Comparable Enhancement of TERS Signals from WSe2 on Chromium and Gold

Krayev, Andrey V.; Krylyuk, Sergiy; Ilic, Robert; Hight Walker, Angela; Bhattarai, Ashish; Joly, Alan G.; Velicky, Matej; Davydov, Albert; El-Khoury, Patrick Z.

doi:10.1021/acs.jpcc.0c01298

Title: Comparable Enhancement of TERS Signals from WSe₂ on Chromium and Gold

Abstract

Plasmonic tip-sample junctions, at which the incident and scattered optical fields are localized and optimally enhanced, are often exploited to achieve ultrasensitive and highly spatially localized tip-enhanced Raman scattering (TERS). Recent work has demonstrated that the sensitivity and spatial resolution that are required to probe single molecules are attainable in such platforms. In this work, we observe and rationalize comparable TERS from few-layer WSe₂ single crystals exfoliated onto Au- and Cr-coated Si substrates, using a plasmonic TERS probe excited with a 638-nm laser. Our experimental observations are supported by finite-difference time-domain simulations that illustrate that the attainable field enhancement factors at the Au-Au and Au-Cr tip-sample nanojunctions are comparable in magnitude. Furthermore, through a combined experimental and theoretical analysis, we propose that besides Au/Ag, several metallic substrates may be used to record bright TERS spectral images.

Authors:

Krayev, Andrey V. ^[1]; Krylyuk, Sergiy ^[2]; Ilic, Robert ^[3]; Hight Walker, Angela ^[3]; Bhattarai, Ashish ^[4]; Joly, Alan G. ^[4]; Velicky, Matej ^[5]; Davydov, Albert ^[6];

^[4]

Horiba Instruments Inc., Novato, CA (United States)
National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Material Measurement Lab.; Theiss Research, Inc., La Jolla, CA (United States)
National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Physical Measurement Lab.
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Cornell Univ., Ithaca, NY (United States); Univ. of Manchester (United Kingdom)
National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Material Measurement Lab.

Publication Date:: 2020-04-06

Research Org.:: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Office of Biological and Environmental Research (BER); National Institute of Standards and Technology (NIST)

OSTI Identifier:: 1708858

Report Number(s):: PNNL-SA-140248
Journal ID: ISSN 1932-7447

Grant/Contract Number:: AC05-76RL01830; 70NANB18H155

Resource Type:: Accepted Manuscript

Journal Name:: Journal of Physical Chemistry. C

Additional Journal Information:: Journal Volume: 124; Journal Issue: 16; Journal ID: ISSN 1932-7447

Publisher:: American Chemical Society

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Crystals; metals; gold; plasmonics; Raman spectroscopy

Citation Formats


                    Krayev, Andrey V., Krylyuk, Sergiy, Ilic, Robert, Hight Walker, Angela, Bhattarai, Ashish, Joly, Alan G., Velicky, Matej, Davydov, Albert, and El-Khoury, Patrick Z.. Comparable Enhancement of TERS Signals from WSe2 on Chromium and Gold.  United States: N. p., 2020. 
Web.  doi:10.1021/acs.jpcc.0c01298.

Copy to clipboard


                    Krayev, Andrey V., Krylyuk, Sergiy, Ilic, Robert, Hight Walker, Angela, Bhattarai, Ashish, Joly, Alan G., Velicky, Matej, Davydov, Albert, & El-Khoury, Patrick Z.. Comparable Enhancement of TERS Signals from WSe2 on Chromium and Gold.  United States.  https://doi.org/10.1021/acs.jpcc.0c01298

Copy to clipboard


                    Krayev, Andrey V., Krylyuk, Sergiy, Ilic, Robert, Hight Walker, Angela, Bhattarai, Ashish, Joly, Alan G., Velicky, Matej, Davydov, Albert, and El-Khoury, Patrick Z.. Mon .  
"Comparable Enhancement of TERS Signals from WSe2 on Chromium and Gold".  United States.  https://doi.org/10.1021/acs.jpcc.0c01298.  https://www.osti.gov/servlets/purl/1708858.

