| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
|
| Initial Amendment Date: | March 11, 2016 |
| Latest Amendment Date: | February 23, 2018 |
| Award Number: | 1541944 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Chungu Lu
AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | March 15, 2016 |
| End Date: | February 29, 2020 (Estimated) |
| Total Intended Award Amount: | $287,769.00 |
| Total Awarded Amount to Date: | $287,769.00 |
| Funds Obligated to Date: |
FY 2017 = $84,896.00 FY 2018 = $80,567.00 |
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
201 SIKES HALL CLEMSON SC US 29634-0001 (864)656-2424 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
SC US 29634-0001 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): |
Physical & Dynamic Meteorology, CSD-Chem Strcture and Dynamics |
| Primary Program Source: |
01001718DB NSF RESEARCH & RELATED ACTIVIT 01001819DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Understanding the molecular behavior of frozen water is essential for predicting the future of our planet. Frozen water is present in the atmosphere -- in clouds -- where foreign particles such as mineral dust promote ice nucleation. Consequently, surface-assisted ice nucleation, i.e. heterogeneous ice nucleation, has a significant effect on cloud microphysics. This implies that it is important to accurately describe heterogeneous ice nucleation in order to be able to accurately model the weather and climate. Though theoretical and empirical descriptions have been developed, there is still no complete description of the requirements of the heterogeneous ice nucleation process, and no framework to know a priori if a given surface will be a good ice nucleating agent.
Through the synergistic experimental and simulation efforts, the foundation for molecular level understanding of heterogeneous ice nucleation will be built. The focus of this research will be to relate the effects of surface charge and lattice match to heterogeneous nucleation of ice with an emphasis on the free energy of formation and the nucleation rate. Straightforward molecular dynamics (MD) simulations will provide detailed insights into water behavior near mica surfaces and will be compared with experimental findings. In addition, the kinetics and thermodynamics of ice nucleation will be calculated from simulations. The research will provide the basis for building predictive models of heterogeneous ice nucleation that can be incorporated into larger scale models relevant to atmospheric chemistry and weather prediction.
The simulation tools developed and results of this research will provide the basis to answer several of the top 10 questions related to molecular behavior of frozen water as listed by Bartels-Rausch (Nature, 2013), which are essential for predicting the future of our planet. Phase transitions assisted by surfaces in aqueous systems are relevant to a wide variety of fields and processes including biological assemblies, surfactants, nanotoxicology, semiconductor industry, food industry and others. Also, the research presents several learning opportunities for graduate and undergraduate students in different forms. The collaborative nature of this research and the exchange program between the two scientist groups will expose the students to a multitude of tools used to study challenging problems in atmospheric chemistry.
The simulations will be used to develop informative videos to be used as educational tools as well as for recruitment of students into science and engineering. User-friendly modules that enable students to perform some simple molecular simulations, which can be used as supplements for class lectures to illustrate concepts in thermodynamics, kinetics and materials will be developed. These will be available to the scientific community free-of-charge. The results from the research will be published in peer-reviewed journals and will be presented in various national and international meetings.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Ice nucleation, that is the initiation of the transformation of liquid water to ice, is an important phenomenon in the clouds. Most ice nucleation is influenced by the presence of foreign particles like mineral dust. The effects of these foreign particles are not well-understood and limit our understanding of cloud physics. Nucleation occurs at the time and lengthscales that are very challenging to probe in experiments. On the other hand, while computer simulations are designed to probe the relevant spatial and temporal regimes, important surface features such as surface defects are not easily captured. This makes it difficult to directly relate experimental and simulation studies.
In our research, we have focused on mica surface that is atomistically smooth (and hence, defect free) in experiments. In addition, the surface cation can be exchanged providing a surface feature that can be changed without affecting other surface parameters. These enable us to study similar systems in both experiments and simulations and thus, use the synergy to probe the effect of surface charges on ice nucleation. To the best of our knowledge, this is the first-time surface charge effects on ice nucleation on mica have been studied. We performed molecular dynamics simulations of water on mica with various surface cations. The cations studied included K+ and Ca2+, and hypothetical ions K2+, K3+, Ca+, Ca3+. Our collaborators performed freezing experiments on mica surfaces with various cations. The cations studied were K+, Ca2+, Mg2+, Sr2+, and Al3+. Through a combined experimental and simulation approach we discovered that multivalent cations can increase ice nucleation efficiency of mica surfaces. We proposed a novel mechanism of ice nucleation catalyzed by surface charges ? the multivalent ions facilitated formation of large clusters of hydrogen bonded water molecules with large fraction of water free to adapt ice-like orientations. This enhances the probability of the formation of ice nuclei leading to the enhanced ice nucleation on mica with multivalent cations. This sheds new light on the complex interplay of surface properties in governing heterogeneous ice nucleation.
Last Modified: 07/30/2020
Modified by: Sapna Sarupria
Please report errors in award information by writing to: awardsearch@nsf.gov.
