J-modulated spin-echo

{
  "id": "MLC-T-CHM-006285",
  "term": "J-modulated spin-echo",
  "field": "Chemistry",
  "definition": "A pulse sequence in carbon-13 NMR in which a spin echo is allowed to evolve under the one-bond C-H coupling, so that the phase of each carbon signal is modulated by the number of attached protons. With a delay of 1/J, quaternary carbons and CH2 groups appear with one sign and CH and CH3 groups with the opposite sign. It is also known as the attached proton test (APT).",
  "subject": "Analytical Chemistry",
  "see_also": [
    "pulse sequence",
    "spin echo"
  ],
  "references": [
    "PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 694 (https://doi.org/10.1515/pac-2019-0203)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/j-modulated-spin-echo/"
}