Copy to clipboard


                    
@article{osti_1708858,

  title        = {Comparable Enhancement of TERS Signals from WSe2 on Chromium and Gold},

  author       = {Krayev, Andrey V. and Krylyuk, Sergiy and Ilic, Robert and Hight Walker, Angela and Bhattarai, Ashish and Joly, Alan G. and Velicky, Matej and Davydov, Albert and El-Khoury, Patrick Z.},

  abstractNote = {Plasmonic tip-sample junctions, at which the incident and scattered optical fields are localized and optimally enhanced, are often exploited to achieve ultrasensitive and highly spatially localized tip-enhanced Raman scattering (TERS). Recent work has demonstrated that the sensitivity and spatial resolution that are required to probe single molecules are attainable in such platforms. In this work, we observe and rationalize comparable TERS from few-layer WSe2 single crystals exfoliated onto Au- and Cr-coated Si substrates, using a plasmonic TERS probe excited with a 638-nm laser. Our experimental observations are supported by finite-difference time-domain simulations that illustrate that the attainable field enhancement factors at the Au-Au and Au-Cr tip-sample nanojunctions are comparable in magnitude. Furthermore, through a combined experimental and theoretical analysis, we propose that besides Au/Ag, several metallic substrates may be used to record bright TERS spectral images.},

  doi          = {10.1021/acs.jpcc.0c01298},

  journal      = {Journal of Physical Chemistry. C},

  number       = 16,

  volume       = 124,

  place        = {United States},

  year         = {2020},

  month        = {4}

}

Copy to clipboard

Journal Article:

Free Publicly Available Full Text

Accepted Manuscript (DOE)

Publisher's Version of Record

https://doi.org/10.1021/acs.jpcc.0c01298

Other availability

Search WorldCat to find libraries that may hold this journal

Save / Share:

Export Metadata

Save to My Library

Works referenced in this record:

Locally enhanced Raman spectroscopy with an atomic force microscope
journal, May 2000

Anderson, Mark S.
Applied Physics Letters, Vol. 76, Issue 21
DOI: 10.1063/1.126546

Nanoscale chemical analysis by tip-enhanced Raman spectroscopy
journal, February 2000

Stöckle, Raoul M.; Suh, Yung Doug; Deckert, Volker
Chemical Physics Letters, Vol. 318, Issue 1-3, p. 131-136
DOI: 10.1016/S0009-2614(99)01451-7

Tip-Enhanced Raman Spectroscopy: Near-Fields Acting on a Few Molecules
journal, May 2012

Pettinger, Bruno; Schambach, Philip; Villagómez, Carlos J.
Annual Review of Physical Chemistry, Vol. 63, Issue 1
DOI: 10.1146/annurev-physchem-032511-143807

Developments in and practical guidelines for tip-enhanced Raman spectroscopy
journal, January 2012

Stadler, Johannes; Schmid, Thomas; Zenobi, Renato
Nanoscale, Vol. 4, Issue 6, p. 1856-1870
DOI: 10.1039/C1NR11143D

Single-Molecule Chemistry with Surface- and Tip-Enhanced Raman Spectroscopy
journal, December 2016

Zrimsek, Alyssa B.; Chiang, Naihao; Mattei, Michael
Chemical Reviews, Vol. 117, Issue 11
DOI: 10.1021/acs.chemrev.6b00552

Tip-enhanced Raman spectroscopy: From concepts to practical applications
journal, August 2016

Jiang, Nan; Kurouski, Dmitry; Pozzi, Eric A.
Chemical Physics Letters, Vol. 659
DOI: 10.1016/j.cplett.2016.06.035

Tip-enhanced Raman spectroscopy for surfaces and interfaces
journal, January 2017

Wang, Xiang; Huang, Sheng-Chao; Huang, Teng-Xiang
Chemical Society Reviews, Vol. 46, Issue 13
DOI: 10.1039/C7CS00206H

Tip-Enhanced Raman Spectroscopy: Technique and Recent Advances
journal, April 2017

Verma, Prabhat
Chemical Reviews, Vol. 117, Issue 9
DOI: 10.1021/acs.chemrev.6b00821

Probing Bilayer Grain Boundaries in Large-Area Graphene with Tip-Enhanced Raman Spectroscopy
journal, December 2016

Park, Kyoung-Duck; Raschke, Markus B.; Atkin, Joanna M.
Advanced Materials, Vol. 29, Issue 7
DOI: 10.1002/adma.201603601

Gated Tunability and Hybridization of Localized Plasmons in Nanostructured Graphene
journal, February 2013

Fang, Zheyu; Thongrattanasiri, Sukosin; Schlather, Andrea
ACS Nano, Vol. 7, Issue 3
DOI: 10.1021/nn3055835

Controlling Subnanometer Gaps in Plasmonic Dimers Using Graphene
journal, October 2013

