Related Experiment Video
Updated: Jun 19, 2025
12:11
Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
8.2K
A Vacuum Ultraviolet Photoionization Mass Spectrometry and Density Functional Calculation Study of Formic Acid-Water
Amit Daniely1, Anna Wannenmacher2, Nevo Levy1
1The Fritz Haber Center for Molecular Dynamics, Department of Chemistry, The Hebrew University, Jerusalem 9190501, Israel.
The Journal of Physical Chemistry. A
|July 24, 2024
Summary
Formic acid and water clusters were studied using mass spectrometry and calculations. Specific cluster compositions showed enhanced stability, indicating unique cyclic structures are most stable.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Computational Chemistry
Background:
- The interaction between formic acid and water is crucial in many chemical processes.
- Understanding these interactions at a molecular level is key to controlling chemical reactions.
Purpose of the Study:
- To investigate the structure and stability of formic acid-water clusters.
- To identify specific cluster compositions with enhanced stability.
Main Methods:
- Vacuum-ultraviolet photoionization mass spectrometry was used to analyze cluster formation.
- Density functional calculations were employed to model cluster structures and stability.
Main Results:
- Protonated formic acid-water clusters were identified as the major products.
- Enhanced intensities were observed for clusters with specific formic acid to water ratios (e.g., FA1W5H+, FA2W4H+).
- Calculations revealed cyclic arrangements with enclosed molecules as the most stable structures.
Conclusions:
- Specific compositions of formic acid-water clusters exhibit unique stability.
- Cyclic structures play a significant role in the stability of these clusters.
- Fragmentation pathways can be influenced by cluster size and composition.
Related Concept Videos
01:28IR and UV–Vis Spectroscopy of Carboxylic Acids
3.9K
In IR spectroscopy of carboxylic acids, the C=O bond shows a characteristic band between 1710 and 1760 cm⁻¹, and the O–H bond exhibits a broad band between 2500 and 3300 cm⁻¹.
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency,...
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency,...
3.9K
01:01Mass Spectrometry: Carboxylic Acid, Ester, and Amide Fragmentation
1.2K
The fragmentation patterns observed for compounds such as carboxylic acids, esters, and amides in the mass spectra include ⍺-cleavage and McLafferty rearrangement. Fragmentation by ⍺-cleavage preferentially occurs at the carbon-carbon bond at the ⍺-position next to the carboxylic group to generate a neutral radical and a cation. Long chain compounds with hydrogen at their γ-carbon undergo McLafferty rearrangement to give a radical cation and a neutral alkene.
For example,...
For example,...
1.2K
01:24Mass Spectrum: Interpretation
1.2K
An unknown compound can be established by identifying the molecular ion peak in the mass spectrum. The molecular ion peak is often weak or absent due to the predominance of fragmentation in high-energy electron beams. In such cases, a low-energy electron beam can be used to scan the spectrum to enhance the intensity of the molecular ion peak. Additionally, chemical ionization, field ionization, and desorption ionization spectra are used to obtain a relatively intense molecular ion peak.
To...
To...
1.2K
01:03Mass Spectrometry: Alcohol Fragmentation
3.4K
Alcohols (R-OH) ionize to lose one non-bonded electron from the oxygen atom, forming molecular ions. Due to their tendency to fragment rapidly, the intensity of the molecular ion peak in the mass spectrum is weak or sometimes absent. The fragmentation patterns for alcohols occur in two ways, i.e. ⍺-cleavage and dehydration. During ⍺-cleavage, the bond at the ⍺-position adjacent to the hydroxyl group cleaves to give a resonance-stabilized cation and a radical. However,...
3.4K
01:25Atomic Absorption Spectroscopy: Atomization Methods
394
Atomic Absorption Spectroscopy (AAS) atomizes samples through flame atomization or electrothermal atomization. Flame atomization typically involves a nebulizer and spray chamber assembly to combine the sample with a fuel–oxidant mixture, creating a fine aerosol mist that enters a burner. Typically, the fuel and oxidant are combined in an approximately stoichiometric ratio. However, for atoms that are easily oxidized, a fuel-rich mixture may be more advantageous. Only about 5% of the...
394
01:26Spectroscopy of Carboxylic Acid Derivatives
2.3K
Infrared spectroscopy is primarily used to determine the types of bonds and functional groups. In carboxylic acid derivatives, a typical carbonyl bond absorption is observed around 1650–1850 cm−1. For esters, the absorption is recorded at around 1740 cm−1, while acid halides show the absorption at about 1800 cm−1. Another acid derivative, the acid anhydrides, exhibit two carbonyl absorption around 1760 cm−1 and 1820 cm−1, arising from the symmetrical and...
2.3K