Free Electron Laser Measurement of Liquid Carbon Reflectivity in the Extreme Ultraviolet
Abstract
Ultrafast time-resolved extreme ultraviolet (EUV) reflectivity measurements of optically pumped amorphous carbon (a-C) have been performed with the FERMI free electron laser (FEL). This work extends the energy range used in previous reflectivity studies and adds polarization dependence. The EUV probe is known to be sensitive to lattice dynamics, since in this range the reflectivity is essentially unaffected by the photo-excited surface plasma. The exploitation of both s- and p-polarized EUV radiation permits variation of the penetration depth of the probe; a significant increase in the characteristic time is observed upon increasing the probing depth (1 vs. 5 ps) due to hydrodynamic expansion and consequent destruction of the excited region, implying that there is only a short window during which the probed region is in the isochoric regime. A weak wavelength dependence of the reflectivity is found, consistent with previous measurements and implying a maximum electronic temperature of 0.8 eV ± 0.4.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 23, 2020
- Source ID
- 10.3390/photonics7020035
Entities
People
- Alberto Simoncig
- Alessandro Gessini
- Claudio Masciovecchio
- Craig Schwartz
- Emiliano Principi
- Filippo Bencivenga
- G. Kurdi
- Laura Foglia
- Riccardo Mincigrucci
- Richard J. Saykally
- Shane Devlin
- Sumana L. Raj
Organizations
- Lawrence Berkeley National Laboratory
- National Science Foundation
- United States Army Research Laboratory