Related Experiment Video
Updated: Jun 4, 2025
07:44
Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems
Published on: April 28, 2016
15.0K
Polarisation-dependent Raman enhancement in hexagonal boron nitride membranes
Jakub Rogoża1, Johannes Binder1, Kirill V Voronin2
1University of Warsaw, Faculty of Physics, Pasteura 5, 02-093 Warsaw, Poland.
Nanoscale
|December 24, 2024
Summary
This study introduces a novel microcavity structure using hexagonal boron nitride (h-BN) to enhance Raman spectroscopy signals for 2D materials, avoiding metal nanoparticles.
Area of Science:
- Materials Science
- Spectroscopy
- Nanotechnology
Background:
- Raman spectroscopy is crucial for analyzing materials but suffers from low signal-to-noise ratios with ultrathin and 2D materials.
- Surface-enhanced Raman spectroscopy (SERS) using metallic nanoparticles is a common but metal-dependent solution.
Purpose of the Study:
- To develop a metal-free approach for enhancing Raman signals of 2D materials.
- To demonstrate a microcavity structure utilizing hexagonal boron nitride (h-BN) for signal enhancement.
Main Methods:
- Fabrication of a microcavity structure with an h-BN membrane spanning an air-filled trench in germanium.
- Characterization of Raman signal enhancement in h-BN and transferred graphene layers.
- Numerical simulations of electric field intensity within the cavity.
Main Results:
- Achieved a ~10-fold, polarization-dependent Raman signal enhancement for h-BN.
- Demonstrated that the enhancement effect extends to graphene layers on the h-BN membrane.
- Observed good agreement between experimental results and simulations.
Conclusions:
- The h-BN microcavity provides a facile, metal-free method for enhancing Raman signals of 2D materials and heterostructures.
- This approach offers new possibilities for Raman spectroscopy of 2D crystals without relying on metallic nanoparticles.
Related Concept Videos
01:20Raman Spectroscopy: Overview
305
The underlying principle of Raman spectroscopy is based on the interaction between light and matter, specifically molecules' inelastic scattering of photons. When a monochromatic beam of light, typically from a laser source, interacts with a sample, most scattered light has the same frequency as the incident light. This is known as Rayleigh scattering.
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and...
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and...
305
02:36Regioselectivity and Stereochemistry of Hydroboration
8.0K
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
8.0K
01:29Potential Due to a Polarized Object
365
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...
365
03:24Hybridization of Atomic Orbitals I
46.5K
The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...
46.5K
03:37Molecular Shape and Polarity
59.6K
Dipole Moment of a Molecule
59.6K
01:27π Electron Effects on Chemical Shift: Overview
1.0K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.0K