two-dimensional correlation spectroscopy 

Synonym: 2-D correlation spectroscopy
https://doi.org/10.1351/goldbook.08295
Measurement principle of spectroscopy in which spectra are recorded at different magnitudes of an applied external perturbation of the sample and are processed to yield a 2-D correlation spectrum.
Notes:
  1. The external perturbation may be time dependent (chemical reactions, physical relaxation processes), or static (temperature change, concentration change).
  2. Correlation spectroscopy is used in infrared spectroscopy, nuclear magnetic resonance spectroscopy (COSY, TOCSY), fluorescence spectroscopy and others.
Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 677 [Terms] [Paper]