Dynamical correlation in double excitations of helium studied by high-resolution and angular-resolved fast-electron energy-loss spectroscopy in absolute measurements

The momentum transfer dependence of fundamental double excitation processes of helium is studied by absolute measurements using an angular resolved fast-electron energy loss spectrometer with high energy resolution. It elucidates the dynamical correlations, in terms of internal correlation quantum numbers, K, T, and A. The Fano profile parameters q, f(a), rho2, f, and S of doubly excited states (2)(1,0)+2 (1)S(e), (2)(1,0)+2 (1)D(e), and (2)(0,1)+2 (1)P(o) are reported as functions of momentum transfer K2. Qualitative analysis is given for the states of (2)(-1,0)+2 (1)S(e) and (2)(1,0)+2 (1)S(e).