Mertens, Jan; Eiden, Anna L.; Sigle, Daniel O.
Nano Letters, Vol. 13, Issue 11
DOI: 10.1021/nl4018463

Graphene-Antenna Sandwich Photodetector
journal, June 2012

Fang, Zheyu; Liu, Zheng; Wang, Yumin
Nano Letters, Vol. 12, Issue 7
DOI: 10.1021/nl301774e

Nanoscale Chemical Imaging of Single-Layer Graphene
journal, September 2011

Stadler, Johannes; Schmid, Thomas; Zenobi, Renato
ACS Nano, Vol. 5, Issue 10
DOI: 10.1021/nn2035523

Tip-enhanced Raman spectroscopy of 6H-SiC with graphene adlayers: selective suppression of E1 modes: Tip-enhanced Raman spectroscopy of 6H-SiC with graphene adlayers
journal, September 2009

Domke, Katrin F.; Pettinger, Bruno
Journal of Raman Spectroscopy, Vol. 40, Issue 10
DOI: 10.1002/jrs.2434

Tip-enhanced Raman scattering of graphene: Tip-enhanced Raman scattering of graphene
journal, August 2017

Beams, Ryan
Journal of Raman Spectroscopy, Vol. 49, Issue 1
DOI: 10.1002/jrs.5211

Characterizing unusual metal substrates for gap-mode tip-enhanced Raman spectroscopy: Characterizing unusual metal substrates for gap-mode TERS
journal, November 2012

Stadler, Johannes; Oswald, Benedikt; Schmid, Thomas
Journal of Raman Spectroscopy, Vol. 44, Issue 2
DOI: 10.1002/jrs.4169

Tip-Enhanced Raman Scattering on Bulk MoS ₂ Substrate
journal, March 2017

He, Zhe; Voronine, Dmitri V.; Sinyukov, Alexander M.
IEEE Journal of Selected Topics in Quantum Electronics, Vol. 23, Issue 2
DOI: 10.1109/JSTQE.2016.2611591

Visualizing nanoscale excitonic relaxation properties of disordered edges and grain boundaries in monolayer molybdenum disulfide
journal, August 2015

Bao, Wei; Borys, Nicholas J.; Ko, Changhyun
Nature Communications, Vol. 6, Issue 1
DOI: 10.1038/ncomms8993

The important role of water in growth of monolayer transition metal dichalcogenides
journal, March 2017

Kastl, Christoph; Chen, Christopher T.; Kuykendall, Tevye
2D Materials, Vol. 4, Issue 2
DOI: 10.1088/2053-1583/aa5f4d

Nanoscale Heterogeneities in Monolayer MoSe ₂ Revealed by Correlated Scanning Probe Microscopy and Tip-Enhanced Raman Spectroscopy
journal, January 2018

Smithe, Kirby K. H.; Krayev, Andrey V.; Bailey, Connor S.
ACS Applied Nano Materials, Vol. 1, Issue 2
DOI: 10.1021/acsanm.7b00083

Hybrid Tip-Enhanced Nanospectroscopy and Nanoimaging of Monolayer WSe ₂ with Local Strain Control
journal, March 2016

Park, Kyoung-Duck; Khatib, Omar; Kravtsov, Vasily
Nano Letters, Vol. 16, Issue 4
DOI: 10.1021/acs.nanolett.6b00238

Imaging localized electric fields with nanometer precision through tip-enhanced Raman scattering
journal, January 2017

Bhattarai, A.; El-Khoury, P. Z.
Chemical Communications, Vol. 53, Issue 53
DOI: 10.1039/C7CC02593A

Tip-Enhanced Raman Scattering from Nanopatterned Graphene and Graphene Oxide
journal, May 2018

Bhattarai, Ashish; Krayev, Andrey; Temiryazev, Alexey
Nano Letters, Vol. 18, Issue 6
DOI: 10.1021/acs.nanolett.8b01690

Visualizing surface plasmons with photons, photoelectrons, and electrons
journal, January 2016

El-Khoury, P. Z.; Abellan, P.; Gong, Y.
The Analyst, Vol. 141, Issue 12
DOI: 10.1039/C6AN00308G

Optical dielectric function of gold
journal, December 2012

Olmon, Robert L.; Slovick, Brian; Johnson, Timothy W.
Physical Review B, Vol. 86, Issue 23
DOI: 10.1103/PhysRevB.86.235147

