$ with distance $x$ along the particle trajectory. Note that $d E / d x$ is often called the stopping power, although it is not in units of power. This inconsistency for the term stopping power leads to its deprecation.
SI unit: $J m^{2}$ or $J m^{2} {kg}^{- 1}$ . Common unit $eV m^{2}$ or $eV m^{2} {kg}^{- 1}$ .

Source:
PAC, 2020, 92, 1781. (Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)) on page 1836 [Terms] [Paper]

Citation: 'stopping cross section' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.09387 RIS BibTex EndNote

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stopping cross section