Saddle point electron emission

B. Historical Background of Saddle-Point Electron Emission... 

Calculations using the CDW-EIS model [38] are shown to be in good accord with 40-keV protons incident on molecular hydrogen and helium, and at this energy both theory and experiment show no evidence of any saddle-point enhancement in the doubly differential cross sections. However, for collisions involving 100-keV protons incident on molecular hydrogen and helium the CDW-EIS calculations [39] predict the existence of the saddle-point mechanism, but this is not confirmed by experiment. Recent CDW-EIS calculations and measurement for 80-keV protons on Ne by McSherry et al. [41] find no evidence of the saddle-point electron emission for this collision. 

Fig. 4.2. Complex saddle points t s (left panel), ts (middle panel), and kxs (s = i,j) (right panel) for the pair of solutions having the shortest travel times as discussed in the text. The figure is for ATI, for a Keldysh parameter of 7 = 0.975, and emission parallel to the laser held. The panels present the paths in the complex plane that are followed by the saddle points as a function of the final energy of the electron at the detector, which is indicated by the numbers (in multiples of Up). The figure shows how the saddle points of a pair approach each other very closely near the classical cutoff at 10 Up, which is the classical cutoff of the ATI energy spectrum. The contribution of the orbit that is drawn dashed has to be dropped after the cutoff. From [30]...

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