Related Experiment Video
Updated: May 28, 2026
07:49
On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes
Published on: August 5, 2016
Elastic and inelastic low-energy electron collisions with pyrazine
Zdeněk Mašín1, Jimena D Gorfinkiel
1Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom. z.masin@open.ac.uk
The Journal of Chemical Physics
|October 21, 2011
Summary
This study details electron scattering calculations on pyrazine, confirming known resonances and discovering new core-excited states. Findings offer guidance for selecting accurate computational models in electron-molecule collision research.
Area of Science:
- Theoretical chemistry
- Atomic and molecular physics
- Quantum scattering theory
Background:
- Pyrazine is a key nitrogen-containing heterocyclic molecule with significant implications in various chemical and biological processes.
- Understanding electron interactions with pyrazine is crucial for fields like atmospheric chemistry and materials science.
- Previous studies have identified specific low-lying resonances, but a comprehensive understanding of higher energy states and scattering dynamics remains incomplete.
Purpose of the Study:
- To perform ab-initio scattering calculations for electron collisions with pyrazine using the R-matrix method.
- To investigate and characterize both known and previously undiscovered resonance states in electron-pyrazine scattering.
- To analyze the energy dependence of differential cross sections and provide recommendations for computational modeling.
Main Methods:
- Utilized the R-matrix method for ab-initio scattering calculations.
- Employed various levels of approximation to assess model sensitivity.
- Calculated differential cross sections across a range of electron impact energies.
Main Results:
- Confirmed the existence and properties of three well-established π∗ shape resonances in electron-pyrazine scattering.
- Identified numerous core-excited resonances at energies above 4.8 eV and determined their probable parent electronic states.
- Observed significant sensitivity of differential cross sections to the chosen scattering model, particularly at lower electron energies.
Conclusions:
- The study provides a detailed theoretical investigation of electron collisions with pyrazine.
- New core-excited resonances were identified, expanding the understanding of pyrazine's electronic structure and scattering behavior.
- Recommendations are made for selecting appropriate scattering models to accurately describe electron-molecule interactions with targets like pyrazine.
Related Concept Videos
01:25Basicity of Heterocyclic Aromatic Amines
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
01:15Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...
01:17Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals
Ideally, an unpaired electron shows a single peak in the EPR spectrum due to the transition between the two spin energy states. However, coupling interactions can occur between the spins of the unpaired electron and any neighboring spin-active nuclei. This hyperfine coupling results in hyperfine splitting, where the EPR signal is split into multiplets. The signals split into 2nI + 1 peaks, where n is the number of equivalent nuclei and I is the nuclear spin. These splitting patterns provide...
00:53Mass Spectrometry: Alkyne Fragmentation
The fragmentation of alkynes preferentially occurs at the carbon–carbon bond between the α and β carbon of the alkyne bond to generate a 3-propynyl cation (or propargyl cation). In terminal alkynes, there is the only type of fragmentation that yields the 3-propynyl cation. The unsubstituted 3-propynyl cation exhibits a peak at a mass-to-charge ratio of 39. In internal alkynes, the 3-propynyl cation is substituted. For example, 2-pentyne fragments into methyl-substituted 3-propynyl cation, which...
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as annulenes. In...
01:20Mass Spectrometry: Molecular Fragmentation Overview
The ionization of a molecule into a molecular ion inside the mass spectrometer causes instability in the molecule's structure due to the loss of an electron. This eventually leads to the fragmentation or breaking of some bonds in the molecule. The fragmentation occurs predominantly at specific bonds to yield relatively stable fragments.
One type of fragmentation pattern is the cleavage of a single bond in the molecular ion. The cleavage leads to a radical and a cation. The cleavage can occur at...
One type of fragmentation pattern is the cleavage of a single bond in the molecular ion. The cleavage leads to a radical and a cation. The cleavage can occur at...