Impact of the electron-phonon coupling factor and electron heat capacity on the thermal response of targets irradiated by femtosecond laser

2018 ◽  
Vol 30 (4) ◽  
pp. 042004
Author(s):  
G. H. Al-Malkawi ◽  
A. Hassanein
Keyword(s):  
Heat Capacity ◽  
Femtosecond Laser ◽  
Thermal Response ◽  
Coupling Factor ◽  
Phonon Coupling ◽  
Electron Heat Capacity ◽  
Electron Heat ◽  
Electron Phonon Coupling

Influence of Inter- and Intraband Transitions to Electron Temperature Decay in Noble Metals After Short-Pulsed Laser Heating

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Patrick E. Hopkins
Keyword(s):  
Heat Capacity ◽  
Electron Temperature ◽  
Noble Metals ◽  
Coupling Factor ◽  
Phonon Coupling ◽  
Electron Heat Capacity ◽  
Temperature Decay ◽  
Electron Heat ◽  
Electron Phonon Coupling ◽  
Pulsed Laser Heating

This work examines the effects of photonically induced interband excitations from the d-band to states at the Fermi energy on the electron temperature decay in noble metals. The change in the electron population in the d-band and the conduction band causes a change in electron heat capacity and electron-phonon coupling factor. In noble metals, due to the large d-band to Fermi energy separation, the contributions to electron heat capacity and electron-phonon coupling factor of intra- and interband transitions can be separated. The two temperature model describing electron-phonon heat transfer after short-pulsed laser heating is solved using the expressions for heat capacity and electron-phonon coupling factor after intra- and interband excitations, and the predicted electron temperature change of the intra- and interband excited electrons are examined. A critical fluence value is defined that represents the absorbed fluence needed to fill all available states at a given photon energy above the Fermi level. At high absorbed laser fluences and pulse energies greater than the interband transition threshold, the interband and intraband contributions to thermophysical properties differ and are shown to affect temporal electron temperature profiles.

Electron–phonon coupling factor and electron heat capacity of 6H-SiC

2021 ◽  
pp. 1-8
Author(s):  
Wenlong Liao ◽  
Chaohui He ◽  
Huan He ◽  
Shang Tian ◽  
Yurong Bai
Keyword(s):  
Heat Capacity ◽  
Coupling Factor ◽  
Phonon Coupling ◽  
Electron Heat Capacity ◽  
Electron Heat ◽  
Electron Phonon Coupling

Contributions of Inter- and Intraband Excitations to Electron Heat Capacity and Electron-Phonon Coupling in Noble Metals

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Patrick E. Hopkins
Keyword(s):  
Heat Capacity ◽  
Thermophysical Properties ◽  
Fermi Energy ◽  
Noble Metals ◽  
Coupling Factor ◽  
Energy Separation ◽  
Phonon Coupling ◽  
Electron Heat Capacity ◽  
Electron Heat ◽  
Electron Phonon Coupling

This work examines the effects of photonically induced interband excitations from the d-band to states at the Fermi energy on thermophysical properties in noble metals. The change in the electron population in the d-band and the conduction band causes a change in electron heat capacity and electron-phonon coupling factor, which in turn impacts the evolution of the temperature after pulse absorption and electron thermalization. Expressions for heat capacity and electron-phonon coupling factor are derived for electrons undergoing both inter- and intraband transitions. In noble metals, due to the large d-band to Fermi energy separation, the contributions to electron heat capacity and electron-phonon coupling factor of intra- and interband transitions can be separated. At high absorbed laser fluences and pulse energies greater than the interband transition threshold, the interband and intraband contributions to thermophysical properties differ.

The Role of Thermal Excitation of D Band Electrons in Ultrafast Laser Interaction With Noble (Cu) and Transition (Pt) Metals

2007 ◽  
Author(s):  
Zhibin Lin ◽  
Leonid V. Zhigilei
Keyword(s):  
Heat Capacity ◽  
Coupling Factor ◽  
Ultrafast Laser ◽  
Thermal Excitation ◽  
Phonon Coupling ◽  
Laser Interaction ◽  
Electron Heat Capacity ◽  
Electron Heat ◽  
Electron Phonon Coupling ◽  
Temperature Dependences

The temperature dependences of the electron heat capacity and electron-phonon coupling factor for noble (Cu) and transition (Pt) metals are investigated based on the electron density of states (DOS) obtained from ab initio electronic structure calculations. For Cu, d band electrons could be thermally excited when the electron temperature exceeds ∼3000 K, leading to a significant increase, up to an order of magnitude, in the electron-phonon coupling factor and strong enhancement of the electron heat capacity away from the linear dependence on the electron temperature, which is commonly used in most of the current computational and theoretical investigations of ultrafast laser interactions with metals. Opposite to the case in Cu, the thermal excitation of d band electrons in Pt leads to a monotonic decrease of the electron-phonon coupling factor and contributes to significant negative deviations of the electron heat capacity from the linear dependence in the range of electron temperatures that are typically realized in ultrafast laser material processing applications. Strong and drastically different temperature dependences of the thermophysical properties predicted for Cu and Pt point to the importance of the electron DOS effects and the necessity of full consideration of thermal excitation of d band electrons for realistic modeling of short pulse laser interaction with noble and transition metals.

Electron–Phonon Coupled Heat Transfer and Thermal Response Induced by Femtosecond Laser Heating of Gold

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Pengfei Ji ◽  
Yuwen Zhang
Keyword(s):  
Heat Transfer ◽  
Femtosecond Laser ◽  
Density Functional ◽  
Energy Transport ◽  
Thermal Response ◽  
Coupling Factor ◽  
Heat Transfer Process ◽  
Thermal Excitation ◽  
Coupled Heat Transfer ◽  
Electron Heat Capacity

Ab initio simulation is one of the most effective theoretical tools to study the electrons evolved heat transfer process. Here, we report the use of finite-temperature density functional theory (DFT) to investigate the electron thermal excitation, electron–phonon coupled heat transfer, and the corresponding thermal response induced by energy deposition of femtosecond laser pulse in gold. The calculated results for cases with different scales of electron excitations demonstrate significant electron temperature dependence of electron heat capacity and electron–phonon coupling factor. Bond hardening of laser-irradiated gold and structural variation from solid to liquid are observed. The obtained results shed light upon the ultrafast microscopic processes of thermal energy transport from electron subsystem to lattice subsystem and serve for an improved interpretation of femtosecond laser–metal interaction.

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