Frequency doubling of interference structures in electron emission interferences from H_{2} by 68-MeV/u Kr^{33+} impact

Interference structures associated with the emission of electrons from H-2 by fast Kr33+ ions (v/c=0.3) are found to exhibit oscillations of second order superimposed on the main oscillatory structure. The secondary oscillations occur with about twice the frequency of the main oscillations. While the primary structure is produced by the coherent emission of electrons from the two atomic centers, similar to Young's two-slit experiment, our theoretical analysis indicates that the frequency doubling is a second-order effect, where the electron wave emitted at one center interferes with the wave backscattered at the other center.