Endothermal fine-structure transition of metastable argon atoms passing through a micro-slit copper grating

• Published in: Europhysics letters 2002-10, Vol.60 (2), p.207-213
• Main Authors: Karam, J. C, Boustimi, M, Baudon, J, Ducloy, M, Perales, F, Reinhardt, J, Bocvarski, V, Mainos, C, Levron, F, Robert, J
• Format: Article
• Language: English
• Subjects: 03.75.Be; 12.20.Fv; 34.50.Dy; Atomic and molecular collision processes and interactions; Atomic and molecular physics; Atomic properties and interactions with photons; Exact sciences and technology; Fine and hyperfine structure; Interactions of atoms, molecules and their ions with surfaces; photon and electron emission; neutralization of ions; Physics; Properties of atoms and atomic ions; Scattering of atoms, molecules and ions
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/epl/i2002-00340-1

The endothermal fine-structure transition ($^{3}P_{2} \rightarrow {}^3P_0$ —175 $\un{meV}$) of metastable argon atoms traversing at a velocity of 1030$\un{m/s}$ a micro-slit copper grating the normal axis of which is set, in a first configuration, at $60^\circ$ with respect to the incident beam axis, is observed. The related differential cross-section (DCS) is sharply peaked at $60^\circ$ and its velocity dependence reveals the expected threshold at 900$\un{m/s}$. In a second configuration, the grating is set at an angle of $43^\circ$, allowing for a 7% transmission of the incident beam. Atoms elastically scattered by the corner edges of the grating slits are observed in the angular range $1^\circ$–$4^\circ$ and the elastic DCS is measured in relative values. In spite of such a widely unsuited geometry, the endothermal process still appears (with a magnitude 10 times smaller than before), because of the surface corrugation. The inelastic DCS is now peaked at $57.5^\circ$ with a width of about $6^\circ$, as predicted from the corrugation angle distribution deduced from the inelastic DCS of metastable $\chem{N_2^*}$ molecules traversing the same grating.