Optical properties of compressed fluid hydrogen in the region where dissociation and metallization is observed are computed by ab initio methods and compared with recent experimen- tal results. We confirm that at T>3,000 K, both processes are continuous, while at T<1,500 K, the first-order phase transi- tion is accompanied by a discontinuity of the dc conductivity and the thermal conductivity, while both the reflectivity and absorption coefficient vary rapidly but continuously. Our results support the recent analysis of National Ignition Facility (NIF) experiments [Celliers PM, et al. (2018) Science 361:677–682], which assigned the inception of metallization to pressures where the reflectivity is ⇠0.3. Our results also support the conclusion that the temperature plateau seen in laser-heated diamond-anvil cell (DAC) experiments at temperatures higher than 1,500 K corre- sponds to the onset of optical absorption, not to the phase transition. hydrogen
Optical properties of high-pressure fluid hydrogen across molecular dissociation
Carlo Pierleoni
2019-01-01
Abstract
Optical properties of compressed fluid hydrogen in the region where dissociation and metallization is observed are computed by ab initio methods and compared with recent experimen- tal results. We confirm that at T>3,000 K, both processes are continuous, while at T<1,500 K, the first-order phase transi- tion is accompanied by a discontinuity of the dc conductivity and the thermal conductivity, while both the reflectivity and absorption coefficient vary rapidly but continuously. Our results support the recent analysis of National Ignition Facility (NIF) experiments [Celliers PM, et al. (2018) Science 361:677–682], which assigned the inception of metallization to pressures where the reflectivity is ⇠0.3. Our results also support the conclusion that the temperature plateau seen in laser-heated diamond-anvil cell (DAC) experiments at temperatures higher than 1,500 K corre- sponds to the onset of optical absorption, not to the phase transition. hydrogenFile | Dimensione | Formato | |
---|---|---|---|
Rillo et al._2019_Optical properties of high-pressure fluid hydrogen across molecular dissociation_Proceedings of the National Academy o.pdf
accesso aperto
Descrizione: articolo pdf reprint
Tipologia:
Documento in Post-print
Licenza:
Creative commons
Dimensione
1.66 MB
Formato
Adobe PDF
|
1.66 MB | Adobe PDF | Visualizza/Apri |
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.