This book's coverage builds from basic underlying theory to more complex ideas related to
attosecond optics. It shows how the generation of attosecond optical pulses requires …

Recent experimental work using photons to study double excitation, double escape and
related processes near their respective thresholds is reviewed. These processes are of …

The helium atom, with one nucleus and two electrons, is a prototypical system to study
quantum many-body dynamics. Doubly excited states, or quantum states in which both …

We have observed photoexcitation of the dipole-forbidden 1 s 2 S 0 1→ 2 p 2 D 2 1
resonance in helium by measuring the nondipolar forward-backward asymmetry of …

We have investigated the nonlinear response of helium to intense extreme-ultraviolet
radiation from the free-electron laser in Hamburg (FLASH). We observe a spectral feature …

We have observed, for the first time, LS-forbidden triplet doubly excited states, in single
photon excitation of ground state helium, below the second ionization threshold. These …

We have made an investigation on the 2 s 2 p P o 1, 3 resonance states of helium
embedded in dense plasma environments. A screened Coulomb potential obtained from the …

Seeded free electron lasers theoretically have the intensity, tunability, and resolution
required for multiphoton spectroscopy of atomic and molecular species. Using the seeded …

The momentum transfer dependence of fundamental double excitation processes of helium
is studied by absolute measurements using an angular resolved fast-electron energy loss …

We have made an investigation on the doubly excited 1 P o resonance states of helium atom
in quantum plasmas using correlated exponential wave functions within the framework of the …