Quadrupole and hexadecapole transition dipole moment alignment in fluorescent protein Homo-FRET

T. A. Masters, N. A. Robinson, R. J. Marsh, T. S. Blacker, D. A. Armoogum, B. Larijani, A. J. Bain

Research output: Chapter or section in a book/report/conference proceedingChapter in a published conference proceeding


Polarized time resolved fluorescence measurements are used to characterise the structure of the two-photon tensor in the enhanced green fluorescent protein (EGFP) and predict the "hidden" degree of hexadecapole transition dipole alignment (α40) created by two-photon absorption (TPA). We employ a new method for the accurate STED measurement of the evolution of (α40) by analysing the saturation dynamics of the orthogonally polarized components of two-photon excited EGFP fluorescence as a function of the time delay between the 800 nm pump and 570 nm dump pulses. The relaxation of (α40) by homo-FRET is found to be considerably greater than that for the fluorescence anisotropy which directly measures the quadrupolar transition dipole moment alignment (α20). Our results indicate that higher order dipole moment correlation measurements promise to be a sensitive probe of resonance energy transfer dynamics.

Original languageEnglish
Title of host publicationNanophotonics VII
EditorsDavid L. Andrews, Andreas Ostendorf, Angus J. Bain, Jean-Michel Nunzi
ISBN (Electronic)9781510618701
Publication statusPublished - 4 May 2018
EventNanophotonics VII 2018 - Strasbourg, France
Duration: 22 Apr 201826 Apr 2018

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceNanophotonics VII 2018

Bibliographical note

Funding Information:
We are grateful to the Engineering & Physical Sciences Research Council for financial support of this work through PhD

Publisher Copyright:
© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.


  • fluorescent protein
  • FRET
  • molecular alignment
  • rotational diffusion
  • STED
  • Stimulated Emission Depletion
  • Two-photon

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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