Microsolvation And Photodynamics In Formic Acid-water Clusters

Sutton, Shaun

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https://hdl.handle.net/2142/116894 Copy

Description

Title

Microsolvation And Photodynamics In Formic Acid-water Clusters

Author(s)

Sutton, Shaun

Contributor(s)

• Sayres, Scott G.
• Miller, Dane
• pilarisetty, tarakeshwar
• Rotteger, Chase H.

Issue Date

2022-06-22

Keyword(s)

Clusters/Complexes

Abstract

Formic acid is the simplest carboxylic acid and plays a pivotal role in atmospheric chemistry. It is an intermediate in the Water-Gas-Shift reaction, decomposing into either CO$_{2}$ and H$_{2}$ or into H$_{2}$O and CO under ionizing radiation. Furthermore, it is important in acid rain and seeding the nucleation of water molecules in cloud formation. Here, I will present our recent work, where femtosecond lasers are applied to study the microsolvation and photodynamics of molecular gas-phase formic acid-water clusters using time-of-flight mass spectrometry. Our cluster distribution confirms the enhanced stability of (FA)$_{5}$(H2O)$_{1}$H$^{+}$, where the formic acid cluster forms a cage-like structure surrounding the water molecule. Upon exposure to high laser intensities (400 nm, 200 fs, laser intensities of 1.9x10$^{15}$ W/cm$^{2}$), the clusters undergo an enhanced ionization which produces multiply charged ions of C, O, and CO. Coulomb explosion of these ions leads to a large kinetic energy release that is shown to increase with the size of clusters. The measured values are in agreement with a Molecular Dynamics simulation of the Coulomb explosion for the mean size of the clusters within the cluster distribution, suggesting that no movement occurs during ionization. Of particular relevance, we record a large amount of signal for the carbon monoxide trication. KER values were recorded as high as 44 eV for CO$^{3+}$ for (FA)$_{2}$, but increases to 75.3 eV when the cluster distribution is shifted toward (FA)$_{5}$ as the largest signal. Potential energy curves for CO$^{3+}$ are calculated using the multireference configuration interaction (MRCI+Q) method to confirm the existence of metastable states with a large potential barrier with respect to dissociation. This combined experimental and theoretical effort confirms the existence of metastable CO$^{3+}$.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116894

DOI

https://doi.org/10.15278/isms.2022.WD09

Copyright and License Information

Copyright 2022 held by the authors

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