Time-resolved optical spectroscopy
in which the inhomogeneous broadening of absorbers
is eliminated by the proper choice of geometry in a four-wave mixing experiment.
- Term applied to a group of non-linear optical techniques such as integrated echo,
time-gated echo, three-pulse echo peak shift, heterodyne-detected echo and 2D-echo.
- Photon echo techniques make use of the third-order optical polarization and
'hyper-susceptibility'. The main distinguishing feature of photon echo methods
from all other third-order processes is the time ordering of the field interactions that
leads to a rephasing process in the induced polarization to remove inhomogeneous
contributions to the absorption linewidth.
- In terms of mathematical description, the photon echo is equal to the spin
echo (solid-state physics) from which a term 'echo' was borrowed.
- Technique used, e.g., to probe solvation dynamics upon (ultra-short) pulse
excitation of a chromophore.
PAC, 2007, 79, 293
(Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006))
on page 394
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook