A brief review of Huang–Rhys theory and Albrechtos theory is provided,and their connection and applications are discussed.The former is a first order perturbative theory on optical transitions intended for applicatio...A brief review of Huang–Rhys theory and Albrechtos theory is provided,and their connection and applications are discussed.The former is a first order perturbative theory on optical transitions intended for applications such as absorption and emission involving localized defect or impurity centers,emphasizing lattice relaxation or mixing of vibrational states due to electron–phonon coupling.The coupling strength is described by the Huang–Rhys factor.The latter theory is a second order perturbative theory on optical transitions intended for Raman scattering,and can in-principle include electron–phonon coupling in both electronic states and vibrational states.These two theories can potentially be connected through the common effect of lattice relaxation – non-orthonormal vibrational states associated with different electronic states.Because of this perceived connection,the latter theory is often used to explain resonant Raman scattering of LO phonons in bulk semiconductors and further used to describe the size dependence of electron–phonon coupling or Huang–Rhys factor in semiconductor nanostructures.Specifically,the A term in Albrechtos theory is often invoked to describe the multi-LO-phonon resonant Raman peaks in both bulk and nanostructured semiconductors in the literature,due to the misconception that a free-exciton could have a strong lattice relaxation.Without lattice relaxation,the A term will give rise to Rayleigh or elastic scattering.Lattice relaxation is only significant for highly localized defect or impurity states,and should be practically zero for either single particle states or free exciton states in a bulk semiconductor or for confined states in a semiconductor nanostructure that is not extremely small.展开更多
This paper examines the identity crisis experienced by Antoinette in Jean Rhys’ Wide Sargasso Sea (1966) from a predominantly soci-psychological perspective. Since most of the critical attention regarding Wide Sargas...This paper examines the identity crisis experienced by Antoinette in Jean Rhys’ Wide Sargasso Sea (1966) from a predominantly soci-psychological perspective. Since most of the critical attention regarding Wide Sargasso Sea has been devoted to external problems, such as race, gender and colonial politics, this article will concentrate on the psychological relevance of those issues, examining the reasons for the internal conflict and sharp divisions that torment the heroine. It investigates identity crisis faced by the novel’s heroine and her struggle to overcome this crisis in a society where woman is triply marginalized by race, class, gender and colonialism. It also traces Antoinette’s search and struggle for an independent life and examines the extent to which she succeeds or fails in articulating her identity. Special emphasis will be laid on Erik Erikson’s psychological theories of identity crisis and human development. The paper depicts the protagonist’s endeavour to overcome the external forces that impact the construction or destruction of her identity. Ultimately, Antoinette reaches a resolution on her own terms,depending on her own personal decision and the surrounding societal and cultural circumstances.展开更多
We develop in this paper the theory of multiphonon radiative transition so that someimportant physical quantities that describe effect s of lattice relaxation in electron transitions,for example, Huang--Rhys parameter...We develop in this paper the theory of multiphonon radiative transition so that someimportant physical quantities that describe effect s of lattice relaxation in electron transitions,for example, Huang--Rhys parameters, lattice relaxation energies and Stokes shifts, becomecomputable directly. The calculated results of the se physical quantities for alexandrite agreewith experimental data very well. Besides, we deduce expressions of intensity distributionand integrated intensity of a multiphonon sideband in non--Condon approximation. The cal-culated values of integrated intensities are obviously better than the intensity fitting resultsof previous work. From these calculated values we can also acquire a quantitative under-standing of the errors of Condon approximation.展开更多
This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence （PL） measurements. With increasing cap la...This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence （PL） measurements. With increasing cap layer thickness, the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal- optical （LO） phonon, described by Huang-Rhys factor, increases remarkably due to an enhancement of the internal electric field. With increasing excitation intensity, the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases. These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer.展开更多
文摘A brief review of Huang–Rhys theory and Albrechtos theory is provided,and their connection and applications are discussed.The former is a first order perturbative theory on optical transitions intended for applications such as absorption and emission involving localized defect or impurity centers,emphasizing lattice relaxation or mixing of vibrational states due to electron–phonon coupling.The coupling strength is described by the Huang–Rhys factor.The latter theory is a second order perturbative theory on optical transitions intended for Raman scattering,and can in-principle include electron–phonon coupling in both electronic states and vibrational states.These two theories can potentially be connected through the common effect of lattice relaxation – non-orthonormal vibrational states associated with different electronic states.Because of this perceived connection,the latter theory is often used to explain resonant Raman scattering of LO phonons in bulk semiconductors and further used to describe the size dependence of electron–phonon coupling or Huang–Rhys factor in semiconductor nanostructures.Specifically,the A term in Albrechtos theory is often invoked to describe the multi-LO-phonon resonant Raman peaks in both bulk and nanostructured semiconductors in the literature,due to the misconception that a free-exciton could have a strong lattice relaxation.Without lattice relaxation,the A term will give rise to Rayleigh or elastic scattering.Lattice relaxation is only significant for highly localized defect or impurity states,and should be practically zero for either single particle states or free exciton states in a bulk semiconductor or for confined states in a semiconductor nanostructure that is not extremely small.
文摘This paper examines the identity crisis experienced by Antoinette in Jean Rhys’ Wide Sargasso Sea (1966) from a predominantly soci-psychological perspective. Since most of the critical attention regarding Wide Sargasso Sea has been devoted to external problems, such as race, gender and colonial politics, this article will concentrate on the psychological relevance of those issues, examining the reasons for the internal conflict and sharp divisions that torment the heroine. It investigates identity crisis faced by the novel’s heroine and her struggle to overcome this crisis in a society where woman is triply marginalized by race, class, gender and colonialism. It also traces Antoinette’s search and struggle for an independent life and examines the extent to which she succeeds or fails in articulating her identity. Special emphasis will be laid on Erik Erikson’s psychological theories of identity crisis and human development. The paper depicts the protagonist’s endeavour to overcome the external forces that impact the construction or destruction of her identity. Ultimately, Antoinette reaches a resolution on her own terms,depending on her own personal decision and the surrounding societal and cultural circumstances.
文摘We develop in this paper the theory of multiphonon radiative transition so that someimportant physical quantities that describe effect s of lattice relaxation in electron transitions,for example, Huang--Rhys parameters, lattice relaxation energies and Stokes shifts, becomecomputable directly. The calculated results of the se physical quantities for alexandrite agreewith experimental data very well. Besides, we deduce expressions of intensity distributionand integrated intensity of a multiphonon sideband in non--Condon approximation. The cal-culated values of integrated intensities are obviously better than the intensity fitting resultsof previous work. From these calculated values we can also acquire a quantitative under-standing of the errors of Condon approximation.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60876007 and 10974165)the Research Program of Xiamen Municipal Science and Technology Bureau,China (Grant No. 2006AA03Z110)
文摘This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence （PL） measurements. With increasing cap layer thickness, the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal- optical （LO） phonon, described by Huang-Rhys factor, increases remarkably due to an enhancement of the internal electric field. With increasing excitation intensity, the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases. These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer.
