© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

Mediterranean Journal of Chemistry

Angular Momentum Transfer at the Chemo-ionization and Spin Exchange Processes. Interaction between Spin Polarized Metastable Helium Atoms

Victor A. Kartoshkin

Published Oct 7, 2022• 0 citations

Abstract

In the collision of spin-polarized atoms, the transmission of electron polarization between colliding particles is possible. A similar situation occurs in a collision, for example, between alkali atoms in the ground state. If one of the colliding particles is in an excited state and its energy is sufficient for ionization of the collision partner, then along with the elastic process (spin exchange), an inelastic process (ionization) is also possible, as a result of these processes polarization can also be transferred to the partner. Simultaneously occurring elastic and inelastic processes at the collision between two helium atoms are possible if these atoms are in the metastable (23S1) state. The paper discusses the interaction between spin-polarized metastable atoms of helium-3 and helium-4 isotopes under conditions of optical pumping of atoms. Complex interaction potentials of the atoms under consideration were constructed and on their basis, the spin exchange and chemo-ionization cross-sections were calculated. Using these cross-sections, expressions for the transfer of orientation and alignment from one atom to another were obtained.

DOI: 10.13171/mjc02210071641kartoshkin

Related papers

Interaction between spin polarized alkali atoms

Victor A. Kartoshkin

Collisions of alkali-metal atoms in the ground state with the electron spin S = 1/2 are accompanied by exchange of electron coordinates between colliding particles, which leads to polarization transfer between them (i.e., to the well-known phenomenon of spin exchange). In addition, along with the polarization transfer from one partner to another, the magnetic resonance lines of colliding atoms are broadened and shifted in spin-exchange collisions. In particular the last two processes depend on the complex spin-exchange cross section. The real part of the cross section determines the so-called "spin-exchange cross section," which is responsible for the broadening of magnetic resonance lines, while the imaginary part determines the shift cross section, which governs the frequency shift of magnetic resonance. In order to describe the spin-exchange process one have to know complex spin-exchange cross sections. Complex spin-exchange cross sections are calculated on the basis of the data on the singlet (X 1 Σ + ) and triplet (a 3 Σ + ) potentials describing the interaction alkali-metal atoms in the ground state. Collisions of alkali-metal atoms Cs, Rb, K, Na in the ground state are considered in the energy interval of 10 −4 −10 −2 au.

Journal of Physics Conference Series•Dec 1, 2018•0 citations

Spin exchange cross sections for collisions of metastable helium atoms with lithium atoms in the ground state

Victor A. Kartoshkin

The spin exchange and chemi-ionization cross sections for the metastable helium atom-lithium atom in the ground state system have been calculated. Using data on the interaction potentials obtained in this study, the spin exchange cross sections are determined for the first time for the He(23 S 1)-Li(22 S 1/2) system in the interval of collision energies from 5 × 10−3 to 16 eV.

Technical Physics Letters•Dec 1, 2007•0 citations

Spin polarization transfer in ground and metastable helium atom collisions

D. Vrinceanu, H. R. Sadeghpour

Cross sections and rate constants for total elastic, diffusion and transfer of metastability for collisions between He(11S)–He(23S) and He(11S)–He(23P) atoms over a wide range of energies and temperatures are presented. The rate constant for spin metastability excitation in He(11S)–He(23P) collision is several orders of magnitude larger than that for He(11S)–He(23S) collision at cold temperatures, due to attractive 3Πg potential interaction.

New Journal of Physics•Jun 28, 2010•7 citations

Chemi-ionization and spin exchange upon collisions of metastable helium atoms with potassium atoms in the ground state

Victor A. Kartoshkin, G. V. Klement’ev

The spin exchange and chemi-ionization cross sections have been calculated for the metastable helium atom-potassium atom system in the ground state. The data on the spin exchange cross section in the system He(23 S 1)-K(42 S 1/2) have been obtained for the first time. The cross sections were calculated for the collision energies ranging from 2 × 10−4 to 60 × 10−4 au The chemi-ionization cross sections obtained have been compared with the data in the literature.

