[en] High-order harmonic pulse durations are measured using a laser and vacuum ultraviolet cross-correlation technique and the results are compared to theory. Harmonic pulses generated using moderate laser intensity are well described by current models and demonstrate that harmonic pulses are temporally broadened when produced at laser intensities sufficiently high to ionize the medium. At even higher generating laser intensity, measured pulse durations are longer than simulated pulse durations. We consider dipole emission from ions and distortion of the spatial laser profile as possible causes for the discrepancy

[en] A short-pulse, terawatt laser was used to generate and characterize plasmas appropriate for recombination pumped x-ray lasers. Thomson scattering was used to determine the electron and ion temperatures on a sub-picosecond time-scale. A recombination-pumped x-ray laser on the Ly-α transition of H-like Li was studied

[en] A beamline optimized for the bunch slicing technique has been construction at the Advanced Light Source (ALS). This beamline includes an in-vacuum undulator, soft and hard x-ray beamlines and a femtosecond laser system. The soft x-ray beamline may operate in spectrometer mode, where an entire absorption spectrum is accumulated at one time, or in monochromator mode. The femtosecond laser system has a high repetition rate of 20 kHz to improve the average slicing flux. The performance of the soft x-ray branch of the ALS slicing undulator beamline will be presented

[en] We have measured the absorption of x-rays in neon gas in the presence of a strong laser pulse. The femtosecond x-rays were tuned to energies near the neon 1s-3p resonance, and the laser intensity of 10¹³ W/cm² was below the intensity required to alone ionize neon. We observed strong modification of the x-ray absorption when the neon was subjected to laser light that was temporally overlapped with the x-rays.

[en] This postdeadline paper was presented at the Conference on Lasers and Electro-Optics (CLEO), May 23-28, 1999, Baltimore, Maryland.(c) 1999 Optical Society of America

[en] The first use of pseudo-single-bunch pulse picking in time-resolved experiments at the Advanced Light Source is reported. The pseudo-single-bunch technique improves signal to noise and drastically reduces dose-induced sample damage. Laser pump–X-ray probe experiments require control over the X-ray pulse pattern and timing. Here, the first use of pseudo-single-bunch mode at the Advanced Light Source in picosecond time-resolved X-ray absorption experiments on solutions and solids is reported. In this mode the X-ray repetition rate is fully adjustable from single shot to 500 kHz, allowing it to be matched to typical laser excitation pulse rates. Suppressing undesired X-ray pulses considerably reduces detector noise and improves signal to noise in time-resolved experiments. In addition, dose-induced sample damage is considerably reduced, easing experimental setup and allowing the investigation of less robust samples. Single-shot X-ray exposures of a streak camera detector using a conventional non-gated charge-coupled device (CCD) camera are also demonstrated