Beam diameter

{
  "id": "MLC-T-CHM-001164",
  "term": "Beam diameter",
  "field": "Chemistry",
  "definition": "The diameter of a beam, taken in surface analysis as the diameter within which 68 percent of the electrons fall, which for a Gaussian beam corresponds to twice the standard deviation of the intensity distribution. It is found by sweeping the beam over a very sharp edge and measuring how many electrons get through. Other conventions, such as the full width at half maximum, give a larger value for a Gaussian beam.",
  "subject": "Analytical Chemistry",
  "references": [
    "PAC, 1983, 55, 2023. 'Nomenclature, symbols and units recommended for in situ microanalysis (Provisional)' on page 2027 (https://doi.org/10.1351/pac198355122023)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/beam-diameter/"
}