光子学的进展

光子学的概念 爱因斯坦在1905年就提出了光子的概念,1917年又提出了原子系统中光子不仅有自发发射而且还有受激发射的假设。爱因斯坦的光子学说促进了光学和光电子学的发展,为激光的出现奠定了理论基础。60年代激光的出现,便以光子为主体的光子学走上了快速发展的道路。

Effect of Pressure on Electronic Structures and Optical Properties of Rocksalt InN

The electronic structures and optical properties of rocksalt indium nitride （INN） under pressure were studied using the first-principles calculation by considering the exchange and correlation potentials with the generalized gradient approximation. The calculated lattice constant shows good agreement with the experimental value. It is interestingly found that the band gap energy Eg at the F or X point remarkably increases with increasing pressure, but Eg at the L point does not increase obviously. The pressure coefficient of Eg is calculated to be 44 meV/GPa at the F point. Moreover, the optical properties of rocksalt InN were calculated and discussed based on the calculated band structures and electronic density of states.

Study of the Bc—Meson Lifetime

We in terms of optical theorem estimate the lifetime of Bc meson with the parameters which are determined by fitting the data for the lifetimes and inclusive semileptonic decays of various B and D mesons. In the estimation, we find that the bound-state effects are important, and take them into account carefully in the framework which attributes the effects to the effective masses of the decay heavy quarks in the inclusive processes. We also find that to Bc lifetime the penguin contribution is enhanced due to possible interference between the penguin and the 'tree part' c1O1 + c2O2.

N = 4 Supersymmetric Morse Oscillator and Its Spectrum-Generating Algebra

In this paper N = 4 supersymmetry of generalized Morse oscillators in one dimension is studied. Both bound states and scattering states of its four superpartner Hamiltonians are analyzed by using unitary irreducible representations of the noncompact Lie algebra su(1,1). The spectrum-generating algebra governing the Hamiltonian of the N = 4 supersymmetric Morse oscillator is shown to be connected with the realization of Lie superalgebra osp(1,2)or B(0,1) in terms of the variables of a supersymmetric two-dimensional harmonic oscillator.

Interferences in Photodetachment of a Negative Molecular Ion Model

By employing a two-center model, the total and differential cross sections in the photodetachment of ＂a negative molecular ion＂ are studied theoreticedly and obtained for the case of light polarization paredlel to the molecular axis. We find that in contrast to the smooth behavior of the total cross section for perpendicular polarized light, the cross section for parallel polarized light shows an interesting oscillatory structure. The oscillations in the toted cross section may provide a method to determine the distance between the two centers. We explain the oscillation in the toted cross section as an interference effect using closed-orbit theory. We also cedculated the detached-electron flux distributions on a screen placed at a large distance from the negative molecular ion. The distributions display multiple-ring-like interference patterns. Such interference patterns are similar to those in the photodetachment microscopy experiments.

Quantum theory analysis of the action micromechanism exerted on bioparticles from laser microbeams

The effect of laser microbeam trapping the bioparticles has been appfied widely in the biology .However the micromechanism of the acting that realizes the laser-microbeam trapping bioparticles is still lacking. In this paper ,the act microchenism of the gradiant force of laser microbeam for the bioparticles is analysed by means of quantum theory ,The result accords with our experiment.

Raman Theory for a molecule in a Vibrating Microcavity Oscillating in Fundamental Resonance

We propose a model to describe the energy structure and dynamics of a system of a molecule interacting with infinite photon modes in a vibrating microcavity whose boundary oscillates in the fundamental resonance. By constructing an Lie algebra for the infinite photon modes, we obtain analytical expressions of the energy eigenstates, energy eigenvalues and the system's evolution operator for this Raman model under certain conditions.

