CO分子四个电子态的振转谱:两种效应修正方法的比较

基于完全活性空间自洽场方法和多参考组态相互作用(multi-reference configuration interaction method,MRCI)方法,采用MRCI+Q/CBS(TQ5)+CV+SR (方法 A)和aug-cc-pwCVn Z-DK (n=T, Q, 5)(方法 B)方案,分别计算了包含Davidson修正(+Q)、芯-价电子关联(core-valence correlation correction, CV)效应以及标量相对论(scalar relativistic, SR)效应的CO分子的基态X^1Σ^+和激发态a^3Π, a^(′3)Σ^+和A^1Π的势能曲线.在此基础上,获得了这些电子态的振-转谱.通过与实验结果比较发现:方法 A适合a^(′3)Σ^+和A^1Π等较高激发态的振-转谱的计算,方法 B更适合基态X^1Σ^+和第一激发态a^3Π的振-转谱的精细计算.该研究可以为其他小分子高精度振-转谱快速计算方案选择提供参考.

动力学群方法计算分子的振－转能谱

用动力学群方法计算了三原子分子Ｎ２Ｏ的部分振－转能谱，结果与实验值符合较好．

Three-Dimensional Ab Initio Potential Energy Surface and Predicted Spectra for the CH_(4)-Ne Complex

We present a new three-dimensional potential energy surface(PES)for CH_(4)-Ne complex.The electronic structure computations were carried out using the coupled-cluster method with singles,doubles,and perturbative triples[CCSD(T)],the augmented correlationconsistent aug-cc-pVXZ(X=T,Q)basis sets were employed with bond functions placed at the mid-point on the intermolecular axis,and the energies obtained were then extrapolated to the complete basis set limit.Analytic intermolecular PES is obtained by least-squares fitting to the Morse/Long-Range(MLR)potential function form.These fits to 664 points have root-mean-square deviations of 0.042 cm^(−1).The bound rovibrational levels are calculated for the first time,and the predicted infrared spectra are in good agreement with the experimental values.The microwave spectra for CH_(4)-Ne dimer have also been predicted for the first time.The analytic PES can be used for modeling the dynamical behavior in CH_(4)-(Ne)N clusters,and it will be useful for future studies of the collision-induced-absorption for the CH_(4)-Ne dimer.

Direct Observation of Electron-Vibration Coupling at MXene-Solvent Interface

MXenes,a new family of two-dimensional(2D)materials,have received extensive interest due to their fascinating physicochemical properties,such as outstandinglight-to-heat conversion efficiency.However,the photothermal conversion mechanism of MXenes is still poorly understood.Here,by using femtosecond visible and mid-infrared transient absorption spectroscopy,the electronic energy dissipation dynamics of MXene(Ti_(3)C_(2)T_(x))nanosheets dispersed in various solvents are carefully studied.Our results indicate that the lifetime of photoexcited MXene is strongly dependent on the surrounding environment.Especially,the interfacial electron-vibration coupling between the MXene nanosheets and the adjacent solvent molecules is directly observed following the ultrafast photoexcitation of MXene.It suggests that the interfacial interactions at the MXene-solvent interface play a critical role in the ultrafast energy transport dynamics of MXene,which offers a potentially feasible route for tailoring the light conversion properties of 2D systems.

Energy Transfer among Modes in a Non-Slender Elastic Beam Subject to Vortex-Induced Vibration

The vibration of an elastic beam experiencing vortex-induced vibration is numerically analyzed employing a wake-oscillator model. The influence of the excited mode, the initial velocity, the shedding pulsation and the mass ratio on the energy transfer among modes and the vibration amplitude is determined. Multiple frequencies are detected, and the power spectral density of the beam tip time series is used to calculate the dominant frequency.

