Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

2D atomic crystals probe: how hot it is in a plasmonic 'hotspot'

05.09.2018

Plasmonic field enhancement is the cornerstone of a wide range of applications ranging from surface enhance spectroscopy, sensing, and nonlinear optics to light harvesting. The most intense plasmonic fields usually appear within narrow gaps('hotspot') between adjacent metallic nanostructures, especially when the separation goes down to subnanometer scale. However, experimentally probing the plasmonic fields in such a tiny volume still challenges the nanofabrication and detection techniques.

Measuring surface-enhanced Raman scattering (SERS) signal from a probe inside the nanogap region is a promising avenue to do that, but it still faces several intractable issues: (i) how to create a width-controllable subnanometer gap with well-defined geometry, (ii) how to insert the nanoprobe into such narrow gap, and more importantly, (iii) how to control the alignment of the probe with respect to the strongest plasmonic field component.


Conventional SERS probes using molecule are hard to control while a 2D material is perfect probe to the plasmonic fields in a nanogap.

Credit: Wen Chen, Shunping Zhang, Meng Kang, Weikang Liu, Zhenwei Ou, Yang Li, Yexin Zhang, Zhiqiang Guan, Hongxing Xu, Probing the limits of plasmonic enhancement using a two-dimensional atomic crystal probe, Light: Science and Applications, doi: 10.1038/s41377-018-0056-3.

What's more, the excitation laser should match with the plasmonic resonances in both wavelength and polarization, to get the maximum plasmonic enhancement. These requirements are difficult to satisfy simultaneously in traditional SERS using molecules as probe.

To overcome all these limitations, a research group led by Shunping Zhang and Hongxing Xu at Wuhan University, China, has developed a quantitative SERS technique to probe the maximum plasmonic fields before effects such as electron tunneling become dominant.

The researchers turned to molybdenum disulfide (MoS2)- a graphene-like, two-dimensional atomic layer to tune the distance between a gold nanoparticle and a smooth gold film. For the first time, the plasmonic near-field components in vertical and horizontal directions within atom-thick plasmonic nanocavities were quantitatively measured by using tiny flakes of two-dimensional atomic crystals as probes.

In their configuration, the researchers can ensure that the probe filled in the gap has a well-defined lattice orientation such that the lattice vibrations are precisely aligned with the plasmonic field components.

These lattice probes are free of optical bleaching or molecule hopping (in/out of the hotspot) as in traditional SERS experiments. They achieved the quantitative extraction of plasmonic fields in the nanogap by measuring the SERS intensity from the out-of-plane and in-plane phonon modes of the MoS2.

The robustness of the 2D atomic crystal as SERS probes promote SERS to be a quantitative analytic tool instead of a qualitative one in most previous applications.

Also, these unique designs could provide an important guide for further understanding quantum mechanical effects as well as plasmon-enhanced photon-phonon interactions and promoting relevant new applications, such as quantum plasmonics and nanogap optomechanics.

Yaobiao Li | EurekAlert!
Further information:
http://dx.doi.org/10.1038/s41377-018-0056-3

More articles from Physics and Astronomy:

nachricht Statistical inference to mimic the operating manner of highly-experienced crystallographer
18.09.2019 | Japan Science and Technology Agency

nachricht Scientists create fully electronic 2-dimensional spin transistors
18.09.2019 | University of Groningen

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Happy hour for time-resolved crystallography

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Hamburg and the European Molecular Biology Laboratory (EMBL) outstation in the city have developed a new method to watch biomolecules at work. This method dramatically simplifies starting enzymatic reactions by mixing a cocktail of small amounts of liquids with protein crystals. Determination of the protein structures at different times after mixing can be assembled into a time-lapse sequence that shows the molecular foundations of biology.

The functions of biomolecules are determined by their motions and structural changes. Yet it is a formidable challenge to understand these dynamic motions.

Im Focus: Modular OLED light strips

At the International Symposium on Automotive Lighting 2019 (ISAL) in Darmstadt from September 23 to 25, 2019, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, a provider of research and development services in the field of organic electronics, will present OLED light strips of any length with additional functionalities for the first time at booth no. 37.

Almost everyone is familiar with light strips for interior design. LED strips are available by the metre in DIY stores around the corner and are just as often...

Im Focus: Tomorrow´s coolants of choice

Scientists assess the potential of magnetic-cooling materials

Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....

Im Focus: The working of a molecular string phone

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.

This time-lapse sequence of structures reveals dynamic motions as a fundamental element in the molecular foundations of biology.

Im Focus: Milestones on the Way to the Nuclear Clock

Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.

If you want to build the most accurate clock in the world, you need something that "ticks" very fast and extremely precise. In an atomic clock, electrons are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Society 5.0: putting humans at the heart of digitalisation

10.09.2019 | Event News

Interspeech 2019 conference: Alexa and Siri in Graz

04.09.2019 | Event News

AI for Laser Technology Conference: optimizing the use of lasers with artificial intelligence

29.08.2019 | Event News

 
Latest News

Stroke patients relearning how to walk with peculiar shoe

18.09.2019 | Innovative Products

Statistical inference to mimic the operating manner of highly-experienced crystallographer

18.09.2019 | Physics and Astronomy

Scientists' design discovery doubles conductivity of indium oxide transparent coatings

18.09.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>