Centre

{
  "id": "MLC-T-CHM-001793",
  "term": "Centre",
  "field": "Chemistry",
  "definition": "The velocity position of a Mössbauer spectrum that would be seen with no magnetic or quadrupole splitting, which for a split pattern is the weighted centre of the lines. Measured against a reference absorber such as alpha-iron, this position is the isomer shift, which reflects the electron density at the nucleus. A small contribution from the second-order Doppler shift, which depends on temperature, is included in it.",
  "subject": "Physical and Biophysical Chemistry",
  "see_also": [
    "resonance"
  ],
  "references": [
    "PAC, 1976, 45, 211. 'Nomenclature and Conventions for Reporting Mössbauer Spectroscopic Data' on page 215 (https://doi.org/10.1351/pac197645030211)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/centre/"
}