Related Experiment Video
Updated: Aug 11, 2026
09:26
Cellular Lipid Extraction for Targeted Stable Isotope Dilution Liquid Chromatography-Mass Spectrometry Analysis
Published on: November 17, 2011
Isotopic replacement in ionic systems: the 4He2+ + 3He-->3He 4He+ + 4He reaction
Enrico Bodo1, Manuel Lara, Franco A Gianturco
1Department of Chemistry, University of Rome La Sapienza, Piazzale A. Moro 5, 00185 Rome, Italy.
The Journal of Chemical Physics
|February 8, 2006
Summary
Quantum dynamics calculations reveal significant atom exchange in the (4)He(2) (+)+(3)He ionic reaction. Reaction probabilities are largely independent of vibrational state but sensitive to rotational excitation, suggesting experimental accessibility.
Area of Science:
- Quantum dynamics
- Chemical physics
- Atomic and molecular collisions
Background:
- Investigating isotopic replacement reactions is crucial for understanding reaction mechanisms.
- Helium isotopes offer a unique system for studying fundamental quantum effects in reactions.
Purpose of the Study:
- To perform full quantum dynamics calculations for the (4)He(2) (+)+(3)He ionic reaction.
- To determine state-to-state reactive probabilities and analyze reaction dynamics.
Main Methods:
- Utilized accurate ab initio potential-energy surface for quantum dynamics.
- Employed both time-dependent and time-independent quantum mechanical approaches.
- Applied the l-shifting approximation to estimate total reaction rates.
Main Results:
- High probabilities (up to 60%) for atom exchange (isotopic replacement) at zero total angular momentum.
- Reaction probabilities showed weak dependence on initial vibrational states.
- Reaction probabilities exhibited slight sensitivity to rotational excitation.
Conclusions:
- The (4)He(2) (+)+(3)He reaction exhibits significant isotopic replacement, driven by quantum dynamics.
- Calculated reaction rates are substantial, indicating potential for experimental observation and verification.
Related Concept Videos
01:28Isotopes and Radioisotopes
In the early 1900s, English chemist Frederick Soddy realized that an element could have atoms with different masses that were chemically indistinguishable. These different types are called isotopes — atoms of the same element that differ in mass. Isotopes differ in mass because they have different numbers of neutrons but are chemically identical because they have the same number of protons. Soddy was awarded the Nobel Prize in Chemistry in 1921 for this discovery.
An isotope containing more...
An isotope containing more...
02:48Ionic Bonding and Electron Transfer
Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell. Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by ionic bonds: electrostatic forces of attraction between oppositely charged cations and anions.
01:03¹H NMR Chemical Shift Equivalence: Homotopic and Heterotopic Protons
Protons in identical electronic environments within a molecule are chemically equivalent and have the same chemical shift. The replacement test is a useful tool to identify chemical equivalence and predict NMR spectra. A substituent replaces each of the protons being examined and the resulting molecules are compared. If the same molecule is obtained, the protons are equivalent or homotopic. Replacement of any hydrogens in ethane by chlorine yields chloroethane because all six protons are...
01:17Ion Exchange
Ion exchange chromatography separates charged molecules from a solution by reversibly exchanging them with mobile, or 'active', ions associated with the oppositely charged stationary phase. This method can be used to separate ions, soften and deionize water, and purify solutions. The polymers comprising the ion-exchange column are high-molecular-weight and chemically stable polymers, crosslinked to be porous and essentially insoluble. They are also functionalized with either acidic or basic...
03:18Radioactivity and Nuclear Equations
Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for hydrogen, neutrons. The number of protons in the nucleus is called the atomic number (Z) of the element, and the sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are isotopes of the same element.
A nuclide of an element has a specific number of protons and...
A nuclide of an element has a specific number of protons and...
02:31Elements: Chemical Symbols and Isotopes
A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is used to indicate one atom of mercury (microscopic domain) or to label a container of many atoms of the element mercury (macroscopic domain).
Some symbols are derived from the common English name of the element; others are abbreviations of the name in another language — Latin, Greek or German. For example, the symbol for aluminum (common name)...
Some symbols are derived from the common English name of the element; others are abbreviations of the name in another language — Latin, Greek or German. For example, the symbol for aluminum (common name)...