In the present paper are reported the OH…O out-of-plane bending band[γ(OH)] between 900—950 cm -1 of dimethylol propionic acid(DMPA), its dependence upon temperature and its overtone band investigated via FTIR s...In the present paper are reported the OH…O out-of-plane bending band[γ(OH)] between 900—950 cm -1 of dimethylol propionic acid(DMPA), its dependence upon temperature and its overtone band investigated via FTIR spectroscopy. It has been found based on the crystal structure that the band [γ(OH)] may not certainly be the characteristic band of carboxylic dimers, it can also result from another H-bond formed between carboxylic carbonyl and the primary hydroxyl. In addition, the band [γ(OH)] is very sensitive to temperature change but its overtone band can only appear at a low temperature.展开更多
Measurement of the Surface Photovoltage Spectra(SPS) of Mo/Bi series catalysts BixPMo12Oy(x= 2～ 9, y= 43～ 64) showed that with the increase of Bi/P molar ratio, SPS exhibits some changes characteristic of modulated ...Measurement of the Surface Photovoltage Spectra(SPS) of Mo/Bi series catalysts BixPMo12Oy(x= 2～ 9, y= 43～ 64) showed that with the increase of Bi/P molar ratio, SPS exhibits some changes characteristic of modulated surface band bendings. The phenomena were explained in terms of the basic capacity of vacancies in the scheelite-type structure of the catalysts.展开更多
By using scanning tunneling microscope/microscopy(STM/STS), we reveal the detailed electronic structures around the sharp edges and strained terraces of lateral monolayer-bilayer Pd_(2)Se_(3) heterostructures. We find...By using scanning tunneling microscope/microscopy(STM/STS), we reveal the detailed electronic structures around the sharp edges and strained terraces of lateral monolayer-bilayer Pd_(2)Se_(3) heterostructures. We find that the edges of such heterostructures are well-defined zigzag type. Band bending and alignment are observed across the zigzag edge, forming a monolayer-bilayer heterojunction. In addition, an n-type band bending is induced by strain on a confined bilayer Pd_(2)Se_(3) terrace. These results provide effective toolsets to tune the band structures in Pd_(2)Se_(3)-based heterostructures and devices.展开更多
The electric band energy variation in a bent piezoelectric semiconductor(PSC) nanowire of circular cross-section induced by the mechanical force is analyzed based on a six-band k · p method. The electric-mechanic...The electric band energy variation in a bent piezoelectric semiconductor(PSC) nanowire of circular cross-section induced by the mechanical force is analyzed based on a six-band k · p method. The electric-mechanical fields are first obtained analytically in a cantilever bent PSC nanowire by solving the fully-coupled electro-mechanical equations. Then, the band energy is acquired numerically via the six-band Hamiltonian.By considering further the nonlinear coupling between the piezoelectric and semiconducting quantities, the contribution of the redistribution carriers to the electric field is analyzed from the Gauss’ s law. Numerical examples are carried out for an n-type Zn O nanowire in different locations induced by an applied concentrated end force. They include the electric potential, heavy hole(HH), light hole(LH), spin-orbit split-off(SO),and conduction band(CB) edges along the axial and thickness directions. Our results show that the applied force has a significant effect on the band energies. For instance, on the bottom surface along the axial direction, the bandgaps near the fixed end are greater than those near the loading end, and this trend is reversed on the top surface. Moreover,at a fixed axial location, the energy level of the lower side can be enhanced by applying a bending force at the end. The present results could be of significant guidance to the electronic devices and piezotronics.展开更多
The dangling bond free nature of two-dimensional(2D)material surface/interface makes van der Waals(vdW)heterostructure attractive for novel electronic and optoelectronic applications.But in practice,edge is unavoidabl...The dangling bond free nature of two-dimensional(2D)material surface/interface makes van der Waals(vdW)heterostructure attractive for novel electronic and optoelectronic applications.But in practice,edge is unavoidable and could cause band bending at 2D material edge analog to surface/interface band bending in conventional three-dimensional(3D)materials.Here,we report a first principle simulation on edge band bending of free standing MoS2/WS2 vdW heterojunction.Due to the imbalance charges at edge,S terminated edge causes upward band bending while Mo/W terminated induces downward bending in undoped case.The edge band bending is comparable to band gap and could obviously harm electronic and optoelectronic properties.We also investigate the edge band bending of electrostatic doped heterojunction.N doping raises the edge band whereas p doping causes a decline of edge band.Heavy n doping even reverses the downward edge band bending at Mo/W terminated edge.In contrast,heavy p doping doesn’t invert the upward bending to downward.Comparing with former experiments,the expected band gap narrowing introduced by interlayer potential gradient at edge is not observed in our free-standing structures and suggests substrate’s important role in this imbalance charge induced phenomenon.展开更多
文摘In the present paper are reported the OH…O out-of-plane bending band[γ(OH)] between 900—950 cm -1 of dimethylol propionic acid(DMPA), its dependence upon temperature and its overtone band investigated via FTIR spectroscopy. It has been found based on the crystal structure that the band [γ(OH)] may not certainly be the characteristic band of carboxylic dimers, it can also result from another H-bond formed between carboxylic carbonyl and the primary hydroxyl. In addition, the band [γ(OH)] is very sensitive to temperature change but its overtone band can only appear at a low temperature.
