Coherence Measurement of Tensor Multipoles of Asymmetrically Excited Atomic States

A specific coherence measurement technique is described, which yields the relative magnitudes of all predicted orientation and alignment parameters in tilted-foil-excited levels of ions and atoms. Quantum-beat frequencies and relative magnitudes are measured as a function of applied magnetic field strength and direction, and analyzed using Fano-Macek theory. The multipole moments of tilted-foil-excited 40-keV ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ $4d{}_{}{}^1{}_{}{}^{}D_2^{}{}_{}{}^{}$ atoms are measured and related to proposed excitation mechanisms.