Anomalous Optical and Electronic Properties of CaTiO3 Perovskites

With the help of the first-prlnciples full potential linearized augmented plane wave method, absorption coefficients, reflect/vity, dielectric behavior and electronic properties, including electronic energy bands, density of states and charge density distributions, are studied for the tetragonal and cubic CaTiO3. By considering the thermal expansion effects, an approximate method is proposed for the study of the stability of ground state and a tendency of phase transition, based on the minimum free energy principle. Subsequently, numerical calculations are carried out by using the first-principles perturbation method. We demonstrate that the high-temperature phase is cubic. It is shown that optical spectra in tetragonal phase exhibit single-peak feature and differ from multi-peak character in cubic. We find that strong orbital hybridization results in the co-valent bonds between Ti 3d and O 2p electrons and forms two-type dipoles （Ti-Ol and Ti-02） in tetragonal, while the Ti-O dipoles are identical in cubic. It is argued that crystal structure determines the dipole distributions and leads to some electron states among which the dipole-dipole transit/on forbidden is a key, causing such anomalous optical phenomena with the insulator characteristics. The predicted charge density distribution and the tendency of phase transition from tetragonal to cubic are in good agreement with experimental observations.

Conformations and Structures of Ethoxycarbonyl Isothiocyanate Revealed by Rotational Spectroscopy

The ethoxycarbonyl isothiocyanate has been investigated by using supersonic jet Fourier transform microwave spectroscopy.Two sets of rotational spectra belonging to conformers TCC(with the backbone of C-C-O-C,C-O-C=O,and O-C(=O)-NCS being trans,cis,and cis arranged,respectively)and GCC(gauche,cis,and cis arrangement of the C-C-O-C,C-O-C=O,and O-C(=O)-NCS)have been measured and assigned.The measurements of13C,15N and34S mono-substituted species of the two conformers have also been performed.The comprehensive rotational spectroscopic investigations provide accurate values of rotational constants and14N quadrupole coupling constants,which lead to structural determinations of the two conformers of ethoxycarbonyl isothiocyanate.For conformer TCC,the values of Pcckeep constant upon isotopic substitution,indicating that the heavy atoms of TCC are effectively located in the ab plane.

Electronic and Optical Properties of Cubic SrHfO_3

In order to clarify the mechanism of optical transitions for cubic SrHfO_3, we have investigated the electronicstructure and optical properties of cubic SrHfO_3 using the plane-wave ultrasoft pseudopotential technique based on thefirst-principles density-functional theory (DFT).The ground-state properties, obtained by minimizing the total energy,are in favorable agreement with the previous work.From the band structure and charge densities as well as the theoryof crystal-field and molecular-orbital bonding, we have systematically studied how the optical transitions are affected bythe electronic structure and molecular orbitals.Our calculated complex dielectric function is in good agreement withthe experimental data and the optical transitions are in accord with the electronic structure.

Electronic and optical properties of anion-doped c-ZrO_2 from first-principles calculations

Using the first-principles calculations based on density functional theory(DFT),the structure stability,electronic and some optical properties of C and N doped cubic ZrO2(c-ZrO2) in 24-atom systems were investigated.It is found from the formation energies calculations that N ions are easier to be doped into c-ZrO2 than C ions.The electronic structure results show that Zr8O15C and Zr8O15N systems are semiconductors with the band gap of 2.3 eV and 2.8 eV,respectively,which are lower than that of the pure ZrO2(3.349 eV).And optical properties results depict that anion doping,especially C adding,can enhance the static dielectric function,visible and ultraviolet light absorption and reflecting ability of c-ZrO2 crystal.

Physically-based modeling for hole scattering rate in strained Si_(1-x) Ge_x/(100)Si

Based on the Fermi's golden rule and the theory of Boltzmann collision term approximation, a physically-based model for hole scattering rate(SR) in strained Si1-x Gex/(100)Si was presented, which takes into account a variety of scattering mechanisms,including ionized impurity, acoustic phonon, non-polar optical phonon and alloy disorder scattering. It is indicated that the SRs of acoustic phonon and non-polar optical phonon decrease under the strain, and the total SR in strained Si1-x Gex/(100)Si also decreases obviously with increasing Ge fraction(x). Moreover, the total SR continues to show a constant tendency when x is less than 0.3. In comparison with bulk Si, the total SR of strained Si1-x Gex/(100) Si decreases by about 58%.