Excited Excitonic States in 1L, 2L, 3L, and Bulk WSe ₂ Observed by Resonant Raman Spectroscopy
journal, August 2014

del Corro, Elena; Terrones, Humberto; Elias, Ana
ACS Nano, Vol. 8, Issue 9
DOI: 10.1021/nn504088g

Demonstrating Photoluminescence from Au is Electronic Inelastic Light Scattering of a Plasmonic Metal: The Origin of SERS Backgrounds
journal, March 2015

Hugall, James T.; Baumberg, Jeremy J.
Nano Letters, Vol. 15, Issue 4
DOI: 10.1021/acs.nanolett.5b00146

Nano-“Squeegee” for the Creation of Clean 2D Material Interfaces
journal, March 2018

Rosenberger, Matthew R.; Chuang, Hsun-Jen; McCreary, Kathleen M.
ACS Applied Materials & Interfaces, Vol. 10, Issue 12
DOI: 10.1021/acsami.8b01224

Visualizing Electric Fields at Au(111) Step Edges via Tip-Enhanced Raman Scattering
journal, October 2017

Bhattarai, Ashish; Joly, Alan G.; Hess, Wayne P.
Nano Letters, Vol. 17, Issue 11
DOI: 10.1021/acs.nanolett.7b04027

Local field enhancement of an infinite conical metal tip illuminated by a focused beam: Local field enhancement of an infinite conical metal tip illuminated by a focused beam
journal, September 2009

Zhang, Weihua; Cui, Xudong; Martin, Olivier J. F.
Journal of Raman Spectroscopy, Vol. 40, Issue 10
DOI: 10.1002/jrs.2439

Similar Records in DOE PAGES and OSTI.GOV collections:

Taking the Plunge: Nanoscale Chemical Imaging of Functionalized Gold Triangles in H2O via TERS

Journal Article Bhattarai, Ashish ; Joly, Alan G. ; Krayev, Andrey V. ; ... - Journal of Physical Chemistry C

We demonstrate fast (0.25 s/pixel) nanoscale chemical imaging in aqueous solution via tip-enhanced Raman scattering (TERS), with sub-15 nm spatial resolution. The substrate consists of 4-mercaptobenzonitrile-functionalized monocrystalline gold triangular platelets immersed in H2O, which we map using a gold-coated AFM probe illuminated using a 633 nm laser source. We find that the recorded TERS images trace the enhanced local optical fields that are sustained towards the edges and corners of the triangles. In effect, we directly map local optical fields of a plasmonic substrate in aqueous solution through molecular TERS. Overall, our described platform and approach may generally be usedmore »« less
https://doi.org/10.1021/acs.jpcc.9b00867
Direct Experimental Evidence of Hot Carrier-Driven Chemical Processes in Tip-Enhanced Raman Spectroscopy (TERS)

Journal Article Wang, Rui ; Li, Jingbai ; Rigor, Joel ; ... - Journal of Physical Chemistry. C

Nanoscale localization of electromagnetic fields using metallic nanostructures can catalyze chemical reactions in their immediate vicinity. Local optical field confinement and enhancement is also exploited to attain single molecule detection sensitivity in surface and tip-enhanced Raman (TER) spectroscopy. In this work reported herein, we observe and investigate the sporadic formation of 4-nitrobenzenethiolate upon TER imaging of a 4-nitrobenzenethiol (4NBT) monolayer on Au(111). Density functional theory (DFT), finite-difference time-domain (FDTD), and finite element method (FEM) calculations together confirm that this chemical reaction does not occur as a result of thermal desorption of the molecule, which requires temperatures in excess of 2100more »« less
Cited by 37
https://doi.org/10.1021/acs.jpcc.9b12002

Full Text Available
Tip-Enhanced Raman Scattering from Nanopatterned Graphene and Graphene Oxide

Journal Article Bhattarai, Ashish ; Krayev, Andrey V. ; Temiryazev, Alexei ; ... - Nano Letters

Tip-enhanced Raman spectroscopy (TERS) is particularly sensitive to analytes residing at plasmonic tip-sample nanojunctions, where the incident and scattered optical fields may be localized and optimally enhanced. However, the enhanced local electric fields in this so-called gap-mode TERS configuration are nominally orthogonal to the sample plane. As such, any given Raman active vibrational Eigenstate needs to have projections (of its polarizability derivative tensor elements) along the sample normal to be detectable via TERS. The faint TERS signals observed from two prototypical systems, namely, pristine graphene and graphene oxide are a classical example of the aforementioned rather restrictive TERS selection rulesmore »« less
https://doi.org/10.1021/acs.nanolett.8b01690
Tip-Enhanced Raman Scattering on Both Sides of the Schrödinger Equation

