Abstract
ABSTRACT The new XUV sources, which deliver sp atially coherent pulses of high pea k power, allow to study elementaryprocesses in the light/solid interaction in the high intensity regime ( 10 11 W/cm 2 ). Here, we report twostudies which have used high-order laser harmonics (HH) generated in gas as the excitation source. Firstly, wehave investigated the dynamics of electron relaxation in the wide gap CdWO 4 dielectric crystal, an ecientscintillator material, using time-resolved luminescen ce spectroscopy. The kinetics decay of luminescence showsevidence of non radiative relaxation of the self-trapped excitons at the µs damage to surfaces of poly(methylmethacrylate) - PMMA, induced by a multi-shot XUV-irradiation (1 kHz reprate) for given uence, belowdamage threshold range of mJ/cm 2 . The main processes participating in the surface modication, polymerchain scission followed by the blow up of the volatile, molecular fragments and cross-linking in the near-surfacelayer of remaining material, are tentatively identied and associated to, crater formation for short-time exposure(< 1 min ) and surface hardening for long-time exposure ( 1 min ).Keywords: High order harmonics, electron relaxation dynamic, scintillator materials, XUV damage mecha-nisms, polymers
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