Related Experiment Video
Updated: Dec 9, 2025
09:57
Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
7.5K
Sum-Frequency Signals in 2D-Terahertz-Terahertz-Raman Spectroscopy
Griffin Mead1, Haw-Wei Lin1, Ioan-Bogdan Magdău1
1Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
The Journal of Physical Chemistry. B
|September 8, 2020
Summary
Halogenated methane (HM) two-dimensional terahertz-terahertz-Raman (2D-TTR) spectra depend on instrument response and molecular coherences. Improved experiments and a new model quantitatively reproduce these complex 2D-TTR signals.
Area of Science:
- Molecular spectroscopy
- Quantum dynamics
- Terahertz spectroscopy
Background:
- Two-dimensional terahertz-terahertz-Raman (2D-TTR) spectroscopy probes molecular dynamics.
- Understanding the instrument response function (IRF) is crucial for spectral interpretation.
- Halogenated methanes (HMs) serve as model systems for studying molecular vibrations.
Purpose of the Study:
- To elucidate the factors determining halogenated methane (HM) 2D-TTR spectra.
- To improve the resolution and dynamic range of 2D-TTR measurements.
- To develop a theoretical model for quantitatively reproducing 2D-TTR signals.
Main Methods:
- Advanced terahertz (THz) pulse characterization.
- High-resolution 2D-TTR spectroscopy experiments.
- Development of a reduced density matrix model incorporating sum-frequency pathways.
Main Results:
- 2D-TTR spectra are governed by the instrument response function (IRF) and molecular coherences.
- Experimental enhancements led to improved spectral resolution and dynamic range.
- Sum-frequency excitations convolved with the IRF accurately reproduce experimental 2D-TTR signals.
Conclusions:
- A new theoretical model fully supports the reinterpretation of 2D-TTR spectra.
- The study provides a quantitative understanding of HM 2D-TTR spectral features.
- This work advances the application of 2D-TTR spectroscopy in molecular dynamics studies.
Related Concept Videos
01:20Raman Spectroscopy: Overview
1.1K
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...
1.1K
01:26Raman Spectroscopy Instrumentation: Overview
843
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...
843
01:03IR Frequency Region: Fingerprint Region
1.7K
IR spectra are divided into two main regions: the diagnostic region and the fingerprint region. The diagnostic region of the spectrum lies above 1500 cm−1. The absorptions resulting from single-bond vibrations of the N–H, C–H, and O–H stretch at higher wavenumbers and appear on the left side of the spectrum. The stretching absorptions of the C≡C and C≡N occur between 2100–2300 cm−1. In contrast, those arising from stretching absorptions of the...
1.7K
01:12Two-Dimensional (2D) NMR: Overview
1.2K
The 1D NMR spectrum of large and complex molecules like natural products has complicated splitting patterns and overlapping signals, which can be easily interpreted using 2-dimensional (2D) NMR. Unlike 1D NMR, 2D NMR has two frequency axes that provide the coupling information between the nucleus A and nucleus B in a molecule. The process from which 2D spectra are obtained has four steps.
The first step is the preparation period, during which nucleus A is excited with a radiofrequency pulse....
The first step is the preparation period, during which nucleus A is excited with a radiofrequency pulse....
1.2K
01:192D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)
1.2K
Heteronuclear single-quantum correlation spectroscopy (HSQC) is a 2D NMR technique that reveals one-bond correlations between hydrogen and a heteronucleus. The HSQC experiment is similar to the heteronuclear correlation experiment (HETCOR) but is more sensitive. In the HSQC spectrum, the proton chemical shift is plotted on the horizontal F2 axis, while the 13C chemical shift is plotted on the vertical F1 axis. The corresponding proton and 13C spectra are also shown. The HSQC contour plot does...
1.2K
01:24IR Spectroscopy: Molecular Vibration Overview
4.1K
When Infrared (IR) radiation passes through a covalently bonded molecule, the bonds transition from lower to higher vibrational levels. The fundamental vibrational motions that result in infrared absorption can be classified as stretching or bending vibrations.
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
4.1K