Journal Article El-Khoury, Patrick Z. - Accounts of Chemical Research

We report historically, molecular spectroscopists have focused their attention to the right-hand side of the Schrödinger equation. Our major goal had and still has to do with determining a (bio)molecular system’s Hamiltonian operator. From a theoretical spectroscopist’s perspective, this entails varying the parameters of a model Hamiltonian until the predicted observables agree with their experimental analogues. In this context, less emphasis has been put on the left-hand side of the equation, where the interplay between a system and its immediate local environment is described. The latter is particularly meaningful and informative in modern applications of optical microscopy and spectroscopy thatmore »« less
https://doi.org/10.1021/acs.accounts.1c00597

Full Text Available
Imaging the Optical Fields of Functionalized Silver Nanowires through Molecular TERS

Journal Article Bhattarai, Ashish ; Crampton, Kevin T. ; Joly, Alan G. ; ... - Journal of Physical Chemistry Letters

We image 4-mercaptobenzonitrile-functionalized silver nanowires (~20 nm diameter) through tipenhanced Raman scattering (TERS). The enhanced local optical field-molecular interactions that govern the recorded hyperspectral TERS images are dissected through hybrid finite-difference time-domain-density functional theory simulations. Our forward simulations illustrate that the recorded spatio-spectral profiles of the chemically functionalized nanowires may be reproduced by accounting for the interaction between orientationally averaged molecular polarizability derivative tensors and enhanced incident/scattered local fields polarized along the tip axis. In effect, we directly map the enhanced optical fields of the nanowire in real space through TERS. The simultaneously recorded atomic force microscopy (AFM) images allowmore »« less
https://doi.org/10.1021/acs.jpclett.8b03324

Similar Records

Title: Comparable Enhancement of TERS Signals from WSe2 on Chromium and Gold

Abstract

Citation Formats

Locally enhanced Raman spectroscopy with an atomic force microscope journal, May 2000

Nanoscale chemical analysis by tip-enhanced Raman spectroscopy journal, February 2000

Tip-Enhanced Raman Spectroscopy: Near-Fields Acting on a Few Molecules journal, May 2012

Developments in and practical guidelines for tip-enhanced Raman spectroscopy journal, January 2012

Single-Molecule Chemistry with Surface- and Tip-Enhanced Raman Spectroscopy journal, December 2016

Tip-enhanced Raman spectroscopy: From concepts to practical applications journal, August 2016

Tip-enhanced Raman spectroscopy for surfaces and interfaces journal, January 2017

Tip-Enhanced Raman Spectroscopy: Technique and Recent Advances journal, April 2017

Probing Bilayer Grain Boundaries in Large-Area Graphene with Tip-Enhanced Raman Spectroscopy journal, December 2016

Gated Tunability and Hybridization of Localized Plasmons in Nanostructured Graphene journal, February 2013

Controlling Subnanometer Gaps in Plasmonic Dimers Using Graphene journal, October 2013

Graphene-Antenna Sandwich Photodetector journal, June 2012

Nanoscale Chemical Imaging of Single-Layer Graphene journal, September 2011

Tip-enhanced Raman spectroscopy of 6H-SiC with graphene adlayers: selective suppression of E1 modes: Tip-enhanced Raman spectroscopy of 6H-SiC with graphene adlayers journal, September 2009

Tip-enhanced Raman scattering of graphene: Tip-enhanced Raman scattering of graphene journal, August 2017

Characterizing unusual metal substrates for gap-mode tip-enhanced Raman spectroscopy: Characterizing unusual metal substrates for gap-mode TERS journal, November 2012

Tip-Enhanced Raman Scattering on Bulk MoS 2 Substrate journal, March 2017

Visualizing nanoscale excitonic relaxation properties of disordered edges and grain boundaries in monolayer molybdenum disulfide journal, August 2015

The important role of water in growth of monolayer transition metal dichalcogenides journal, March 2017

Nanoscale Heterogeneities in Monolayer MoSe 2 Revealed by Correlated Scanning Probe Microscopy and Tip-Enhanced Raman Spectroscopy journal, January 2018

Hybrid Tip-Enhanced Nanospectroscopy and Nanoimaging of Monolayer WSe 2 with Local Strain Control journal, March 2016

Imaging localized electric fields with nanometer precision through tip-enhanced Raman scattering journal, January 2017

Tip-Enhanced Raman Scattering from Nanopatterned Graphene and Graphene Oxide journal, May 2018

