Radiative Electron Capture to the Continuum and the Short-Wavelength Limit of Electron-Nucleus Bremsstrahlung in 90A MeV U{sup 88+}(1s{sup 2}2s{sup 2})+N{sub 2} Collisions

We have measured the continuum momentum distribution for radiative electron capture to the continuum (RECC) cusp electrons in 90A MeV U{sup 88+}+N{sub 2}{yields}U{sup 88+}+(N{sub 2}{sup +}*)+e{sub cusp}(0 deg.)+h{nu} (RECC) collisions. We demonstrate that x rays coincident with RECC cusp electrons originate from the short-wavelength limit of the electron-nucleus bremsstrahlung and explain the asymmetric cusp shape by comparison with theory within the relativistic impulse approximation.