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{{Infobox scientist
| name = Reiner Feltgen
| alt = Reiner Feltgen
| residence = D-37688 Beverungen, Germany
| nationality = German
| fields = Atomic and molecular physics
| work_institution = Max-Planck-Institut für Strömungsforschung, Göttingen
| known_for = Experimental determination of the He–He interatomic potential
}}

'''Reiner Feltgen''' is a German physicist known for his experimental work in atomic and molecular physics, particularly the study of interatomic potentials and chemi-ionization reactions using crossed atomic and molecular beams.

==Biography==
Feltgen carried out his research at the Max-Planck-Institut für Strömungsforschung (Max Planck Institute for Fluid Dynamics) in Göttingen, Germany, where he worked in the field of atomic and molecular beam physics. He resides in Beverungen, Germany.

==Work==
Feltgen's research centered on the measurement and interpretation of atomic and molecular collision processes at thermal and low collision energies. Using crossed-beam techniques, he investigated elastic scattering, interatomic interaction potentials, and chemi-ionization (Penning ionization) reactions.

A central contribution was the experimental determination of the helium–helium (He<sub>2</sub>) ground-state interaction potential. In a widely cited 1982 study with H. Kirst, K. A. Köhler, H. Pauly, and F. Torello, high-resolution total differential cross-section measurements were combined with a reliable potential model to obtain the He<sub>2</sub> ground-state potential from experiment. The weakly bound helium dimer has since been of considerable interest in the study of quantum-mechanical few-body systems.

Feltgen also studied chemi-ionization reactions in which metastable helium atoms, He*(2<sup>1</sup>S) and He*(2<sup>3</sup>S), collide with rare-gas and other target atoms. This work included measurements of the energy dependence of ionization cross sections over a wide range of collision energies, contributing to the understanding of Penning and associative ionization processes.

==Selected publications==
Several&nbsp;articles in <em>Journal of Chemical Physics</em>, <em>Chemical Physics Letters</em>, <em>Physical Review A</em>, etc.

* R. Feltgen, H. Kirst, K. A. Köhler, H. Pauly and F. Torello, "Unique determination of the He<sub>2</sub> ground state potential from experiment by use of a reliable potential model," <em>Journal of Chemical Physics</em>, V76, N5, pp. 2360-2378 (1982).
* "The Chemi-Ionization of He*(2<sup>1,3</sup>S) + Ar,Kr,Xe for Collision Energies from 0.003 to 6 eV," <em>Journal of Chemical Physics</em>, V111, N16, pp. 7298-7315 (1999). (with five co-authors)

==External links==
* [https://pubs.aip.org/aip/jcp/article-abstract/76/5/2360/218909 Unique determination of the He2 ground state potential from experiment (J. Chem. Phys., 1982)]
* [https://pubs.aip.org/aip/jcp/article/111/16/7298/294962 The chemi-ionization of He*(2 1,3S) + Ar, Kr, Xe (J. Chem. Phys., 1999)]

[[Category:Scientist|Feltgen Reiner]]
[[Category:Worldwide List of Dissident Scientists]]