High-order harmonic generation experiments with IR laser pulses

We report on the first experiments of high-order harmonic generation done with the 100 Hz high-energy optical parametric amplifier (OPA) of the Advanced Laser Light Source. Using krypton and argon as targets, we show that the OPA's signal beam - with a wavelength range from 1200 nm to 1600 nm, 1.3 mJ to 0.8 mJ of pulse energy and 100 fs pulse duration - can generate fully tunable XUV radiation down to a wavelength of 15 nm. We have also started to investigate the use of the OPA pulses for molecular imaging. Inducing molecular alignment with 800 nm, 70 fs pulses, we have measured the high harmonics spectra generated with 1300 nm pulses from nitrogen molecules oriented at various angles with respect to the ionizing field, in order to study for the first time the technique of molecular orbital tomography with a laser wavelength different than 800 nm.