Related Experiment Video
Updated: Oct 26, 2025
09:57
Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
7.3K
Scouting for strong light-matter coupling signatures in Raman spectra
Wassie Mersha Takele1, Lukasz Piatkowski, Frank Wackenhut
1Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland. jwaluk@ichf.edu.pl.
Physical Chemistry Chemical Physics : PCCP
|July 29, 2021
Summary
Vibrational polaritons, formed by strong light-matter coupling, did not alter Raman scattering in tested molecules. Changes observed were due to surface enhancement effects, not polariton formation.
Area of Science:
- Chemical physics
- Spectroscopy
- Materials science
Background:
- Strong coupling between molecular vibrations and cavity photon modes creates vibrational polaritons, hybrid light-matter states with potential for chemical reactivity control.
- While polaritons are well-studied for IR transmission, their impact on Raman scattering remains largely unexplored.
Purpose of the Study:
- To investigate the influence of vibrational strong coupling on the Raman scattering properties of various molecules.
- To determine if vibrational polaritons can be observed in Raman spectra and alter scattering characteristics.
- To differentiate between effects of strong coupling and other phenomena like surface enhancement on Raman spectra.
Main Methods:
- Formation of vibrational polaritons by coupling molecular vibrations to cavity modes.
- Measurement of IR transmission spectra to confirm polariton formation.
- Analysis of Raman scattering spectra for different molecular systems (benzonitrile, methyl salicylate, polyvinyl acetate) under strong coupling conditions.
- Systematic investigation using cavities with varying layer structures for solid polymer films.
Main Results:
- Polariton states were clearly observed in IR transmission spectra for liquid-phase molecules and a solid polymer film.
- No signatures of polariton states were detected in the Raman spectra of any studied system.
- Alterations in Raman spectra were observed only when a thin silver (Ag) layer was in direct contact with the polymer film.
Conclusions:
- Vibrational strong coupling, while forming observable polaritons in IR spectra, does not inherently alter Raman scattering properties.
- Observed spectral changes in specific configurations are attributable to surface enhancement effects, particularly from metallic layers.
- Distinguishing between true strong coupling effects and surface plasmon-related phenomena is crucial in hybrid light-matter system studies.
Related Concept Videos
01:20Raman Spectroscopy: Overview
804
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...
804
01:26Raman Spectroscopy Instrumentation: Overview
604
A conventional Raman spectrophotometer includes a laser source, a sample holding system, a wavelength selector, and a detector.
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...
604
01:08NMR Spectroscopy: Spin–Spin Coupling
2.2K
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...
2.2K
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.2K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.2K
01:27¹H NMR: Long-Range Coupling
2.1K
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
2.1K
01:13¹H NMR: Complex Splitting
1.4K
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
1.4K