Resonantly enhanced multiphoton ionization spectrum of the neutral green fluorescent protein chromophore

Jason B. Greenwood*, Jordan Miles, Simone De Camillis, Peter Mulholland, Lijuan Zhang, Michael A. Parkes, Helen C. Hailes, Helen H. Fielding

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Citations (Scopus)


The photophysics of the green fluorescent protein is governed by the electronic structure of the chromophore at the heart of its β-barrel protein structure. We present the first two-color, resonance-enhanced, multiphoton ionization spectrum of the isolated neutral chromophore in vacuo with supporting electronic structure calculations. We find the absorption maximum to be 3.65 ± 0.05 eV (340 ± 5 nm), which is blue-shifted by 0.5 eV (55 nm) from the absorption maximum of the protein in its neutral form. Our results show that interactions between the chromophore and the protein have a significant influence on the electronic structure of the neutral chromophore during photoabsorption and provide a benchmark for the rational design of novel chromophores as fluorescent markers or photomanipulators.

Original languageEnglish
Pages (from-to)3588-3592
Number of pages5
JournalJournal of Physical Chemistry Letters
Issue number20
Publication statusPublished - 16 Oct 2014
Externally publishedYes


  • absorption
  • femtosecond
  • gas phase
  • time-dependent density functional theory
  • ultraviolet

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