Preliminary analysis to achieve a high-precision measurement of the excitation energy of the He (2p 3d) 1P doubly excited state in helium using landmark states in neon

Full text: We present the groundwork a scheme to employ both first-and third- harmonic undulator light to excite states of well-known energy in singly-excited neon and high excitation energy doubly-excited states in helium in a single scan. This simultaneous excitation superimposes the features of the two spectra, providing landmarks for accurate measurement of the helium features. We measured an excitation energy of 64.1198(14) for the He (2p 3d) 1P which differs by 5.3 meV from the value calculated initnik et al. These measurements were performed at a resolving power more than 4 times the designed operating range of the BL 6.2 R gas-phase beamline at Elettra, where the data were recorded. This induced significant technical challenges in calibrating the energy scale. Copyright (2005) Australian Institute of Physics