关于使用光谱仪的一些建议

关于使用光谱仪的一些建议肖新民高长连王建模辛建之陶向阳罗宏雷１刘正东２（江西师范大学物理系南昌３３００２７）（１杭州三维高技术产业公司杭州３１００１２）（２浙江大学物理系杭州３１００２７）ＳｏｍｅＳｕｇｇｅｓｔｉｏｎｓｆｏｒＯｐｅｒａｔｉｎｇＳｐｅ...     

两种新合成卟啉的拉曼和表面增强拉曼光谱

两种新合成卟啉的拉曼和表面增强拉曼光谱叶晓岚１邓文杰２梁二军３刘社文３（１．杭州大学化学系杭州３１００２８２．杭州师范大学化学系杭州３１００１２３．郑州大学物理工程学院郑州４５００５２）ＮｏｒｍａｌａｎｄＳｕｒｆａｃｅ┐ＥｎｈａｎｃｅｄＲａｍａｎＳｐ...     

电源输出功率与负载的关系

在纯电阻电路里，电源的输出功率Ｐ＝Ｉ２Ｒ＝（ＥＲ＋ｒ）２·Ｒ＝Ｅ２Ｒ（Ｒ＋ｒ）２．若Ｒ２＞Ｒ１，则ＰＲ２－ＰＲ１＝Ｅ２Ｒ２（Ｒ２＋ｒ）２－Ｅ２Ｒ１（Ｒ１＋ｒ）２＝Ｅ２（Ｒ２－Ｒ１）（Ｒ１＋ｒ）２·（Ｒ２＋ｒ）２·（ｒ２－Ｒ１Ｒ２）由题设条件Ｒ２＞Ｒ１...     

莫塞莱公式与屏蔽常数

本文分析了莫塞莱公式ｖ＝Ｒ（Ｚ－１）２（１／１～２－１／２～２）的近似性质，指出它只对Ｚ＝１７—２８区间的原子才是比较准确的．本文论证了公式中（Ｚ－１）里的数字１不是真正的屏蔽常数σ，从而认为不能把Ｒ（Ｚ－１）２／１～２和Ｒ（Ｚ－１）２／２～２理解成Ｋ与Ｌ光谱项．最后，计算出了Ｋ、Ｌ壳层的屏蔽常数σ、σ．     

电路的等效变换

电路的等效变换王冬梅（浙江省建材工业学校杭州３１００１４）解直流电习题中，电路的等效变换是一难点．在此介绍节点法，画原电路等效电路图．１原理１．１导线电阻可忽略不计，导线两端电势差为零，导线中电势处处相等．１．２电表视为理想电表．安培表内阻为零，可用...     

SCF—Xα—SW程序和LMTO程序的改进及其在固体体系中的应用

在ＹＨ－１／ＹＨ－２计算机上将多重散射Ｘα自洽场方法（ＳＣＦ－Ｘα－ＳＷ）程序和线性Ｍｕｆｆｉｎ－ｔｉｎ轨道方法（ＬＭＴＯ）程序做了改进，实现了向量化和并行化。研究了Ｃ６０的能级；计算了苯分子从１ｅ１ｇ，２ｅ２ｇ和１ａ２ｕ开始激发的１０８个Ｒｙｄｂｅｒｇ态单电子轨道激发能，即１ｅ１ｇ，２ｅ２ｇ，１ａ２ｕ→ｋａ１ｇ（ｋ＝３－１１），ｋｅ２ｇ（ｋ＝２－７），ｋｅ１ｕ（ｋ＝３－８），ｋｅ１ｇ（ｋ＝３－５     

O（^1D）＋H2非绝热碰撞动力学的Ehrenfest模型研究

本采用Ｈ２Ｏ的二个＾１Ａ１态的双值多体项展式（ＤＭＢＥ）势能函数，用Ｅｈｒｅｎｆｅｓｔ模型方法研究了反应（１）Ｏ（＾１Ｄ）＋Ｈ２→ＯＨ和（２）Ｏ（＾１Ｄ）＋Ｈ２→ＯＨ（Ａ＾２∑＾＋）＋Ｈ的非绝热碰撞动力学过程。讨论了电子非绝热跃迁对反应（１）的影响及Ｈ２振动能对反应（２）的促进作用。并求得反应（１）的室温速度常数为０．９４４×１０＾－＾１＾０ｃｍ＾３．ｍｏｌｅｃｕｌｅ＾－＾１．ｓ＾－＾１。     

超声射流冷却SO2^—A2—^1A1激光诱导荧光激发谱

测得了３１５￣３３０ｎｍ超声射流冷却下ＳＯ２＾１Ａ２－＾１Ａ１激光诱导荧光（ＬＩＦ）激发谱，获得了７个有明显Ｋ结构的Ｃ型跃迁的转动子带分辨谱，并将７０个转动子带归属为（１，ｍ，１）－（０，０，０）和（０，ｎ，１）－（０，０，０）（４≤ｍ≤７，８≤ｎ≤１０）的跃迁带系。光谱分析得到ＳＯ２＾１Ａ２－＾１Ａ１跃迁的带源ｖ００、＾１Ａ２态弯曲振动频率ｖ′２，非谐性常数Ｘ２２′分别为（２７９５０±５）、（２     

