Transient absorption
spectroscopy using two pulses (strong pump and weak probe)
and capable of achieving a high temporal resolution. A
pump pulse excites
the sample and triggers the process under investigation. A second delayed pulse,
the
probe, monitors an optical property. By varying the time
delay between the pump and probe pulses, it is possible to assemble measurements
as a function of time. The probe pulse is typically a UV,
visible or
infrared
pulse in which case a snap-shot spectrum is taken as a function of the delay time.
Often the probe pulse is generated from a portion of the excitation beam, but it can
also be an independently generated electromagnetic pulse.
Note:
In the case of an optical probe, this interaction is formally a non-linear optical
process that is third-order in
polarization. The excitation intensity to create
the
excited state constitutes a two-field interaction and the determination of
the change in the time-dependent optical properties involves a third field
monitoring
the induced time-dependent changes in the '
linear susceptibility'.
Diffractive probes (e.g., electrons and X-rays) can also be used, in which case one
measures a
diffraction pattern as a function of time.
Source:
PAC, 2007, 79, 293
(Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006))
on page 404
Cite as:
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.
https://doi.org/10.1351/goldbook.
