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Publication Detail
Stimulated emission depletion following two photon excitation.
  • Publication Type:
    Conference
  • Authors:
    Marsh RJ, Armoogum DA, Bain AJ
  • Publisher:
    SPIE-INT SOC OPTICAL ENGINEERING
  • Publication date:
    2002
  • Pagination:
    45, 54
  • Published proceedings:
    NONLINEAR SPECTROSCOPY
  • Volume:
    4812
  • Editors:
    Andrews DL
  • ISBN-10:
    0-8194-4580-0
  • Name of conference:
    Conference on Nonlinear Spectroscopy
  • Conference place:
    SEATTLE, WA
  • Conference start date:
    08/07/2002
  • Conference finish date:
    09/07/2002
  • Print ISSN:
    0277-786X
  • Language:
    EN
  • Keywords:
    two photon, stimulated emission, fluorescence lifetime, anisotropy, vibrational relaxation, fluorescein, PICOSECOND POLARIZED FLUORESCENCE, ANISOTROPIC FLUID MEDIA, SPECTROSCOPY, MICROSCOPY
Abstract
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.
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