TY - GEN
T1 - Desorption mechanisms in PMMA irradiated by High order Harmonics
AU - De Grazia, M.
AU - Merdji, H.
AU - Auguste, T.
AU - Carré, B.
AU - Gaudin, J.
AU - Geoffroy, G.
AU - Guizard, S.
AU - Krejci, F.
AU - Kuba, J.
AU - Chalupsky, J.
AU - Cihelka, J.
AU - Hajkova, V.
AU - Ledinský, M.
AU - Juha, L.
PY - 2011/7/25
Y1 - 2011/7/25
N2 - The recent development of intense sources in the XUV range (10-100 nm), such as X-ray laser, Free Electron Laser and High order Harmonics (HoH), allows the study of high flux processes and ultra-fast dynamics in various domains. At the SLIC facility of CEA-Saclay, we have built a gas-harmonic beamline to investigate the interaction of intense XUV pulse with solids. High Harmonics of an IR laser (Ti:Sa at 800 nm, 35 fs, 13 mJ/pulse, 1 kHz) are generated in a rare gas cell (Xe). The useful XUV range (40-60 nm) is selected with metallic filters. The harmonic beam is focused with a parabolic mirror to a 10 μm focal spot on sample, leading to a fluence per shot of up to 1 mJ/cm2 (within a typical 10 fs pulse duration). Studies aimed at understanding the damaging mechanisms caused by XUV irradiation on surface of various samples by systematically varying of fluence and exposure time. For PMMA irradiated in the desorption regime (fluence/shot ≤ 0.2 mJ/cm2), the surface presents craters whose profile depends on the dose (Grey [Gy] = 1 J/kg). The crater evolution proceeds from the competition between two main degradation processes, that is chain scission and cross linking. Namely, at low dose (≤ 1 GGy) polymer chain scission is followed by the blow up of the volatile, molecular fragments, forming the crater. At high dose (> 10 GGy) the broken chain-ends, in the near-surface layer of the remaining material, recombine by cross-linking, opposing desorption by surface hardening. In a recent experiment at LCLS FEL facility, PMMA was irradiated at high fluence; the cross-linking signature was identified from Raman spectroscopy. A kinetic model could be adapted for interpreting these original and very promising results.
AB - The recent development of intense sources in the XUV range (10-100 nm), such as X-ray laser, Free Electron Laser and High order Harmonics (HoH), allows the study of high flux processes and ultra-fast dynamics in various domains. At the SLIC facility of CEA-Saclay, we have built a gas-harmonic beamline to investigate the interaction of intense XUV pulse with solids. High Harmonics of an IR laser (Ti:Sa at 800 nm, 35 fs, 13 mJ/pulse, 1 kHz) are generated in a rare gas cell (Xe). The useful XUV range (40-60 nm) is selected with metallic filters. The harmonic beam is focused with a parabolic mirror to a 10 μm focal spot on sample, leading to a fluence per shot of up to 1 mJ/cm2 (within a typical 10 fs pulse duration). Studies aimed at understanding the damaging mechanisms caused by XUV irradiation on surface of various samples by systematically varying of fluence and exposure time. For PMMA irradiated in the desorption regime (fluence/shot ≤ 0.2 mJ/cm2), the surface presents craters whose profile depends on the dose (Grey [Gy] = 1 J/kg). The crater evolution proceeds from the competition between two main degradation processes, that is chain scission and cross linking. Namely, at low dose (≤ 1 GGy) polymer chain scission is followed by the blow up of the volatile, molecular fragments, forming the crater. At high dose (> 10 GGy) the broken chain-ends, in the near-surface layer of the remaining material, recombine by cross-linking, opposing desorption by surface hardening. In a recent experiment at LCLS FEL facility, PMMA was irradiated at high fluence; the cross-linking signature was identified from Raman spectroscopy. A kinetic model could be adapted for interpreting these original and very promising results.
KW - Chain scission
KW - Cross-linking
KW - Desorption
KW - High order harmonics
KW - PMMA
KW - XUV pulses
U2 - 10.1117/12.890093
DO - 10.1117/12.890093
M3 - Conference contribution
AN - SCOPUS:79960538512
SN - 9780819486677
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Damage to VUV, EUV, and X-Ray Optics III
T2 - Damage to VUV, EUV, and X-Ray Optics III
Y2 - 18 April 2011 through 20 April 2011
ER -