Laser pump and X-ray probe core-level photoemission experiments probe surface photovoltage transients on p-type Si(111) surfaces. The data are consistent with a picture where the dynamics of mobile surface charge dominate the photovoltage shift, with changes in the surface-states charge density of only secondary importance. A value for the equilibrium band bending is determined, which suggests that a residual oxide layer reduces the density of surface states.

We report, to our knowledge, the first use of pump-probe photoemission spectroscopy to study core-level dynamics during a laser-driven phase transition. Synchrotron x-rays probe the kinetics of cluster formation during the initial moments of femtosecond laser ablation.

Author(s): Glover, T.E.; Ackermann, G.D.; Belkacem, A.; Feinberg, B.; Heimann, P.A.; Hussain, Z.; Padmore, H.A.; Ray, C.; Schoenlein, R.W.; Steele, W.F.

We report, to our knowledge, the first use of pump-probe photoelectron spectroscopy to study core-level dynamics during a laser-driven phase transition. Synchrotron xrays probe the phase transition dynamics during the initial moments of femtosecond laser ablation.

We report results on experiments using combined laser and synchrotron radiation. Picosecond laser pulses at 800nm are used to induce surface photovoltage transients in p-type Si samples. A two-component decay is observed. The fast component of decay provides a direct measure of synchrotron soft X-ray pulse durations.

This paper presents preliminary data on analyses of selected materials using two state-ofthe- art XPS systems: the Physical Electronics Inc. (PHI, Eden Prairie, MN) Quantum 2000 instrument and the microXPS beamline (7.3.2.1) at the Advanced Light Source (ALS). This research compares and contrasts relevant performance characteristics of the two systems including elemental and chemical state detection sensitivity, imaging capabilities including lateral resolution and useful image fields, role of X-ray dose damage to surface, analysis speed as well as analytical throughput.