Optical-beam error

{
  "id": "MLC-T-CHM-008282",
  "term": "Optical-beam error",
  "field": "Chemistry",
  "definition": "An absorbance error in spectrophotometry that arises from the geometry of the radiation beam and not from the sample itself. In a wavelength-scanning instrument the image on the photodetector can shift as the wavelength changes, and radiation reflected between the cell walls adds to the transmitted signal. The reflection effect makes the measured absorbance slightly higher than the true value.",
  "subject": "Analytical Chemistry",
  "see_also": [
    "absorbance",
    "wavelength"
  ],
  "references": [
    "PAC, 1988, 60, 1449. 'Nomenclature, symbols, units and their usage in spectrochemical analysis - VII. Molecular absorption spectroscopy, ultraviolet and visible (UV/VIS) (Recommendations 1988)' on page 1457 (https://doi.org/10.1351/pac198860091449)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/optical-beam-error/"
}