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Stimulated emission depletion following two photon excitation

Marsh, RJ; Armoogum, DA; Bain, AJ; (2002) Stimulated emission depletion following two photon excitation. In: Andrews, DL, (ed.) Nonlinear Spectroscopy. Society of Photo-Optical Instrumentation Engineers (SPIE): Seattle, WA, USA. Green open access

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The technique of stimulated emission depletion of fluorescence (STED) from a two photon excited molecular population is demonstrated in the S, excited state of fluorescein in ethylene glycol and methanol. Two photon excitation (pump) is achieved using the partial output of a regeneratively amplified Ti:Sapphire laser in conjunction with an optical parametric amplifier whose tuneable output provides a synchronous depletion (dump) pulse. Time resolved fluorescence intensity and anisotropy measurements of the fluorescein emission are made using picosecond time-correlated single photon counting. Pump-dump time delayed fluorescence intensity measurements are used to characterise the response of the system and to provide additional data on saturation dynamics of the dump transition. Two photon STED is modelled using both approximate analytical techniques in the weak dump limit and by numerical solutions to the appropriate rate equations. The latter are used to fit experimental data from which it is possible to determine the cross-section for the stimulated transition and lifetime of the upper vibrational levels of the ground state.

Type: Proceedings paper
Title: Stimulated emission depletion following two photon excitation
Event: Nonlinear Spectroscopy
Location: SEATTLE, WA
Dates: 08 July 2002 - 09 July 2002
ISBN: 0819445800
Open access status: An open access version is available from UCL Discovery
DOI: 10.1117/12.451385
Publisher version: http://dx.doi.org/10.1117/12.451385
Language: English
Additional information: Copyright © 2002 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
Keywords: two photon, stimulated emission, fluorescence lifetime, anisotropy, vibrational relaxation, fluorescein, picosecond polarized fluorescence, anisotropic fluid media, spectroscopy, microscopy
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/27788
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