The creation and propagation of longitudinal acoustic phonons （LAPs） in high quality hematite thin films （α-Fe203） epitaxially grown on different substrates （BaTiO3, SrTiO3, and LaAlO3） are investigated using t...The creation and propagation of longitudinal acoustic phonons （LAPs） in high quality hematite thin films （α-Fe203） epitaxially grown on different substrates （BaTiO3, SrTiO3, and LaAlO3） are investigated using the femtosecond pump- probe technique. Transient reflection measurements （AR/R） indicate the photo-excited electron dynamics, and the initial decay less than 1 ps and the slow decay of -500 ps are attributed to the electron-LO phonon coupling and electron-hole nonradiative recombination, respectively. LAPs in α-Fe2O3 film can be created by ultrafast excitation of the ligand field state, such as the ligand field transitions under 800-nm excitation as well as the ligand to metal charge-transfer with 400- nm excitation. The strain modulations of the sound velocity and the out-of-plane elastic properties are demonstrated in α-Fe2O3 film on different substrates.展开更多
I.THEORY The Hamiltonian of rare earth ions can be written as where （?）<sub>Coul</sub> is the Coulomb interaction, （?）<sub>s·o</sub>, the spin-orbit interaction, （?）<sub>Ca<...I.THEORY The Hamiltonian of rare earth ions can be written as where （?）<sub>Coul</sub> is the Coulomb interaction, （?）<sub>s·o</sub>, the spin-orbit interaction, （?）<sub>Ca</sub>, Casimir operator interaction in the interaction of different configurations in Coulomb interaction, and （?）<sub>cf</sub> is ligand field interaction. A method to treat the rare earth ions is to diagonalize （?）<sub>Coul</sub>, （?）<sub>s.o</sub> and （?）<sub>Ca</sub>, in （1） simultaneously and then to determine the eigenfunction of "展开更多
The photoelectron imagings of LaO-, CeO-, PRO-, and NdO- at 1064 nm are reported. The well resolved photoelectron spectra allow the electron affinities to be determined as 0.99（1） eV for LaO, 1.00（1） eV for CeO, 1...The photoelectron imagings of LaO-, CeO-, PRO-, and NdO- at 1064 nm are reported. The well resolved photoelectron spectra allow the electron affinities to be determined as 0.99（1） eV for LaO, 1.00（1） eV for CeO, 1.00（1） eV for PrO, and 1.01（1） eV for NdO, respectively. Density functional calculations and natural atomic orbital analyses show that the 4f electrons tend to be localized and suffer little from the charge states of the molecules. The photodetached electron mainly originates from the 6s orbital of the metals. The ligand field theory with the δ=2 assumption is still an effective method to analyze the ground states of the neutral and anionic lanthanide monoxides.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11174195)
文摘The creation and propagation of longitudinal acoustic phonons （LAPs） in high quality hematite thin films （α-Fe203） epitaxially grown on different substrates （BaTiO3, SrTiO3, and LaAlO3） are investigated using the femtosecond pump- probe technique. Transient reflection measurements （AR/R） indicate the photo-excited electron dynamics, and the initial decay less than 1 ps and the slow decay of -500 ps are attributed to the electron-LO phonon coupling and electron-hole nonradiative recombination, respectively. LAPs in α-Fe2O3 film can be created by ultrafast excitation of the ligand field state, such as the ligand field transitions under 800-nm excitation as well as the ligand to metal charge-transfer with 400- nm excitation. The strain modulations of the sound velocity and the out-of-plane elastic properties are demonstrated in α-Fe2O3 film on different substrates.
文摘I.THEORY The Hamiltonian of rare earth ions can be written as where （?）<sub>Coul</sub> is the Coulomb interaction, （?）<sub>s·o</sub>, the spin-orbit interaction, （?）<sub>Ca</sub>, Casimir operator interaction in the interaction of different configurations in Coulomb interaction, and （?）<sub>cf</sub> is ligand field interaction. A method to treat the rare earth ions is to diagonalize （?）<sub>Coul</sub>, （?）<sub>s.o</sub> and （?）<sub>Ca</sub>, in （1） simultaneously and then to determine the eigenfunction of "
基金This work was supported by the National Natural Science Foundation of China （No.20933003） and the National Basic Research Program of China （No.2010CB732306）.
文摘The photoelectron imagings of LaO-, CeO-, PRO-, and NdO- at 1064 nm are reported. The well resolved photoelectron spectra allow the electron affinities to be determined as 0.99（1） eV for LaO, 1.00（1） eV for CeO, 1.00（1） eV for PrO, and 1.01（1） eV for NdO, respectively. Density functional calculations and natural atomic orbital analyses show that the 4f electrons tend to be localized and suffer little from the charge states of the molecules. The photodetached electron mainly originates from the 6s orbital of the metals. The ligand field theory with the δ=2 assumption is still an effective method to analyze the ground states of the neutral and anionic lanthanide monoxides.
