Award Abstract # 1708581
Collaborative Research: A Mechanistic Study of Chemical Enhancement in Surface Enhanced Raman Spectroscopy and Graphene Enhanced Raman Spectroscopy

NSF Org: CHE
Division Of Chemistry
Recipient: UNIVERSITY OF SOUTHERN CALIFORNIA
Initial Amendment Date: July 11, 2017
Latest Amendment Date: July 19, 2017
Award Number: 1708581
Award Instrument: Continuing Grant
Program Manager: Christopher Elles
CHE
 Division Of Chemistry
MPS
 Directorate for Mathematical and Physical Sciences
Start Date: July 15, 2017
End Date: August 31, 2021 (Estimated)
Total Intended Award Amount: $265,192.00
Total Awarded Amount to Date: $265,192.00
Funds Obligated to Date: FY 2017 = $265,192.00
History of Investigator:
  • Stephen Cronin (Principal Investigator)
    scronin@usc.edu
Recipient Sponsored Research Office: University of Southern California
3720 S FLOWER ST FL 3
LOS ANGELES
CA  US  90033
(213)740-7762
Sponsor Congressional District: 34
Primary Place of Performance: University of Southern California
3720 S Flower St
Los Angeles
CA  US  90089-0001
Primary Place of Performance
Congressional District:
37
Unique Entity Identifier (UEI): G88KLJR3KYT5
Parent UEI:
NSF Program(s): Chemical Measurement & Imaging
Primary Program Source: 01001718DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s): 057Z, 7237, 8990, 9263
Program Element Code(s): 688000
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.049

ABSTRACT

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Cronin at University of Southern California and Professor Jensen at Pennsylvania State University investigate the use of Raman spectroscopy as a powerful tool that measures the energies of specific bond stretches. This technique provide the unique fingerprint for chemical identification. As such, Raman spectroscopy is extremely useful for a number of applications in chemical, environmental and threat detection monitoring. While a highly useful technique, the Raman scattering cross-section of most molecules is extremely small, and this generally limits its potential uses. Surface Enhanced Raman Scattering (SERS) and Graphene Enhanced Raman Scattering (GERS), the techniques investigated in this research project, can be used to improve the small signal intensities, thus making Raman spectroscopy-related applications more practical. In terms of broader impacts Dr. Cronin creates workshops for Los Angeles high school chemistry teachers. He leverages existing relationships between USC and its neighboring high schools (e.g., USC's Good Neighbors Campaign, Joint Education Project, and the Service Learning Program) to increase the attendance from disadvantaged schools (i.e., central Los Angeles inner city schools) serving underrepresented minority groups. The content of the workshop is reformulated to expose underrepresented students to the results and, more importantly, the excitement of research. Research projects for undergraduate students introduce them to fundamental scientific research and give them confidence to pursue careers in science and engineering. A new module devoted to SERS is developed for a new course at USC on nanoscience and nanotechnology, and their research accomplishments are discussed in class and integrated into the curriculum. Professor Jansen uses a website, nanoHub.org, to share their computational tools with scientists outside of his labs.

In this collaboration, Professors Cronin and Jensen investigate the mechanism behind the strong spectroscopic responses observed in two surface-based spectroscopic techniques: Surface Enhanced Raman Scattering (SERS) and Graphene Enhanced Raman Scattering (GERS). They use both experimental and computational tools to carefully isolate the enhanced Raman signals caused by Chemical Enhancement (CE) from those signals caused by ElectroMagnetic Enhancement (EM) in order to understand the CE mechanism. Specifically, Professor Cronin's group at USC performs Raman spectroscopy of single molecules on various SERS substrates, which enables a direct comparison with the theoretical calculations preformed at the Jensen's group at PSU. The Raman spectra are collected under various electrochemical conditions in order to explore the role of the molecule-metal energy level alignment and decouple the vibrational-mode-specific chemical enhancement from the uniform chemical enhancement. Professor Jensen's first principles calculations provide a detailed theoretical framework for interpreting chemical enhancement in SERS and GERS spectra to facilitate a better understanding of the chemical enhancement mechanism. Students in both groups experience the interdisciplinary training opportunities. Both groups' are actively engaged in outreach activities to local high school teachers and general public.

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.

