In this unified model,we introduce the electron-phonon coupling time(tie) and laser pulse width(tp).For long pulses,it can substitute for the traditional thermal conduction model;while for ultrashort pulses,it can sub...In this unified model,we introduce the electron-phonon coupling time(tie) and laser pulse width(tp).For long pulses,it can substitute for the traditional thermal conduction model;while for ultrashort pulses,it can substitute for the standard two-temperature model.As an example of the gold target,we get the dependence of the electron and ion temperature evolvement on the time and position by solving the thermal conduction equation using the finite-difference time-domain(FDTD) method.It is in good agreement with experimental data.We obtain the critical temperature of the onset of ablation using the Saha equation and then obtain the theoretical value of the laser ablation threshold when the laser pulse width ranges from nano-second to femtosecond timescale,which consists well with the experimental data.展开更多
A new ansatz is presentedfor analytic study of the properties of the Holstein model. New analytic resultsfor the polaronic band structure, ground state energy, phonon distribution, hopping probability of electron, and...A new ansatz is presentedfor analytic study of the properties of the Holstein model. New analytic resultsfor the polaronic band structure, ground state energy, phonon distribution, hopping probability of electron, and effectivemasses, of the Holstein molecular crystal model, are given in one dimension. All the analytic results obtained are inaccord with the numerical results completed recently and valid both in the adiabatic and nonadiabatic regimes, andaccurate enough in the region of validity.展开更多
Under dielectric continuum approximation,interface optical (IO) phonon modes and the Froehlich electron IO phonon interaction Hamiltonian in a multi-shell spherical nanoheterosystem were derived and studied.Numerical ...Under dielectric continuum approximation,interface optical (IO) phonon modes and the Froehlich electron IO phonon interaction Hamiltonian in a multi-shell spherical nanoheterosystem were derived and studied.Numerical calculations on three-layer and four-layer CdS/HgS spherical nanoheterosystems have been performed.Results reveal that there are four IO Phonon modes for the three-layer system and six IO phono modes for the four-layer system.On each interface,there are two IO phonon modes,the frequency of one is between wTO,CdS and ωLO,CdS,and that of the other is between ωTO,HgS and ωLO,HgS.With the increasing of quantum number l,the frequency of each IO mode approaches one of the two frequency values of the single CdS/HgS heterostructure,and the potential for each IO mode is more and more localized at a certain at a certain interface,furthermore,the coupling between the electron-IO phonos becomes weaker.展开更多
By using determinant method as in our recent work, the IO phonon modes, the orthogonal relation for polarization vector, electron-IO phonon F^6hlich interaction Hamiltonian, the dispersion relation, and the electron-p...By using determinant method as in our recent work, the IO phonon modes, the orthogonal relation for polarization vector, electron-IO phonon F^6hlich interaction Hamiltonian, the dispersion relation, and the electron-phonon coupling function in an arbitrary layer-number quantum well system have been derived and investigated within the framework of dielectric continuum approximation. Numerical calculation on seven-layer AlxGal-xAs/GaAs systems have been performed. Via the numerical results in this work and previous works, the general characters of the IO phonon modes in an n-layer coupling quantum well system were concluded and summarized. This work can be regarded as a generalization of previous works on IO phonon modes in some fLxed layer-number quantum well systems, and it provides a uniform method to investittate the effects of IO phonons on the multi-layer coupling quantum well systems.展开更多
基金The project supported by the Science and Technology Project of Adwnced Academy of Guangzhou City under Grant No. 2060, National Natural Science Foundation of China under Grant Nos. 60276004 and 60390073, and the Scientific Research Foundation for the Returned 0verseas Chinese Scholars of the Ministry of Education of China
文摘In this unified model,we introduce the electron-phonon coupling time(tie) and laser pulse width(tp).For long pulses,it can substitute for the traditional thermal conduction model;while for ultrashort pulses,it can substitute for the standard two-temperature model.As an example of the gold target,we get the dependence of the electron and ion temperature evolvement on the time and position by solving the thermal conduction equation using the finite-difference time-domain(FDTD) method.It is in good agreement with experimental data.We obtain the critical temperature of the onset of ablation using the Saha equation and then obtain the theoretical value of the laser ablation threshold when the laser pulse width ranges from nano-second to femtosecond timescale,which consists well with the experimental data.
文摘A new ansatz is presentedfor analytic study of the properties of the Holstein model. New analytic resultsfor the polaronic band structure, ground state energy, phonon distribution, hopping probability of electron, and effectivemasses, of the Holstein molecular crystal model, are given in one dimension. All the analytic results obtained are inaccord with the numerical results completed recently and valid both in the adiabatic and nonadiabatic regimes, andaccurate enough in the region of validity.
文摘Under dielectric continuum approximation,interface optical (IO) phonon modes and the Froehlich electron IO phonon interaction Hamiltonian in a multi-shell spherical nanoheterosystem were derived and studied.Numerical calculations on three-layer and four-layer CdS/HgS spherical nanoheterosystems have been performed.Results reveal that there are four IO Phonon modes for the three-layer system and six IO phono modes for the four-layer system.On each interface,there are two IO phonon modes,the frequency of one is between wTO,CdS and ωLO,CdS,and that of the other is between ωTO,HgS and ωLO,HgS.With the increasing of quantum number l,the frequency of each IO mode approaches one of the two frequency values of the single CdS/HgS heterostructure,and the potential for each IO mode is more and more localized at a certain at a certain interface,furthermore,the coupling between the electron-IO phonos becomes weaker.
文摘By using determinant method as in our recent work, the IO phonon modes, the orthogonal relation for polarization vector, electron-IO phonon F^6hlich interaction Hamiltonian, the dispersion relation, and the electron-phonon coupling function in an arbitrary layer-number quantum well system have been derived and investigated within the framework of dielectric continuum approximation. Numerical calculation on seven-layer AlxGal-xAs/GaAs systems have been performed. Via the numerical results in this work and previous works, the general characters of the IO phonon modes in an n-layer coupling quantum well system were concluded and summarized. This work can be regarded as a generalization of previous works on IO phonon modes in some fLxed layer-number quantum well systems, and it provides a uniform method to investittate the effects of IO phonons on the multi-layer coupling quantum well systems.