文摘Measurement of the Surface Photovoltage Spectra(SPS) of Mo/Bi series catalysts BixPMo12Oy(x= 2～ 9, y= 43～ 64) showed that with the increase of Bi/P molar ratio, SPS exhibits some changes characteristic of modulated surface band bendings. The phenomena were explained in terms of the basic capacity of vacancies in the scheelite-type structure of the catalysts.
基金Project supported by the National Key Research and Development Project of China(Grant Nos.2016YFA0202300,2018YFA0305800,and 2019YFA0308500)the National Natural Science Foundation of China(Grant Nos.61888102 and 52022105)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB30000000 and XDB28000000)the University of Chinese Academy of Sciences。
文摘By using scanning tunneling microscope/microscopy(STM/STS), we reveal the detailed electronic structures around the sharp edges and strained terraces of lateral monolayer-bilayer Pd_(2)Se_(3) heterostructures. We find that the edges of such heterostructures are well-defined zigzag type. Band bending and alignment are observed across the zigzag edge, forming a monolayer-bilayer heterojunction. In addition, an n-type band bending is induced by strain on a confined bilayer Pd_(2)Se_(3) terrace. These results provide effective toolsets to tune the band structures in Pd_(2)Se_(3)-based heterostructures and devices.
基金Project supported by the National Natural Science Foundation of China(Nos.11972164,11672113,11472182)the Key Laboratory Project of Hubei Province of China(No.2016CFA073)。
文摘The electric band energy variation in a bent piezoelectric semiconductor(PSC) nanowire of circular cross-section induced by the mechanical force is analyzed based on a six-band k · p method. The electric-mechanical fields are first obtained analytically in a cantilever bent PSC nanowire by solving the fully-coupled electro-mechanical equations. Then, the band energy is acquired numerically via the six-band Hamiltonian.By considering further the nonlinear coupling between the piezoelectric and semiconducting quantities, the contribution of the redistribution carriers to the electric field is analyzed from the Gauss’ s law. Numerical examples are carried out for an n-type Zn O nanowire in different locations induced by an applied concentrated end force. They include the electric potential, heavy hole(HH), light hole(LH), spin-orbit split-off(SO),and conduction band(CB) edges along the axial and thickness directions. Our results show that the applied force has a significant effect on the band energies. For instance, on the bottom surface along the axial direction, the bandgaps near the fixed end are greater than those near the loading end, and this trend is reversed on the top surface. Moreover,at a fixed axial location, the energy level of the lower side can be enhanced by applying a bending force at the end. The present results could be of significant guidance to the electronic devices and piezotronics.
基金This work was supported by the National Natural Science Foundation of China(Nos.51991340,51991342,51527802,51972022,51722203,and 51672026)the Overseas Expertise Introduction Projects for Discipline Innovation(No.B14003)+2 种基金the National Key Research and Development Program of China(Nos.2016YFA0202701 and 2018YFA0703503)the Natural Science Foundation of Beijing Municipality(No.Z180011)the Fundamental Research Funds for the Central Universities(Nos.FRF-TP-18-004A2 and FRF-TP-18-001C1).
文摘The dangling bond free nature of two-dimensional(2D)material surface/interface makes van der Waals(vdW)heterostructure attractive for novel electronic and optoelectronic applications.But in practice,edge is unavoidable and could cause band bending at 2D material edge analog to surface/interface band bending in conventional three-dimensional(3D)materials.Here,we report a first principle simulation on edge band bending of free standing MoS2/WS2 vdW heterojunction.Due to the imbalance charges at edge,S terminated edge causes upward band bending while Mo/W terminated induces downward bending in undoped case.The edge band bending is comparable to band gap and could obviously harm electronic and optoelectronic properties.We also investigate the edge band bending of electrostatic doped heterojunction.N doping raises the edge band whereas p doping causes a decline of edge band.Heavy n doping even reverses the downward edge band bending at Mo/W terminated edge.In contrast,heavy p doping doesn’t invert the upward bending to downward.Comparing with former experiments,the expected band gap narrowing introduced by interlayer potential gradient at edge is not observed in our free-standing structures and suggests substrate’s important role in this imbalance charge induced phenomenon.