Optics and Spectroscopy•Apr 1, 2007•1 citation

Collisions of Lithium Atoms in Ground State. Complex Spin-Exchange Cross Sections

Victor A. Kartoshkin

Abstract Interaction of two polarized lithium atoms (7Li) is analyzed. When such atoms collide with each other, spin exchange, i.e., an exchange of electron polarization between colliding atoms, takes place in addition to elastic scattering. Simultaneously with polarization transfer, spin exchange leads to frequency shift of the magnetic resonance of colliding atoms. Based on the data on potentials describing interaction between two lithium atoms, energy dependences of spin-exchange cross section and cross section of frequency shift of magnetic resonance are calculated for the first time.

Optics and Spectroscopy•Jun 1, 2021•3 citations

Atom-atom and atom-ion collisions. III. Collisions involving excitation transfer, spin exchange or depolarization, without internal energy change

H. S. W. Massey

Three further types of collision between atomic systems in which no change of internal energy takes place are considered. These are collisions in which transfer of excitation occurs between two similar atoms, spin exchange collisions, and collisions in which the direction but not the magnitude of the orbital angular momentum of an excited atom is changed on impact. An account is given of the theory of these processes in relation to that for other processes, elastic scattering and symmetrical charge exchange, discussed in the earlier articles, in which no change of internal energy occurs. Methods for measuring the relevant cross sections are described. These make use of optical pumping and nuclear magnetic resonance techniques. Comparison is made between observed and calculated cross sections.

Contemporary Physics•Jul 1, 1972•5 citations

In the collision of spin-polarized atoms, the transmission of electron polarization between colliding particles is possible. A similar situation occurs in a collision, for example, between alkali atoms in the ground state. If one of the colliding particles is in an excited state and its energy is sufficient for ionization of the collision partner, then along with the elastic process (spin exchange), an inelastic process (ionization) is also possible, as a result of these processes polarization can also be transferred to the partner. Simultaneously occurring elastic and inelastic processes at the collision between two helium atoms are possible if these atoms are in the metastable (23S1) state. The paper discusses the interaction between spin-polarized metastable atoms of helium-3 and helium-4 isotopes under conditions of optical pumping of atoms. Complex interaction potentials of the atoms under consideration were constructed and on their basis, the spin exchange and chemo-ionization cross-sections were calculated. Using these cross-sections, expressions for the transfer of orientation and alignment from one atom to another were obtained.

Collisions of alkali-metal atoms in the ground state with the electron spin S = 1/2 are accompanied by exchange of electron coordinates between colliding particles, which leads to polarization transfer between them (i.e., to the well-known phenomenon of spin exchange). In addition, along with the polarization transfer from one partner to another, the magnetic resonance lines of colliding atoms are broadened and shifted in spin-exchange collisions. In particular the last two processes depend on the complex spin-exchange cross section. The real part of the cross section determines the so-called "spin-exchange cross section," which is responsible for the broadening of magnetic resonance lines, while the imaginary part determines the shift cross section, which governs the frequency shift of magnetic resonance. In order to describe the spin-exchange process one have to know complex spin-exchange cross sections. Complex spin-exchange cross sections are calculated on the basis of the data on the singlet (X 1 Σ + ) and triplet (a 3 Σ + ) potentials describing the interaction alkali-metal atoms in the ground state. Collisions of alkali-metal atoms Cs, Rb, K, Na in the ground state are considered in the energy interval of 10 −4 −10 −2 au.

Abstract Interaction of two polarized lithium atoms (7Li) is analyzed. When such atoms collide with each other, spin exchange, i.e., an exchange of electron polarization between colliding atoms, takes place in addition to elastic scattering. Simultaneously with polarization transfer, spin exchange leads to frequency shift of the magnetic resonance of colliding atoms. Based on the data on potentials describing interaction between two lithium atoms, energy dependences of spin-exchange cross section and cross section of frequency shift of magnetic resonance are calculated for the first time.

Three further types of collision between atomic systems in which no change of internal energy takes place are considered. These are collisions in which transfer of excitation occurs between two similar atoms, spin exchange collisions, and collisions in which the direction but not the magnitude of the orbital angular momentum of an excited atom is changed on impact. An account is given of the theory of these processes in relation to that for other processes, elastic scattering and symmetrical charge exchange, discussed in the earlier articles, in which no change of internal energy occurs. Methods for measuring the relevant cross sections are described. These make use of optical pumping and nuclear magnetic resonance techniques. Comparison is made between observed and calculated cross sections.