By uncovering the mechanism of UV resonant electron emission, we show that the GFP biomimetics are more stable to photooxidation.

Femtosecond photoelectron spectroscopy measurements of dissociation CH3I show complex dynamics in the high energy region of absorption band A.

Green fluorescent protein (GFP) plays an important role in the biological and biochemical sciences as an efficient fluorescent probe and as a light-induced electron donor.

Water is the predominant medium for chemistry and biology, yet its role in determining how molecules respond to ultraviolet light is not well understood at the molecular level. Here, we combine gas-phase and liquid-microjet photoelectron spectroscopy to investigate how an aqueous environment influences the electronic structure and relaxation dynamics of phenol, a ubiquitous motif in many biologically relevant chromophores. The vertical ionization energies of electronically excited states are important quantities that govern the rates of charge-transfer reactions, and, in phenol, the vertical ionization energy of the first electronically excited state is found to be lowered by around 0.8 eV in aqueous solution. The initial relaxation dynamics following photoexcitation with ultraviolet light appear to be remarkably similar in the gas-phase and aqueous solution; however, in aqueous solution, we find evidence to suggest that solvated electrons are formed on an ultrafast time scale following photoexcitation just above the conical intersection between the first two excited electronic states.

Vibrationally state selected predissociation lifetimes for the methyl radical in the 3pz Rydberg state have been measured by femtosecond velocity map imaging and the results explained by ab initio theoretical calculations.

The photodissociation dynamics of strong-field ionized methyl iodide (\ce{CH3I}) were probed using intense extreme ultraviolet (XUV) radiation produced by the SPring-8 Angstrom Compact free electron LAser (SACLA). Strong-field ionization and...

The electronic structure and excited-state dynamics of the ubiquitous bioluminescent probe luciferin and its furthest red-shifted analogue infraluciferin have been investigated using photoelectron spectroscopy and quantum chemistry calculations. In our electrospray ionization source, the deprotonated anions are formed predominantly in their phenolate forms and are directly relevant to studies of luciferin and infraluciferin as models for their unstable oxyluciferin and oxyinfraluciferin emitters. Following photoexcitation in the range 357-230 nm, we find that internal conversion from high-lying excited states to the S(1ππ*) state competes efficiently with electron detachment. In infraluciferin, we find that decarboxylation also competes with direct electron detachment and internal conversion. This detailed spectroscopic and computational study defines the electronic structure and electronic relaxation processes of luciferin and infraluciferin and will inform the design of new bioluminescent systems and applications.

Phenolates and their substituted analogues are important molecular motifs in many biological molecules, including the family of fluorescent proteins based on green fluorescent protein. We have used a combination of anion photoelectron velocity-map imaging measurements and quantum chemistry calculations to probe the electronic structure of the phenolate anion and difluoro-and dimethoxy-substituted analogues. We report vertical detachment energies (VDEs) and quantify the photoelectron angular distributions. The VDEs for phenolate (2.26 ± 0.03 eV, 3.22 ± 0.02 eV) are in agreement with high-resolution measurements, whereas the values for the substituted analogues (2.61 ± 0.03 eV for difluorophenolate; ∼ 2.35 eV for dimethoxyphenolate) are new measurements. We also report adiabatic excitation energies (AEEs) of anion resonances and discuss their contributions to the overall photoelectron angular distributions. The AEE of the lowest lying resonance in phenolate (∼ 3.36 eV) is consistent with previous measurements, whereas the value for the next resonance (∼ 3.7 eV) is a new measurement. The AEEs of the resonances in the substituted analogues (∼ 3.74 eV for difluorophenolate; ∼ 3.4 eV and 3.74 eV for dimethoxyphenolate) are new measurements.