Data Files Accompanying: 
“Bulk Contributions Modulate the Sum-Frequency Generation Spectra of
Interfacial Water on Model Sea-Spray Aerosols"

Authors: 
Sandeep K. Reddy, Raphael Thiraux, Bethany A. Wellen Rudd, Lu Lin,
Tehseen Adel, Tatsuya Joutsuka, Franz M. Geiger, Heather C. Allen, Akihiro
Morita, and Francesco Paesani 

Journal: 
Chem

Contact: 
Francesco Paesani, fpaesani@ucsd.edu, Department of Chemistry and
Biochemistry, University of California San Diego; Materials Science and
Engineering, University of California San Diego; San Diego Supercomputer
Center, University of California San Diego


Cite as:
Sandeep K. Reddy, Raphael Thiraux, Bethany A. Wellen Rudd, Lu Lin, Tehseen
Adel, Tatsuya Joutsuka, Franz M. Geiger, Heather C. Allen, Akihiro Morita, and
Francesco Paesani (2018). Data from: Bulk Contributions Modulate the
Sum-Frequency Generation Spectra of Interfacial Water on Model Sea-Spray
Aerosols.  In Center for Aerosol Impacts on Chemistry of the Environment
(CAICE). UC San Diego Library Digital Collections. https://doi.org/10.6075/J08C9TFW


Description:
Publication abstract: Vibrational sum-frequency generation (vSFG) spectroscopy
is used to determine the molecular structure of water at the interface of
palmitic acid monolayers. Both measured and calculated spectra display specific
features due to third-order contributions to the vSFG response which are
associated with finite interfacial electric potentials. We demonstrate that
theoretical modeling enables to separate the third-order contributions, thus
allowing for a systematic analysis of the strictly surface-sensitive,
second-order component of the vSFG response. This study provides fundamental,
molecular-level insights into the interfacial structure of water in a neutral
surfactant system with relevance to single layer bio-membranes and
environmentally relevant sea-spray aerosols. Our results emphasize the key role
that computer simulations can play in interpreting vSFG spectra and revealing
microscopic details of water at complex interfaces, which can be difficult to
extract from experiments due to the mixing of second-order, surface-sensitive
and third-order, bulk-dependent contributions to the vSFG response.


Scope and content:
This package contains an explanatory readme file in each sub-folder,
input files needed to run the simulations and the FORTRAN and C++ programs
to calculate the sum-frequency generation spectrum,
and the decomposition of vSFG spectrum 
in terms of hydrogen bonding. Since the total size
of the trajectories is > 3TB, we only provide
the input files. The details of computational
methods and experimental measurements are also provided. 

Softwares:

1. LAMMPS: An open-source molecular dynamics package

http://lammps.sandia.gov/

2. DLPOLY_2.0: A open-source molecular dynamics package which is modified to
include MB-pol water model. It can be downloaded for free using the below link, 

http://paesanigroup.ucsd.edu/software/mbpol_ipi.html

3. SFG spectrum: It is calculated with in-house software which is provided
along with the data (filename: dipole_polarizability.zip). Instructions on how to compile
the code are also provided in the zipped file.  

Topics:
Computational Chemistry
Sea-salt Aerosols
Sum-frequency Genegration spectroscopy
Molecular dynamics

Related Publications:
1. Ellen M. Adams, Bethany A. Wellen, Raphael Thiraux, Sandeep K. Reddy, Andrew
S. Vidalis, Francesco Paesani and Heather C. Allen (20107) Sodium–carboxylate
contact ion pair formation induces stabilization of palmitic acid monolayers at
high pH.