类氦离子1,3P激发态Schrodinger方程的直接解

利用相关函数（ＣＦ）－超球谐（ＨＨ）－广义Ｌａｇｕｅｒｒｅ（ＧＬＦ）方法直接求解类氦离子ｎ＾１,３Ｐ（ｎ＝１,２,３）低躺激发态的Ｓｃｈｒ¨／ｏｄｉｎｇｅｒ方程,得氦原子的本征能量分别为－２．１３３１７Ｅｈ（１＾３Ｐ）,－２．１２３８３Ｅｈ（１＾１Ｐ）,－２．０５８１０Ｅｈ（２＾３Ｐ）,－２．０５５１６Ｅｈ（２＾１Ｐ）,－２．０３２３５Ｅｈ（３＾３Ｐ）和－２．０３１０９Ｅｈ（３＾１Ｐ）,它们与文献     

用速度成像方法测量碘原子的光电子能谱及角分布

使用离子速度成像（Ｉｏｎ Ｉｍａｇｉｎｇ－Ｖｅｌｏｃｉｔｙ Ｍａｐｐｉｎｇ）技术来测量光电子能谱及其角分布，对碘原子在２７７ｎｍ附近的（２＋１）多光子电离过程Ｉ＾＊（＾２Ｐ１／２）→Ｉ′（＾１Ｄ２）６ｐ［１］１／２→Ｉ＾＋和Ｉ（２Ｐ３／２）→Ｉ′（＾３Ｐ０）６ｐ［１］１／２→Ｉ＾＋进行了研究。与文献报道的结果相比，分辨率要好５倍，相对能量分辨率达到６％。还讨论了速度成像方法中速度分布校正和重构三维     

低温下C60拉曼谱线的强度变化

测量了２８４－１０Ｋ范围内Ｃ６０的拉曼谱，作了了拉曼谱线的强度－温度曲线。这些曲线都在一级相变点２５０Ｋ附近呈现突变：Ａｇ模谱线的强度及其变化都显著大于Ｈｇ的：１４７０，４９８ｃｍ＾－１二者的曲线起伏趋势完全相反。     

High-frequency driven capillary flows speed up the gas-liquid phase transition in zero-gravity conditions

Under weightlessness conditions, the phase transition of fluids is driven only by slow capillary flows. We investigate the effect of high-frequency vibrations to reproduce some features of gravity effects and show that such vibrations can greatly modify the phase transition kinetics. The investigation is performed in H2 near its critical point (critical temperature 33 K) where critical slowing down enables the phase transition process to be carefully studied. Gravity effects are compensated in a strong magnetic field gradient.     

Low-energy electron diffraction study of the phase transition of Si(001) surface below 40 K

The phase transition of Si(001) surface below 40 K was studied by low-energy electron diffraction (LEED). The temperature dependence of the intensities and widths of the quarter order diffraction spots and LEED intensity versus electron energy curves (I-V curves) were obtained in the temperature region from 20 to 300 K. While the spot intensities of the quarter order spots decrease and the widths broaden, the I-V curves do not change so much below 40 K. This clearly shows that a phase transition occurs from an ordered phase above 40 K to a disordered phase below 40 K.     

Lattice dynamics,ferroelectricity and raman spectrum of BaTiQ3 in cubic phase

A dynamical model involving non linear anisotropic polarisability of oxygen is used to calculate the phonon dispersion curves and the Raman spectrum of barium titanate at 421 K near the paraelectric-ferroelectric phase transition. The temperature phase dependence of the dispersion curves is studied and the ferroelectric soft mode is described.     

Temperature-dependent surface X-ray diffraction on K/Ag(001)-(2 × 1)

Temperature-dependent surface X-ray diffraction experiments have been performed on the K/Ag(001)-(2 × 1) adsorption system. The structure is characterized by a missing-row geometry in which alternate Ag rows along [1 0] are missing. The K atoms reside within the large grooves coordinated by six Ag atoms at a distance of 3.44(5) Å, corresponding to an effective K-radius of 2.00(5) Å. Large anisotropic disorder is observed for both the K-atoms and the top-layer (“ridge”) Ag atoms. The K-atom displacements are largest in the direction along the grooves, whereas for the Ag atoms the vibrations along [110] are significantly larger. The temperature dependence of the Ag vibrations is in accordance with Debye theory for the [110] direction, but deviates from it for the [1 0] vibrations at high temperature. In contrast to the K-atoms, the out-of-plane vibrations of the top-layer Ag atoms are larger than the in-plane vibrations. The inclusion of anharmonic contributions to describe the Ag disorder significantly improves the fits. It is shown that if anharmonicity is neglected the interlayer contraction is overestimated (Δd₁₂/d₁₂ only −3.2%, instead of −12.7% if anharmonicity is neglected). Due to the anharmonicity, different definitions of the atomic position arise (mean, mode and equilibrium position), which are discussed on the basis of the results.     

