XXVI International Conference on Photonic, Electronic and Atomic Collisions IOP Publishing Journal of Physics: Conference Series 194 (2009) 102010 doi:10.1088/1742-6596/194/10/102010
A Young double-slit experiment using a single electron source : Oscillations in the angular distribution of Auger-line width ,1
†,2
†,2
,1
F. Frémont* , R. O. Barrachina , S. Suarez and J.-Y. Chesnel*
* Université de Caen-CEA-CNRS-EnsiCaen-CIMAP, 6 bd du Mal Juin, F-14050 Caen Cedex France † Centro Atómico Bariloche and Instituto Balseiro 8400 S. C. de Bariloche, Río Negro, Argentina Synopsis We present evidence for two-center interference effects in the autoionization of a Helium atom following a 2+
double capture process in a He + H2 collision, by looking, not at the total intensity as in a previous article [1], but at the full width at half maximum of the energy distribution at a function of the observation angle.
In a recent article [1], we reported on a novel Young-type experiment, where one single electron interferes with itself after traversing a double-center system. We studied the process He 2+ + H 2 (1σ 2 ) → He** (2lnl' , n ≥ 2 ) + H + + H + (1) → He + + H + + H + + e −
– 160°. Within the uncertainties, that are smaller than 0.02 eV, at least four well defined oscillations are visible, superimposed on the main dependency. These oscillations represent a clear demonstration of the presence of an atomic-scale Young-type interference of the emitted electron with the two+ center 2H dimer. Thus, the present results complete and reinforce the analysis performed previously on the undiscerned 2lnl' (n ≥ 2) configurations.
where the outgoing helium atom plays the role of the source of a single-electron emitted with a well-defined wavelength λ, of the order of ~0.3 nm, while the two residual protons provide the double-center interferometer. In our previous article [1] we reported the observation of very well defined oscillations in the angular distribution of the total intensity, in complete agreement with the theoretical model [2]. In this communication, we present further evidence of two-center interference effects in process (1) by looking, not at the total intensity, but at the autoionization cross section doubly differential in the detection angle and the electron energy. More specifically, we investigate the full width at half maximum (FWHM) of the energy distribution as a function of the detection angle. Since high resolution spectra were obtained in our experiment, we focus on the Auger 2 1 deexcitation of the 2s S configuration. The experimental widths are determined after fitting the spectra with Gaussian curves, at observation angles ranging from 120° up to 160°. In addition, the angular width distribution is compared with the results obtained using the theory developed previously [2]. The FWHMs are presented in Figure 1 (full circles), as a function of the detection angle in the range 120° 1 2
2+
1,6
Experimental width (eV)
1,5
1,4
1,3
1,2
1,1
1,0
0,9 120
130 140 150 Observation angle (deg.)
160
2 1
Fig. 1. Measured and calculated FWHM for the 2s S 2+ configuration in He + H2 collisions, as a function of the detection angle.
References [1] J.-Y. Chesnel, A. Hajaji, R. O. Barrachina and F. Frémont, 2007 Phys. Rev. Lett. 98, 100403. [2] R. O. Barrachina and M. Zitnik, J. Phys. B 37, 3847 (2004).
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30 keV He + H2
1,7
1
