Related Experiment Video
Updated: Jul 15, 2026
09:57
Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
Pressure jump relaxation setup with IR detection and millisecond time resolution
Martin Schiewek1, Marina Krumova, Günter Hempel
1Faculty of Chemistry and Physics, Institute of Chemistry, Martin-Luther-Universität Halle-Wittenberg, Mühlpforte 1, Halle (Saale), Germany.
The Review of Scientific Instruments
|May 5, 2007
Summary
A new instrument combines Fourier transform infrared (FTIR) spectroscopy with a pressure jump technique for studying rapid kinetic processes. This method analyzes molecular changes following pressure changes, offering insights into dynamic systems.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Biophysical Chemistry
Background:
- Kinetic processes are crucial for understanding chemical and biological systems.
- Traditional methods may lack the speed or resolution to capture rapid molecular events.
- Pressure perturbation techniques offer unique insights into systems with volume changes.
Purpose of the Study:
- To develop and validate a novel instrument for time-resolved kinetic studies using Fourier transform infrared (FTIR) spectroscopy coupled with a pressure jump system.
- To enable the investigation of rapid molecular processes occurring within milliseconds after a significant pressure change.
- To demonstrate the utility of this technique for studying cooperative transitions in condensed phases.
Main Methods:
- An instrument was designed integrating a high-pressure liquid chromatography pump for pressure generation (up to 100 bars) with FTIR spectroscopy.
- A flexible membrane separated the liquid sample from the water-based pressure transducing medium.
- Rapid pressure jumps (4 ms decay time) were achieved using electromagnetic switching valves, coupled with FTIR's rapid scan mode for millisecond time-resolved spectral acquisition.
- Computer control integrated all components for precise experimental execution.
Main Results:
- The instrument successfully enabled time-resolved FTIR spectroscopy following pressure jumps.
- The kinetics of a phase transition in an aqueous phospholipid dispersion were successfully measured, demonstrating the system's capability.
- The study presented initial results on the phase transition between two lamellar phases, highlighting the method's sensitivity to cooperative phenomena.
Conclusions:
- The developed instrument provides a powerful tool for studying rapid kinetic processes, particularly those involving volume changes.
- This combined FTIR spectroscopy and pressure jump relaxation technique is applicable to a wide range of systems exhibiting cooperative transitions.
- The method opens new avenues for investigating dynamic molecular behavior in complex systems with high temporal resolution.
Related Concept Videos
01:27Fast Reactions
Fast reactions occurring in times shorter than the time needed to mix reactants pose a unique challenge for investigation. In a liquid-phase continuous-flow system, reactants A and B are swiftly pushed into the mixing chamber, where mixing occurs within 1 ms. The reaction mixture then flows through an observation tube, and one measures light absorption to determine species concentrations at various points of the tube. This method is most appropriate when relatively large volumes of reactants...
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.
01:13Special considerations while measuring pulse
Assessing a patient's pulse is a fundamental skill in healthcare, but certain situations require special attention:
01:24IR Frequency Region: X–H Stretching
In IR spectroscopy, signals produced by the X−H bonds (such as C−H, O−H, or N−H) can be observed in the frequency range of 2700–4000 cm–1. The C−H stretching vibration forms sharp bands in the region 2850–3000 cm–1. The presence of the O−H stretching vibration leads to the forming of an absorption band in the frequency range 3650–3200 cm−1. At the same time, N−H stretching can be confirmed by absorption bands in the 3500–3100 cm−1 range. Even though both O−H and N−H bonds vibrate at a similar...
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...