Related Experiment Video
Updated: Jun 26, 2025
08:51
Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers
Published on: August 18, 2017
10.3K
Coherence mapping to identify the intermediates of multi-channel dissociative ionization
Jacob Stamm1, Sung Kwon1, Shawn Sandhu1
1Department of Chemistry, Michigan State University, S Shaw Ln, East Lansing, MI, 48824, USA.
Communications Chemistry
|May 9, 2024
Summary
Ultrafast strong-field ionization reveals coherent oscillations in product ion yields, acting as spectroscopic signatures to identify short-lived intermediates and fragmentation mechanisms in mass spectrometry.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Spectroscopy
Background:
- Understanding radical cation fragmentation mechanisms is crucial for predicting mass spectra.
- Identifying short-lived intermediates in multi-channel processes remains a challenge.
Purpose of the Study:
- To elucidate the formation mechanisms and identify intermediates of ultrafast radical cation fragmentation.
- To demonstrate the utility of femtosecond time-resolved product ion yield oscillations as spectroscopic signatures.
Main Methods:
- Ultrafast strong-field ionization of endo-dicyclopentadiene.
- Femtosecond time-resolved detection of product ion yields.
- Ab initio calculations to identify vibrational modes of intermediates.
Main Results:
- Coherent oscillations observed in femtosecond time-dependent product ion yields.
- Vibrational frequencies of intermediates are mapped onto product ions.
- Stepwise and concerted fragmentation pathways of the dicyclopentadiene ion confirmed.
Conclusions:
- Femtosecond dynamics tracking of product ions provides insights into reaction mechanisms.
- Spectroscopic signatures from ion oscillations identify specific intermediates.
- The retro-Diels Alder reaction mechanism is further elucidated.
Related Concept Videos
01:19Mass Analyzers: Common Types
598
The quadrupole mass analyzer consists of four cylindrical metal rods arranged in a diamond carrying a DC voltage and a radio-frequency AC voltage. The motion of ions through the quadrupole depends on the field strength, causing only ions of a certain m/z to resonate successfully and strike the detector at a given field strength. Though the transmission rate for these analyzers is high, the exact elemental composition of the sample is not determined because of low resolution; however, they are...
598
01:21Tandem Mass Spectrometry
974
Tandem mass spectrometry is a technique that uses multiple mass analyzers in series to obtain a higher selectivity and signal-to-noise ratio for the analyte. Instruments with multiple analyzers separated by an interaction cell enable secondary fragmentation and selected study of the fragment ions.
Secondary fragmentations occur in the interaction cell and can be induced by various factors. Fragmentation induced by collision with inert gases, such as N2, Ar, He, etc., is called collision-induced...
Secondary fragmentations occur in the interaction cell and can be induced by various factors. Fragmentation induced by collision with inert gases, such as N2, Ar, He, etc., is called collision-induced...
974
01:21Chemical Ionization (CI) Mass Spectrometry
728
The molecular ion peak of a molecule in the mass spectrum provides vital information for molecular identification. However, conventional electron impact ionization can lead to the rapid dissociation of some molecular ions before they reach the detector. A milder ionization method is required to increase the lifetime of such ionized analyte molecules. Chemical ionization (CI) is a gas-phase protonation reaction useful for mass-analyzing analyte molecules that are easily protonated to yield the...
728
01:13Mass Analyzers: Overview
655
The mass analyzer is a crucial component of the mass spectrometer. In the ionization chamber, the vaporized sample is bombarded with a high-energy electron beam to generate a radical cation and further fragment into neutral molecules, radicals, and cations. A series of negatively charged accelerator plates accelerate the cations into the mass analyzer. The mass analyzer separates ions according to their mass-to-charge (m/z) ratios and then directs them to the detector. The common types of mass...
655
01:21Mass Spectrometry: Complex Analysis
760
Mass spectrometry is an important technique for the identification of pure compounds. However, it has some limitations for the analysis of complex mixtures, often due to excessive fragmentation making the spectrum too complicated to decipher. Mass spectrometry can be combined with suitable separation methods in sequence, forming hyphenated methods, which are useful in the analysis of complex mixtures.
GC–MS is a powerful hyphenated method commonly used in forensics and environmental...
GC–MS is a powerful hyphenated method commonly used in forensics and environmental...
760
01:20Inductively Coupled Plasma-Mass Spectrometry (ICP-MS): Interferences
449
Inductively coupled plasma–mass spectrometry (ICP–MS) is a highly selective and sensitive technique for accurate elemental analysis. Though the analysis of ICP–MS mass spectra is comparatively straightforward, it is affected by spectroscopic and non-spectroscopic interferences. Spectroscopic interferences arise when the plasma contains ionic species with an m/z value the same as the analyte ion. Spectroscopic interference can be categorized as isobaric, polyatomic ions, and...
449