metastable background

in secondary-ion mass spectrometry
https://doi.org/10.1351/goldbook.09407
Intensity in a mass spectrum arising from ions that spontaneously fragment between emission and detection.
Note: In reflectron time-of-flight mass spectrometers, the decay of metastable ions leads to broad peaks at a mass dependent on the drift energy and reflector voltage. Good design minimizes these background signals.
Source:
PAC, 2020, 92, 1781. (Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)) on page 1841 [Terms] [Paper]