Lattice dynamics and the phase transition from the cubic phase to the tetragonal phase in the LaMnO<Subscript>3</Subscript> crystal within the polarizable-ion model

The paper reports on the results of ab initio calculations of the static and dynamic properties of the LaMnO₃ crystal with a perovskite structure in the cubic, rhombohedral, and orthorhombic phases. The calculations are performed within the ionic crystal model, which takes into account the deformability and polarizability of the ions. It is revealed that the spectrum of lattice vibrations in the cubic phase contains unstable vibrational modes, which occupy the phase space in the entire Brillouin zone. The eigenvectors of the softest mode at the boundary point R of the Brillouin zone are associated with the displacements of the oxygen ions and correspond to the “rotation” of the MnO₆ octahedron. The condensation of one, two, and three components of this mode leads to the tetragonal, orthorhombic, and rhombohedral distortions of the structure. The structural phase transition is described in terms of the local mode approximation with the use of the double perovskite unit cell, in which the MnO₆ octahedron is explicitly separated. The parameters of the model Hamiltonian are determined. The static properties are investigated by the Monte Carlo method. The calculated temperature of the phase transition from the cubic phase (9800 K) is considerably higher than the melting temperature of the crystal under investigation. The calculated frequencies of long-wavelength lattice vibrations in the experimentally observed orthorhombic and rhombohedral phases are in reasonable agreement with experimental data.     

Absorption spectra of ZnO:Li thin films in the region of a phase transition

We have studied the temperature variation of the intrinsic absorption edge for ZnO:Li films obtained by high-frequency magnetron sputtering. We have observed anomalous behavior of the optical bandgap width in the vicinity of the temperature of a ferroelectric phase transition at T = 327 K. For the first time, we have observed the appearance of this phase transition on the thermally stimulated depolarization (TSD) current curves.     

Optical investigations of the metal-insulator transition in a low-dimensional organic conductor (EDT-TTF)4[Hg3I8]

The polarized reflectance spectra of single crystals of the low-dimensional organic conductor (EDT-TTF)₄[Hg₃I₈] undergoing a metal-insulator phase transition at a temperature T < 35 K have been presented. The spectral region of the study is 700–6000 cm^?1 (0.087–0.74 eV), and the temperature range is 300–9 K. It has been shown that the reflectance spectra are determined by a system of quasi-free electrons of the upper half-occupied molecular π-orbitals, which form a half-filled metallic band in the crystals. A high anisotropy of the spectra and their temperature dependences have been found. For two polarizations, the quantitative analysis of the spectra at 100 and 25 K has been performed in the framework of the phenomenological Drude model, the effective mass and the width of the initial metallic π-electron band have been deter-mined, and it has been found that the conducting system in the crystals has a quasi-one-dimensional character. As temperature decreases, the spectra demonstrate substantial changes indicating the formation of the energy gap (or pseudogap) in the spectrum of electronic states in the range of ～1500–2500 cm^?1. In the low-frequency region (700–1600 cm^?1), a vibrational structure has been observed, and the most intense feature of the structure (ω = 1340 cm^?1) is caused by the interaction of electrons with intramolecular vibrations of the C=C bonds of the EDT-TTF molecule. For temperatures of 15 and 9 K, the analysis of the spectra has been performed in the framework of the theoretical “phase phonon” model taking into account the interaction of electrons with the intramolecular vibrations. It has been concluded that the metal-insulator transition observed in the reflectance spectra of the crystals is similar to the Peierls dielectric transition that occurs in a system of electrons coupled with the intramolecular vibrations of the molecules forming the crystal.     

Raman scattering in sodium nitrite crystals near the phase transition

Optical Raman spectra of a ferroelectric sodium nitrite crystal have been detected in a wide spectrum range at various temperatures, including the region of the ferroelectric phase transition. A manifestation of a transverse soft polar mode of the A ₁(z) type responsible for the ferroelectric phase transition has been discovered in the spectrum at room temperature. This mode has been found to become overdamped even far from the ferroelectric phase transition temperature. This mode also appears as a central peak under heating. It has been found that the pseudoscalar mode of the A ₂ type has the highest intensity in the Raman spectrum of sodium nitrite. The frequency corresponding to the maximum intensity of this mode in the Raman spectrum varies from 130 cm^–1 at 123 K to 106 cm^–1 at T = 513 K. A fair agreement of the experimental data for the A ₁(z) mode with the Lyddane–Sachs–Teller relation has been established. The polariton curves for the A ₁(z) polar mode and the dispersion curves for axinons has been plotted.     

Lattice vibrational study of the phase transition in the plastic crystal adamantane (C10H16)

Using the Raman technique we have studied the lattice vibrations of the prototype plastic crystal adamantane (C₁₀H₁₆). The measurements, as a function of temperature through the phase transition (208K), show splittings in certain lines. At room temperature using hydrostatic pressure, we also induced a phase transition. The transition is detected by Raman measurements, and we observe splittings of the very same vibrational lines. This indicates that the pressure induced phase transition yields the same crystal structure as the low temperature structure. Some analysis of the pressure and temperature derivatives of the vibrational modes is presented.