Related Experiment Video
Updated: Apr 4, 2026
10:37
Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
11.9K
Rotation of methane molecules in dimers and small clusters
Hiromichi Hoshina1, Dmitri Skvortsov1, Mikhail N Slipchenko1
1Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA.
The Journal of Chemical Physics
|September 3, 2015
Summary
Researchers studied methane molecule rotation in small clusters using infrared laser spectroscopy. Spectra revealed internal rotation and anisotropic intermolecular interactions in methane dimers, aligning with theoretical models.
Area of Science:
- Physical Chemistry
- Molecular Spectroscopy
- Quantum Chemistry
Background:
- Understanding molecular interactions is crucial in physical chemistry.
- Methane clusters provide a model system for studying intermolecular forces.
Purpose of the Study:
- To investigate the internal rotation of methane molecules within small clusters.
- To analyze the effects of intermolecular interactions on methane cluster spectra.
Main Methods:
- Formation of methane clusters in helium droplets at 0.38 K.
- Infrared laser spectroscopy targeting the CH4 ν3 vibration (~3030 cm⁻¹).
Main Results:
- Observed well-resolved spectral structures attributed to internal molecular rotation.
- Identified characteristic line splitting in methane dimer spectra due to anisotropic intermolecular forces.
- Achieved quantitative agreement between experimental splitting magnitudes and theoretical potentials.
Conclusions:
- The study successfully characterized internal rotation in methane clusters.
- Experimental findings validate theoretical models of anisotropic intermolecular interactions in methane dimers.
Related Concept Videos
02:18Conformations of Ethane and Propane
19.6K
In an organic molecule, free rotation about the carbon-carbon single bond results in energetically different conformers of the molecule. Due to this rotation, called the internal rotation, ethane has two major conformations — staggered and eclipsed.
Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered...
Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered...
19.6K
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
1.4K
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
1.4K
03:24Hybridization of Atomic Orbitals I
69.4K
The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...
69.4K
02:06Newman Projections
24.3K
Different notations are used to represent the three-dimensional structure of molecules on two-dimensional surfaces. One of the most commonly used representations is the dash-wedge formula. The dashed wedges, solid wedges, and the plane lines indicate the groups situated behind the plane, coming out of the plane, and in the plane, respectively.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as...
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as...
24.3K
01:27Inductive Effects on Chemical Shift: Overview
2.5K
The protons in unsubstituted alkanes are strongly shielded with chemical shifts below 1.8 ppm. Methine, methylene, and methyl protons appear at approximately 1.7, 1.2 and 0.7 ppm, while the proton signal from methane appears at 0.23 ppm. An electronegative substituent, such as chlorine, withdraws the electron density from the protons, increasing their chemical shift. Progressive substitution of the hydrogens in methane by chlorine shifts the proton signals increasingly downfield, to 3.05 ppm in...
2.5K
01:08Spin–Spin Coupling Constant: Overview
1.6K
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
1.6K