Anticrossing spectrometry with synchrotron light
AbstractThe anticrossing structure of the 1s7l manifold of the helium atom in combined dc electric and magnetic fields is studied using a broadband photoexcitation with synchrotron light. The anticrossing signal is provided by the yield of atoms in the metastable 1s2s states to which the 1s7l states cascade. The mapping resolution depends solely on the homogeneity of the two fields in the target region, which is formed by the intersection of the synchrotron beam and the helium atom beam. The measured positions, as well as anticrossing intensities and widths, measured in the region of 1–1.5 kV/cm and 0–10 mT are in excellent agreement with the results of our extended theoretical simulations based on highly accurate zero-field wave functions. By centering the photoexcitation window to 65.110 and 65.130 eV, the same technique is applied to look for the anticrossings in the vicinity of the 7+1P1o–7d3D1o and 7d1P1o–8−1P1o pairs of doubly excited states, respectively.