New Operator Identity Derived by IWOP Technique and Its Application in Claculating Photocount Distribution

Using the technique of integration within an antinormally ordered product of operators we present a convenient approach for deriving some new operator identities in quantum optics theory. Based on P-representation we also derive a new formula for evaluating photocount distribution.

Two designs of thin film for cooling buildings based on photonic crystal

Nowadays, air conditioning, a relatively energy-intensive method, is still the main way to cooling buildings. This paper proposes two designs of thin film which uses photonic crystal and is based on theories of black-body radiation and electrodynamics. By different designs, the two thin films have disparate photonic band gap, making them respectively suitable for wall and windows. As a new type of material for buildings, it has distinguished advantages of low-energy consumption and high efficiency.

Grey hematite photoanodes decrease the onset potential in photoelectrochemical water oxidation

Photoelectrochemical(PEC)water splitting for solar energy conversion into chemical fuels has attracted intense research attention.The semiconductor hematite(α-Fe_(2)O_(3)),with its earth abundance,chemical stability,and efficient light harvesting,stands out as a promising photoanode material.Unfortunately,its electron affinity is too deep for overall water splitting,requiring additional bias.Interface engineering has been used to reduce the onset potential of hematite photoelectrode.Here we focus instead on energy band engineering hematite by shrinking the crystal lattice,and the water-splitting onset potential can be decreased from 1.14 to 0.61 V vs.the reversible hydrogen electrode.It is the lowest record reported for a pristine hematite photoanode without surface modification.X-ray absorption spectroscopy and magnetic properties suggest the redistribution of 3d electrons in the as-synthesized grey hematite electrode.Density function theory studies herein show that the smaller-lattice-constant hematite benefits from raised energy bands,which accounts for the reduced onset potential.

A first-principles study of dihydroazulene as a possible optical molecular switch

By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of the dihydroazulene optical molecular switch. Three kinds of adsorption sites including the hollow, bridge and top sites are studied. The two forms of this molecule, namely the open form and the closed form, can reversibly switch from each other upon photoexcitation. Their transmission spectra are remarkably distinctive. Theoretical results show that the current of the closed form is always significantly larger than that of the open form for all three adsorption sites, which promises this system as possibly one of the good candidates for optical switches due to its unique advantage, and which may have some potential applications in the future molecular circuit.

Hole scattering mechanism of strained Si/(111)Si_(1-x)Ge_x

Based on Fermi’s golden rule and the theory of Boltzmann collision term approximation, the hole scattering mechanism ofstrained Si/(111)Si1 xGexwas established, including ionized impurity, acoustic phonon, non-polar optical phonon and totalscattering rate models. It was found that the total scattering rate of the hole in strained Si/(111)Si1 xGexdecreased obviouslywith the increasing stress when energy was 0.04 eV. In comparison with one of the unstrained Si, the total hole scattering rateof strained Si/(111)Si1 xGexdecreased about 38% at most. The decreasing hole scattering rate enhanced the hole mobility instrained Si materials. The result could provide valuable references to the research on hole mobility of strained Si materials andthe design of PMOS devices.

First-Principles Calculations on Electronic,Chemical Bonding and Optical Properties of Cubic Hf_3N_4

Electronic, chemicM bonding and optical properties of cubic Hf3N4 （ c-Hf3N4 ） are calculated using the first- principles based on the density functional theory （DFT）. The optimized lattice parameter is in good agreement with the available experimental and cedculational values. Band structure shows that c-Hf3N4 has direct band gap. Densities of states （DOS） and charge densities indicate that the bonding between Hf and N is ionic. The optical properties including complex dielectric function, refractive index, extinction coefficient, absorption coefficient, and refleetivity are predicted. Prom the theory of crystal-field and molecular-orbited bonding, the optical transitions of c-Hf3N4 affected by the electronic structure and molecular orbited are studied. It is found that the absorptive transitions of c-Hf3N4 compound are predominantly composed of the transitions from N T2 2p valence bands to Hf T2 （dxy, dxz, dyz） conduction bands.