Difference transition

{
  "id": "MLC-T-CHM-003164",
  "term": "Difference transition",
  "field": "Chemistry",
  "definition": "A combination transition that does not start from the ground vibrational state, in which at least one vibrational quantum number rises while at least one other falls, so the band lies near the difference of the fundamental wavenumbers involved. Because it starts from a thermally populated excited vibrational level, a difference band is weak at room temperature and gains intensity as the sample is heated.",
  "synonyms": [
    "difference band",
    "difference tone"
  ],
  "subject": "Analytical Chemistry",
  "see_also": [
    "combination transition"
  ],
  "references": [
    "PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 743 (https://doi.org/10.1515/pac-2019-0203)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/difference-transition/"
}