Highlights from CISI Researchers in the Past Year

Methodology for Generating Liquid-Liquid Interfaces in a Free Flowing Liquid Sheets

CISI collaborator DJ Hoffmann and principle investigator Jake Koralek, both at SLAC National Accelerator Laboratory, have devised a method to generate multilayer liquid heterostructures in a liquid sheet. Using converging microfluidic liquid jet nozzles to shoot jets of water and oil together enables the creation of ultrathin liquid-liquid interfaces that can be as thin as hundreds of atoms thick. This breakthrough in liquid sheet technology will enable cutting-edge spectroscopic measurements of liquid-liquid interfaces, offering unprecedented insights into interfacial molecular structure and chemical reactivity.

Check out the full paper using the following link:

https://pubs.acs.org/doi/10.1021/acs.langmuir.2c01724

Machine Learning Approaches to Improve the Calculation of Optical Spectra in Hydrogen-Bonded Systems

The Isborn group at UC Merced, in collaboration with the Markland group at Stanford, has used transfer machine learning approaches to simulate the optical spectroscopy of the chromophore anion of green fluorescent protein in water. This system poses a substantial challenge for theory, and accurate simulated spectra have remained elusive due to the challenges with electronic structure theory, vibronic contributions, and complex condensed phase environment. In particular, hydrogen bonding interactions with chromophores in chemical, biological, and interfacial environments play a key role in determining their electronic absorption and relaxation processes, which are manifested in their linear and multidimensional optical spectra. In this recent paper, the Isborn and Markland groups showed that machine learning can be leveraged to predict high-level wave function theory level of accuracy energy gaps for this anion in solution.

Check out the full paper using the following link:

https://pubs.acs.org/doi/full/10.1021/acs.jpclett.3c01444

Perspective on the Spontaneous Formation of Hydrogen Peroxide at Air-Water Interfaces

In a recent perspective, the Nguyen group at UC Merced explored the thermodynamic aspects, potential experiments, and theoretical approaches to study the spontaneous formation of hydrogen peroxide at the air-water interface of water microdroplets. Recent discussion on this topic have generated significant debate, with conclusive proof still elusive. The distinctive characteristics of interfacial chemistry, influenced by factors such as density fluctuations, surface tension, and surface potential are discussed. The Nguyen group suggests that indirect evidence through the detection of hydrogen byproducts and the determination of the Gibbs free energy of the interfacial reaction may be important steps in establishing the feasibility of this phenomena. Future work on this topic has the potential to advance our understanding of interfacial chemistry and have implications in aerosol and environmental chemistry.

Check out the full paper using the following link:

https://pubs.acs.org/doi/10.1021/acs.jpcb.2c07394