scholarly journals Time-Resolved Vibrational Analysis of Excited State Ab Initio Molecular Dynamics to Understand Photorelaxation: The Case of the Pyranine Photoacid in Aqueous Solution

2020 ◽  
Vol 16 (10) ◽  
pp. 6007-6013 ◽  
Author(s):  
Maria Gabriella Chiariello ◽  
Greta Donati ◽  
Nadia Rega
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Excited State ◽  
Ab Initio ◽  
Vibrational Analysis ◽  
Ab Initio Molecular Dynamics ◽  
Time Resolved

Unveiling anharmonic coupling by means of excited state ab initio dynamics: application to diarylethene photoreactivity

2019 ◽  
Vol 21 (7) ◽  
pp. 3606-3614 ◽  
Author(s):  
Maria Gabriella Chiariello ◽  
Umberto Raucci ◽  
Federico Coppola ◽  
Nadia Rega
Keyword(s):  
Excited State ◽  
Ab Initio ◽  
Vibrational Analysis ◽  
Time Resolved ◽  
Anharmonic Coupling ◽  
New Time

We adopted excited state ab initio dynamics and a new time resolved vibrational analysis to unveil coupling between modes promoting photorelaxation.

Ab Initio Molecular Dynamics Simulations of an Excited State of X-(H2O)3(X = Cl, I) Complex

2005 ◽  
Vol 109 (42) ◽  
pp. 9419-9423 ◽  
Author(s):  
M. Kołaski ◽  
Han Myoung Lee ◽  
Chaeho Pak ◽  
M. Dupuis ◽  
Kwang S. Kim
Keyword(s):  
Molecular Dynamics ◽  
Excited State ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Ab Initio Molecular Dynamics ◽  
Dynamics Simulations

Erbium(III) in Aqueous Solution: An Ab Initio Molecular Dynamics Study

2013 ◽  
Vol 117 (48) ◽  
pp. 15151-15156 ◽  
Author(s):  
Lorenz R. Canaval ◽  
Theerathad Sakwarathorn ◽  
Bernd M. Rode ◽  
Christoph B. Messner ◽  
Oliver M. D. Lutz ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Ab Initio ◽  
Ab Initio Molecular Dynamics

Excess electron interaction with radiosensitive 5-bromopyrimidine in aqueous solution: a combined ab initio molecular dynamics and time-dependent wave-packet study

2015 ◽  
Vol 17 (30) ◽  
pp. 19797-19805 ◽  
Author(s):  
Changzhe Zhang ◽  
Yuxiang Bu
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Wave Packet ◽  
Ab Initio ◽  
Excess Electron ◽  
Time Dependent ◽  
Ab Initio Molecular Dynamics ◽  
Electron Interaction ◽  
Secondary Electrons ◽  
Target Molecule

Radiation-generated secondary electrons can induce resonance processes in a target molecule and fragment it via different pathways.

scholarly journals Proton Transfer from a Photoacid to Water: First Principles Simulations and Fast Fluorescence Spectroscopy

2021 ◽  
Author(s):  
Alice R. Walker ◽  
Boning Wu ◽  
Jan Meisner ◽  
Michael D. Fayer ◽  
Todd J. Martinez
Keyword(s):  
Molecular Dynamics ◽  
Excited State ◽  
Fluorescence Spectroscopy ◽  
Proton Transfer ◽  
Ab Initio ◽  
Time Constant ◽  
Emission Wavelength ◽  
Ab Initio Molecular Dynamics ◽  
Long Distance ◽  
Hydrogen Bonded

Proton transfer reactions are ubiquitous in chemistry, especially in aqueous solutions. We investigate photo-induced proton transfer between the photoacid 8-hydroxypyrene-1,3,6- trisulfonate (HPTS) and water using fast fluorescence spectroscopy and ab initio molecular dynamics simulations. Photo-excitation causes rapid proton release from the HPTS hydroxyl. Previous experiments on HPTS/water described the progress from photoexcitation to proton diffusion using kinetic equations with two time constants. The shortest time constant has been interpreted as protonated and photoexcited HPTS evolving into an “associated” state, where the proton is “shared” between the HPTS hydroxyl and an originally hydrogen bonded water. The longer time constant has been interpreted as indicating evolution to a “solvent separated” state where the shared proton undergoes long distance diffusion. In this work, we refine the previous experimental results using very pure HPTS. We then use excited state ab initio molecular dynamics to elucidate the detailed molecular mechanism of aqueous excited state proton transfer in HPTS. We find that the initial excitation results in rapid rearrangement of water, forming a strong hydrogen bonded network (a “water wire”) around HPTS. HPTS then deprotonates in ≤3 ps, resulting in a proton that migrates back and forth along the wire before localizing on a single water molecule. We find a near linear relationship between emission wavelength and proton-HPTS distance over the simulated time scale, suggesting that emission wavelength can be used as a ruler for proton distance. Our simulations reveal that the “associated” state corresponds to a water wire with a mobile proton and that the diffusion of the proton away from this water wire (to a generalized “solvent-separated” state) corresponds to the longest experimental time constant.

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