Optical problems abound in the pursuit of attosecond science, as measurements at such short timescales push the boundaries of both optics and fundamental quantum mechanics. The x-ray transitions accessed by attosecond pulses are responsive to charge, chemical oxidation state, and electronic environment and exhibit sensitive shifts even with vibrational excitation. An introduction to attosecond measurements is presented, with a goal to determine electron dynamical timescales. Investigations involve the development of methods to explore coherent electronic superpositions and timescales for ionization, and in the solid-state to determine how fast are band gap and phase changes.

Research supported by DOE, NSF, NSSEFF, DARPA, ARO, AFOSR, and the Keck Foundation.