Visualizing surface plasmons with photons, photoelectrons, and electrons journal, January 2016

Optical dielectric function of gold journal, December 2012

Excited Excitonic States in 1L, 2L, 3L, and Bulk WSe 2 Observed by Resonant Raman Spectroscopy journal, August 2014

Demonstrating Photoluminescence from Au is Electronic Inelastic Light Scattering of a Plasmonic Metal: The Origin of SERS Backgrounds journal, March 2015

Nano-“Squeegee” for the Creation of Clean 2D Material Interfaces journal, March 2018

Visualizing Electric Fields at Au(111) Step Edges via Tip-Enhanced Raman Scattering journal, October 2017

Local field enhancement of an infinite conical metal tip illuminated by a focused beam: Local field enhancement of an infinite conical metal tip illuminated by a focused beam journal, September 2009

Title: Comparable Enhancement of TERS Signals from WSe₂ on Chromium and Gold

Locally enhanced Raman spectroscopy with an atomic force microscope
journal, May 2000

Nanoscale chemical analysis by tip-enhanced Raman spectroscopy
journal, February 2000

Tip-Enhanced Raman Spectroscopy: Near-Fields Acting on a Few Molecules
journal, May 2012

Developments in and practical guidelines for tip-enhanced Raman spectroscopy
journal, January 2012

Single-Molecule Chemistry with Surface- and Tip-Enhanced Raman Spectroscopy
journal, December 2016

Tip-enhanced Raman spectroscopy: From concepts to practical applications
journal, August 2016

Tip-enhanced Raman spectroscopy for surfaces and interfaces
journal, January 2017

Tip-Enhanced Raman Spectroscopy: Technique and Recent Advances
journal, April 2017

Probing Bilayer Grain Boundaries in Large-Area Graphene with Tip-Enhanced Raman Spectroscopy
journal, December 2016

Gated Tunability and Hybridization of Localized Plasmons in Nanostructured Graphene
journal, February 2013

Controlling Subnanometer Gaps in Plasmonic Dimers Using Graphene
journal, October 2013

Graphene-Antenna Sandwich Photodetector
journal, June 2012

Nanoscale Chemical Imaging of Single-Layer Graphene
journal, September 2011

Tip-enhanced Raman spectroscopy of 6H-SiC with graphene adlayers: selective suppression of E1 modes: Tip-enhanced Raman spectroscopy of 6H-SiC with graphene adlayers
journal, September 2009

Tip-enhanced Raman scattering of graphene: Tip-enhanced Raman scattering of graphene
journal, August 2017

Characterizing unusual metal substrates for gap-mode tip-enhanced Raman spectroscopy: Characterizing unusual metal substrates for gap-mode TERS
journal, November 2012

Tip-Enhanced Raman Scattering on Bulk MoS ₂ Substrate
journal, March 2017

Visualizing nanoscale excitonic relaxation properties of disordered edges and grain boundaries in monolayer molybdenum disulfide
journal, August 2015

The important role of water in growth of monolayer transition metal dichalcogenides
journal, March 2017

Nanoscale Heterogeneities in Monolayer MoSe ₂ Revealed by Correlated Scanning Probe Microscopy and Tip-Enhanced Raman Spectroscopy
journal, January 2018

Hybrid Tip-Enhanced Nanospectroscopy and Nanoimaging of Monolayer WSe ₂ with Local Strain Control
journal, March 2016

Imaging localized electric fields with nanometer precision through tip-enhanced Raman scattering
journal, January 2017

Tip-Enhanced Raman Scattering from Nanopatterned Graphene and Graphene Oxide
journal, May 2018

Visualizing surface plasmons with photons, photoelectrons, and electrons
journal, January 2016

Optical dielectric function of gold
journal, December 2012

Excited Excitonic States in 1L, 2L, 3L, and Bulk WSe ₂ Observed by Resonant Raman Spectroscopy
journal, August 2014

Demonstrating Photoluminescence from Au is Electronic Inelastic Light Scattering of a Plasmonic Metal: The Origin of SERS Backgrounds
journal, March 2015

Nano-“Squeegee” for the Creation of Clean 2D Material Interfaces
journal, March 2018

Visualizing Electric Fields at Au(111) Step Edges via Tip-Enhanced Raman Scattering
journal, October 2017

Local field enhancement of an infinite conical metal tip illuminated by a focused beam: Local field enhancement of an infinite conical metal tip illuminated by a focused beam
journal, September 2009