Chen, Jihan and Bailey, Connor S. and Cui, Dingzhou and Wang, Yu and Wang, Bo and Shi, Haotian and Cai, Zhi and Pop, Eric and Zhou, Chongwu and Cronin, Stephen B. "Stacking Independence and Resonant Interlayer Excitation of Monolayer WSe 2 /MoSe 2 Heterostructures for Photocatalytic Energy Conversion" ACS Applied Nano Materials , v.3 , 2020 10.1021/acsanm.9b01898 Citation Details
Chen, Jihan and Bailey, Connor S. and Hong, Yilun and Wang, Li and Cai, Zhi and Shen, Lang and Hou, Bingya and Wang, Yu and Shi, Haotian and Sambur, Justin and Ren, Wencai and Pop, Eric and Cronin, Stephen B. "Plasmon-Resonant Enhancement of Photocatalysis on Monolayer WSe 2" ACS Photonics , v.6 , 2019 10.1021/acsphotonics.9b00089 Citation Details
Li, Shujin and Zhao, Bofan and Aguirre, Alejo and Wang, Yu and Li, Ruoxi and Yang, Sisi and Aravind, Indu and Cai, Zhi and Chen, Ran and Jensen, Lasse and Cronin, Stephen B. "Monitoring Reaction Intermediates in Plasma-Driven SO 2 , NO, and NO 2 Remediation Chemistry Using In Situ SERS Spectroscopy" Analytical Chemistry , v.93 , 2021 https://doi.org/10.1021/acs.analchem.0c05413 Citation Details
Shi, Haotian and Cai, Zhi and Patrow, Joel and Zhao, Bofan and Wang, Yi and Wang, Yu and Benderskii, Alexander and Dawlaty, Jahan and Cronin, Stephen B. "Monitoring Local Electric Fields at Electrode Surfaces Using Surface Enhanced Raman Scattering-Based Stark-Shift Spectroscopy during Hydrogen Evolution Reactions" ACS Applied Materials & Interfaces , v.10 , 2018 10.1021/acsami.8b11961 Citation Details
Shi, Haotian and Pekarek, Ryan T. and Chen, Ran and Zhang, Boxin and Wang, Yu and Aravind, Indu and Cai, Zhi and Jensen, Lasse and Neale, Nathan R. and Cronin, Stephen B. "Monitoring Local Electric Fields using Stark Shifts on Napthyl Nitrile-Functionalized Silicon Photoelectrodes" The Journal of Physical Chemistry C , v.124 , 2020 10.1021/acs.jpcc.0c03966 Citation Details
Song, Boxiang and Jiang, Zhihao and Liu, Zerui and Wang, Yunxiang and Liu, Fanxin and Cronin, Stephen B. and Yang, Hao and Meng, Deming and Chen, Buyun and Hu, Pan and Schwartzberg, Adam M. and Cabrini, Stefano and Haas, Stephan and Wu, Wei "Probing the Mechanisms of Strong Fluorescence Enhancement in Plasmonic Nanogaps with Sub-nanometer Precision" ACS Nano , v.14 , 2020 https://doi.org/10.1021/acsnano.0c01973 Citation Details
Zhao, Bofan and Aravind, Indu and Yang, Sisi and Cai, Zhi and Wang, Yu and Li, Ruoxi and Subramanian, Sriram and Ford, Patrick and Singleton, Daniel R. and Gundersen, Martin A. and Cronin, Stephen B. "Nanoparticle-Enhanced Plasma Discharge Using Nanosecond High-Voltage Pulses" The Journal of Physical Chemistry C , v.124 , 2020 10.1021/acs.jpcc.9b12054 Citation Details
Zhao, Bofan and Aravind, Indu and Yang, Sisi and Wang, Yu and Li, Ruoxi and Zhang, Boxin and Wang, Yi and Dawlaty, Jahan M. and Cronin, Stephen B. "Enhanced Plasma Generation from Metal Nanostructures via Photoexcited Hot Electrons" The Journal of Physical Chemistry C , v.125 , 2021 https://doi.org/10.1021/acs.jpcc.1c00765 Citation Details

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.

This project was designed to gain a deeper understanding into the physical mechanisms underlying Surface Enhanced Raman Scattering (SERS) and Graphene Enhanced Raman Scattering (GERS) phenomena. Prior to this study, the quantitative theoretical treatment of the SERS enhancement mechanism has focused largely on classical electrodynamics, with limited insight into the chemical interactions between molecular adsorbates and metallic substrates. In addition to the enhancement provided by classical electromagnetics, there is an additional chemical component that can lead to both an overall uniform enhancement and, on top of that, a vibrational-mode-specific enhancement, which makes SERS and GERS spectra appear quite different from bulk solution Raman spectra.  

 

The experimental portion of this work was carried out at USC and was directly compared with the theoretical calculations preformed at PSU. In addition to static SERS spectra, electrochemical tuning of SERS and GERS surfaces were obtained to vary the molecule-metal energy level alignment and local electric fields experienced by the surface-bound molecules. Prof. Jensen?s first principles calculations have provided a detailed theoretical framework for understanding the SERS and GERS spectra under working electrochemical conditions. In doing so, we were able to close the gap between theory and experiment.

 

Raman spectroscopy is a powerful tool that gives the precise vibrational energies of molecules, which provide the unique fingerprint for chemical identification. As such, Raman spectroscopy is extremely useful for a vast number of applications. However, the Raman scattering cross-section of most molecules is extremely small, which generally limits its potential uses. SERS can be used to improve the small Raman intensities, thus making Raman spectroscopy related applications more practical. SERS enhancements with single molecule detection sensitivity have been reported, but this magnitude of enhancement cannot be produced reliably. Typically, electromagnetic enhancement factors of 106-108 can be reproducibly achieved. However, there are currently no systematic ways of controlling the chemical enhancement part of SERS, and theory suggests only an approximate picture for why some modes can be enhanced by one to two orders of magnitude and others remain unchanged. The development of robust, reliable SERS substrates exhibiting 1010 enhancement would enable single molecule detection and identification at low laser powers (< 1 mW) with handheld spectrometers that can be used for a wide range of applications in chemical, environmental, and threat detection monitoring.

 


Last Modified: 12/30/2021
Modified by: Stephen Cronin

Please report errors in award information by writing to: awardsearch@nsf.gov.

Print this page

Back to Top of page