Improved Two-Temperature Model and Its Application in Ultrashort Laser Heating of Metal Films

2005 ◽  
Vol 127 (10) ◽  
pp. 1167-1173 ◽  
Author(s):  
Lan Jiang ◽  
Hai-Lung Tsai
Keyword(s):  
High Electron ◽  
Temperature Model ◽  
Laser Fluences ◽  
Electron Heat Capacity ◽  
Fermi Temperature ◽  
Proposed Model ◽  
Electron Relaxation ◽  
Electron Relaxation Time ◽  
Ultrashort Laser ◽  
Two Temperature

The two-temperature model has been widely used to predict the electron and phonon temperature distributions in ultrashort laser processing of metals. However, estimations of some important thermal and optical properties in the existing two-temperature model are limited to low laser fluences in which the electron temperatures are much lower than the Fermi temperature. This paper extends the existing two-temperature model to high electron temperatures by using full-run quantum treatments to calculate the significantly varying properties, including the electron heat capacity, electron relaxation time, electron conductivity, reflectivity, and absorption coefficient. The proposed model predicts the damage thresholds more accurately than the existing model for gold films when compared with published experimental results.

scholarly journals TWO-TEMPERATURE MODEL OF NONEQUILIBRIUM ELECTRON RELAXATION: A REVIEW

2010 ◽  
Vol 24 (09) ◽  
pp. 1141-1158 ◽  
Author(s):  
NAVINDER SINGH
Keyword(s):  
Electronic Relaxation ◽  
Temperature Model ◽  
Open Problems ◽  
Nonequilibrium Electron ◽  
Pump Probe ◽  
Nano Scale ◽  
Electron Relaxation ◽  
Probe Spectroscopy ◽  
Kinetics Of ◽  
Two Temperature

The present paper is a review of the phenomena related to nonequilibrium electron relaxation in bulk and nano-scale metallic samples. The workable Two-Temperature Model (TTM) based on Boltzmann–Bloch–Peierls kinetic equation has been applied to study the ultra-fast (femto-second) electronic relaxation in various metallic systems. The advent of new ultra-fast (femto-second) laser technology and pump-probe spectroscopy has produced wealth of new results for micro- and nano-scale electronic technology. The aim of this paper is to clarify the TTM, conditions of its validity and nonvalidity, its modifications for nano-systems, to sum-up the progress, and to point out open problems in this field. We also give a phenomenological integro-differential equation for the kinetics of nondegenerate electrons that goes beyond the TTM.

scholarly journals Nonequilibrium electron relaxation in graphene

2019 ◽  
Vol 33 (17) ◽  
pp. 1950183
Author(s):  
Luxmi Rani ◽  
Pankaj Bhalla ◽  
Navinder Singh
Keyword(s):  
Memory Function ◽  
Temperature Model ◽  
Experimental Setting ◽  
Finite Frequency ◽  
Nonequilibrium Electron ◽  
Pump Probe ◽  
Scattering Rate ◽  
Electron Relaxation ◽  
Frequency Regime ◽  
Two Temperature

We apply memory function formalism to investigate nonequilibrium electron relaxation in graphene. Within the premises of two-temperature model (TTM), explicit expressions of the imaginary part of the memory function or generalized Drude scattering rate (1/[Formula: see text]) are obtained. In the DC limit and in equilibrium case where electron temperature (Te) is equal to phonon temperature (T), we reproduce the known results (i.e., 1/[Formula: see text][Formula: see text]T4 when T[Formula: see text][Formula: see text] and 1/[Formula: see text][Formula: see text]T when T[Formula: see text][Formula: see text], where [Formula: see text] is the Bloch–Grüneisen temperature). We report several new results for 1/[Formula: see text] where T[Formula: see text][Formula: see text][Formula: see text]Te relevant in pump–probe spectroscopic experiments. In the finite-frequency regime we find that 1/[Formula: see text] when [Formula: see text], and for [Formula: see text] it is [Formula: see text]-independent. These results can be verified in a typical pump–probe experimental setting for graphene.

scholarly journals Ultrashort Laser Pulse Heating of Nanoparticles: Comparison of Theoretical Approaches

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Renat R. Letfullin ◽  
Thomas F. George ◽  
Galen C. Duree ◽  
Brett M. Bollinger
Keyword(s):  
Laser Pulse ◽  
Laser Heating ◽  
Cell Damage ◽  
Heat Diffusion ◽  
Temperature Model ◽  
Particle Volume ◽  
Heat Diffusion Equation ◽  
Theoretical Approaches ◽  
Ultrashort Laser ◽  
Two Temperature

The interaction between nanoparticles and ultrashort laser pulses holds great interest in laser nanomedicine, introducing such possibilities as selective cell targeting to create highly localized cell damage. Two models are studied to describe the laser pulse interaction with nanoparticles in the femtosecond, picosecond, and nanosecond regimes. The first is a two-temperature model using two coupled diffusion equations: one describing the heat conduction of electrons, and the other that of the lattice. The second model is a one-temperature model utilizing a heat diffusion equation for the phonon subsystem and applying a uniform heating approximation throughout the particle volume. A comparison of the two modeling strategies shows that the two-temperature model gives a good approximation for the femtosecond mode, but fails to accurately describe the laser heating for longer pulses. On the contrary, the simpler one-temperature model provides an adequate description of the laser heating of nanoparticles in the femtosecond, picosecond, and nanosecond modes.

scholarly journals Investigation of heat transfer in metal nanofilms irradiated with ultrashort laser pulses: two-temperature model

2021 ◽  
Vol 2094 (2) ◽  
pp. 022023
Author(s):  
G V Mikheeva ◽  
A V Pashin
Keyword(s):  
Heat Transfer ◽  
Crystal Lattice ◽  
Ultrashort Laser Pulse ◽  
Numerical Study ◽  
Laser Pulses ◽  
Equilibrium Temperature ◽  
Ultrashort Laser Pulses ◽  
Temperature Model ◽  
Ultrashort Laser ◽  
Two Temperature

Abstract A numerical study of heat transfer between an electron gas and a crystal lattice in a metal nanofilm under irradiation with an ultrashort laser pulse was carried out on the basis of a parabolic two-temperature model of thermal conductivity presented in a dimensionless form. For the numerical solution, the finite difference method was used using the explicit-implicit Crank-Nicholson scheme. As a result of the numerical study, it was found that with an increase in the thickness of the plate, the equilibrium temperature decreases, and the time for the onset of thermal equilibrium between the electrons and the crystal lattice increases.

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