Cover Image

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

Victor Kartoshkin

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.


Full Text:

PDF

References


- Zhitnikov R.A., Kartoshkin V.A. et al., Metastability exchange in a mixture of He3 and He4 isotopes,

Sov.Phys. JETP, 1976, 44, 924-930.

- Vrinceanu D. and Sadeghpour H.R., Spin polarization transfer in ground and metastable

helium atom collisions, New Journal of Physics, 2010, 12, 065039.

- Stas R. J. W., McNamara J. M., Hogervorst W., and Vassen W., Homonuclear ionizing collisions of laser-cooled metastable helium atoms, Phys. Rev. A, 2006, 73, 032713.

- McNamara J. M., Stas R. J. W., W. Hogervorst, and W. Vassen arXiv:physics/0701194

https://doi.org/10.48550/arXiv.physics/0701194

- Kartoshkin V.A., Chemoionization and spin exchange in collisions of excited metastable helium atoms with sodium atoms in the ground state: II. The calculation of cross sections for chemo-ionization and spin exchange, Optics and Spectroscopy, 1998, 85, 177-180.

- Leo P.J., Venturi V., Whittingham I.B., J. F. Babb, Ultracold collisions of metastable helium atoms, Phys. Rev. A, 2001, 64, 042710-1 - 042710-8.

- Mott N.F. and Massey H.S.W., The Theory of Atomic Collisions; 3rd ed., Oxford: Clarendon Press, 1965, p.858.

- Wigner E. Ueber die Erhaltungssatze in der Quantenmechanik, 1927, Gotting.Nachr. 1927, 4, 375-381.

- Dalgarno A., Rudge M. J., Spin-Change Cross-Sections for Collisions between Alkali Atoms, Proc. Roy. Soc. (London), 1965, A286, 519-524

- Melnikov V.D., Kartoshkin V.A., Klementiev G.V., Spin exchange, accompanying with nonelastic process under the collision of two atomic particles with S1=S2=1 electron spins, Zhurnal Tekhnicheskoi Fiziki , 1988, 58, 830-833 (in Russian).

- Miiller M.W., Merz A., Ruf M.-W., Hotop H., Meyer W., and Movre M., Experimental and theoretical studies of the Bi-excited collision systems He*(23S) + He*(23S, 21S) at thermal and subthermal kinetic energies Z. Phys. D, 1991, 21, 89-112.

- Kartoshkin V.A., Chemiionization and spin exchange in collisions of triplet metastable atoms in a mixture ofhelium isotopes, Optics and Spectroscopy, 2008, 105, 657-662.




DOI: http://dx.doi.org/10.13171/mjc02210071641kartoshkin

Copyright (c) 2022 Mediterranean Journal of Chemistry