Photoionization Delay in He, Ne, Ar and Kr

We study photoionization of various noble gas atoms by attosecond pulses produced in High Harmonic Generation (HHG). We use a pump-probe experiment to measure the time delays of electrons photoionized from Neon, Argon, and Krypton relative to those photoionized from Helium atoms. The Attosecond Pulse Train (APT) is characterized and the relative delay in photoionization of various noble gases is measured. The photoionization delay of Ne, Ar, and Kr is determined using previously calculated values for the He atomic delay and the delay associated with the probe process.