Back to Search
Start Over
Observation of a highly conductive warm dense state of water with ultrafast pump–probe free-electron-laser measurements
- Source :
- Matter and Radiation at Extremes, Vol 6, Iss 5, Pp 054401-054401-12 (2021), Matter and radiation at extremes 6(5), 054401 (2021). doi:10.1063/5.0043726
- Publication Year :
- 2021
- Publisher :
- AIP Publishing LLC, 2021.
-
Abstract
- The electrical conductivity of water under extreme temperatures and densities plays a central role in modeling planetary magnetic fields. Experimental data are vital to test theories of high-energy-density water and assess the possible development and presence of extraterrestrial life. These states are also important in biology and chemistry studies when specimens in water are confined and excited using ultrafast optical or free-electron lasers (FELs). Here we utilize femtosecond optical lasers to measure the transient reflection and transmission of ultrathin water sheet samples uniformly heated by a 13.6 nm FEL approaching a highly conducting state at electron temperatures exceeding 20 000 K. The experiment probes the trajectory of water through the high-energy-density phase space and provides insights into changes in the index of refraction, charge carrier densities, and AC electrical conductivity at optical frequencies. At excitation energy densities exceeding 10 MJ/kg, the index of refraction falls to n = 0.7, and the thermally excited free-carrier density reaches n$_e$ = 5 × 10$^{27}$ m$^{−3}$, which is over an order of magnitude higher than that of the electron carriers produced by direct photoionization. Significant specular reflection is observed owing to critical electron density shielding of electromagnetic waves. The measured optical conductivity reaches 2 × 10$^4$ S/m, a value that is one to two orders of magnitude lower than those of simple metals in a liquid state. At electron temperatures below 15 000 K, the experimental results agree well with the theoretical calculations using density-functional theory/molecular-dynamics simulations. With increasing temperature, the electron density increases and the system approaches a Fermi distribution. In this regime, the conductivities agree better with predictions from the Ziman theory of liquid metals.
- Subjects :
- Nuclear and High Energy Physics
Electron density
02 engineering and technology
Electron
Photoionization
QC770-798
021001 nanoscience & nanotechnology
01 natural sciences
Optical conductivity
Atomic and Molecular Physics, and Optics
Nuclear Energy and Engineering
13. Climate action
Electrical resistivity and conductivity
Excited state
Nuclear and particle physics. Atomic energy. Radioactivity
0103 physical sciences
Charge carrier
ddc:530
Electrical and Electronic Engineering
Atomic physics
010306 general physics
0210 nano-technology
Refractive index
Subjects
Details
- Language :
- English
- Volume :
- 6
- Issue :
- 5
- Database :
- OpenAIRE
- Journal :
- Matter and Radiation at Extremes
- Accession number :
- edsair.doi.dedup.....0fd9f72a420b9c189d5aa1a6c79a2ee5