Related Experiment Video
Updated: Jun 4, 2026
10:03
Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
Time-domain SFG spectroscopy using mid-IR pulse shaping: practical and intrinsic advantages
Jennifer E Laaser1, Wei Xiong, Martin T Zanni
1Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
The Journal of Physical Chemistry. B
|March 4, 2011
Summary
New time-domain sum-frequency generation (SFG) spectroscopy techniques enhance surface science analysis. This advanced method reveals molecular structures at interfaces with greater accuracy than traditional frequency-domain approaches.
Area of Science:
- Surface science
- Molecular spectroscopy
- Interface analysis
Background:
- Sum-frequency generation (SFG) spectroscopy is vital for studying molecular interfaces.
- It provides infrared transition frequencies and line shapes to probe molecular structure and environment.
- Existing frequency-domain methods have limitations in signal throughput, resolution, and accuracy.
Purpose of the Study:
- To adapt multidimensional spectroscopy techniques for SFG spectroscopy.
- To implement advanced methods for improved spectral analysis and data acquisition.
- To demonstrate the advantages of time-domain SFG spectroscopy.
Main Methods:
- Balanced heterodyne detection to eliminate scatter and background noise.
- Mid-infrared (mid-IR) pulse shaping for precise control of pump pulse phase and delay.
- Time-domain data collection utilizing Fourier transform techniques.
Main Results:
- Balanced heterodyne detection successfully removed background signals.
- Mid-IR pulse shaping enabled phase cycling and background subtraction.
- Time-domain SFG spectroscopy revealed an inhomogeneous structural distribution in an aryl isocyanide on gold system, unresolved by previous methods.
- Demonstrated advantages in signal throughput, frequency resolution, and line shape accuracy.
Conclusions:
- Time-domain SFG spectroscopy offers significant improvements over frequency-domain methods.
- The technique provides more accurate and detailed insights into molecular interfaces.
- Advanced pulse shaping and detection methods enable new experimental possibilities and enhanced spectral accuracy.
Related Concept Videos
01:11Applications of IR Spectroscopy: Overview
The non-destructive nature and ability to provide valuable chemical information make IR spectroscopy a versatile technique with broad applications in various scientific and industrial fields. IR spectroscopy is commonly used to identify and characterize organic and inorganic compounds. It provides information about the functional groups present in a molecule and the bonding between atoms. This helps in the structural elucidation of compounds during organic synthesis, pharmaceutical research,...
01:25IR Spectrometers
There are two main infrared (IR) spectrophotometers: dispersive IR spectrometers and Fourier transform infrared (FTIR) spectrometers. In a dispersive IR spectrometer, a beam of infrared radiation produced by a hot wire is divided into two parallel equal-intensity beams using mirrors. One beam passes through the sample, while another is a reference beam. The beams then move through the monochromator, which separates the radiations into a continuous spectrum of different frequencies. The...
01:09Infrared (IR) Spectroscopy: Overview
When electromagnetic radiation passes through a material, atoms or molecules transition from a lower to a higher energy state by absorbing radiation corresponding to the energy difference between the two states. The absorption of infrared (IR) radiation causes transitions between vibrational energy levels in a molecule. Therefore, IR spectroscopy is a useful analytical tool for determining the molecular structure of molecules.
Different compounds display unique properties due to their...
Different compounds display unique properties due to their...
01:24IR Spectroscopy: Molecular Vibration Overview
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...
01:17NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences
A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a radio frequency pulse along the x-axis, the nuclei absorb energy corresponding to their Larmor frequencies and achieve resonance. This shifts the net magnetization vector from the z-axis toward the transverse plane. This angle of rotation of the magnetization vector, or the flip angle, is proportional to the duration and intensity of the pulse.
01:03IR Frequency Region: Fingerprint Region
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 C=O, C=N, and C=C occur between 1600–1850 cm−1.
The...
The...