High Precision Cavity Ring Down Spectroscopy of 6υ3 Overtone Band of 14N2 16O near 775 nm

Transitions of the 6υ3 overtone band of ^14N2 ^16O near 775 nm have been studied by continuous-wave cavity ring-down spectroscopy. Line positions and intensities were derived from a fit of the line shape using a hard-collisional profile. The line positions determined with absolute accuracy of 5×10^-4 cm^-1 allowed us to reveal finer ro-vibrational couplings taking place after J〉14 except a strong anharmonic interaction identified by the effective Hamiltonian model. The absolute line intensities have also been retrieved with an estimated accuracy of 2% for a majority of the unblended lines. A new set of ro-vibrational and dipole moment parameters were derived from the experimental values. A comparison between the line positions and intensities of the 6υ3 band obtained in this work and those from previous studies is given.

Computer Assisted Assignments of Rotationally Resolved Molecular Spectra

A graphically oriented interactive program for assignments of rotationally resolved molecular spectra has been devised. The program functions by grouping spectral lines in term of the second difference principle. and graphing spectral intensity versus frequency in a bar graph of the selected groups, distinguished by color and/or line-type. This allows for easy detection of regular patterns buried in the observed spectrum. Furthermore, it includes a Loomis-Wood view for assisting in spectral assignments. As an example, the program was applied in assigning the molecular spectrum of the production in the discharge of PCl3 buffered by helium gas, which may belong to several species. The results suggest that the program is highly efficient and quite useful in the assignment and the analysis of molecular spectra, especially those of symmetric top, slightly asymmetric top and linear molecules. The accuracy and efficiency of this program will likely ensure its wide application in the processing of molecular spectra.

Preliminary study in vitro brain tumor with high resolution magic angle spinning proton magnetic resonance spectroscopy

Objective： To explore water soluble metabolite features of brain tumor specimens with HRMAS-^1HMRS and its potential clinical value. Methods： There were thirty cases of pathologically proven brain tumor, including 6 Ⅰ-Ⅱ grade astrocytomas, 7 Ⅲ grade anaplastic astrocytomas, 10 IV grade glioblastomas and 7 meningiomas. Used Varian Company 600 MHz spectrometer with the Nano-probe for acquisition HRMASJHMRS, which was postprocessed with jMRUI 3.2 version software. These metabolic probability and their ratios to Cr were summed. Results： （1） HRMAS-^1HMRS could resolve NAA, PCr/Cr, GPC ± PCho ± Cho, Glu/GIn, Gly, Tau, Ala, Lac, ml and so on. All samples showed Lac, 6 samples showed unknown single peak at 3.72 ppm or 3.90 ppm. （2） The mean Cho/Cr of 6 Ⅰ-ⅡI grade astrocytomas was 2.42 ± 1.01 （P = 0.003, compared with glioblastoma）. The mean Cho/Cr of 7 anaplastic astrocytomas was 3.48 ± 0.59 （P = 0.01, compared with glioblastoma）. The Cho/Cr of 10 glioblastomas broadly ranged from 0.9 to 11.3 （mean 5.40 ± 1.23）. From Ⅰ-Ⅱ grade astrocytoma to glioblastoma, Ala/Cr, Tau/Cr and Gly/Cr trends were increased; the mean Ala/Cr of glioma was 0.31 ± 0.13. （3） Meningiomas showed higher Ala and Cho. Their Cr was lower than that of gliomas. 4/7 cases had no NAA, 3/7 patients had lower NAA. Mean Cho/Cr was 3.56 ± 1.01, Ala/Cr was 0.53 ±0.28 （P = 0.006, compared with glioma）. Conclusion： HRMAS-^1HMRS can show further details in vivo MRS, resolve in vivo spectroscopic metabolite of Cho compound and differentiate the extent of benign and malignant glioma. With the increase in the malignant degree of gliomas, Cho, ml, Ala, Tau and Gly will increase. HRMAS-^1HMRS is the only method of isotropic spectroscopy for pathological specimens.

Theoretical Studies of Electron Paramagnetic Resonance Parameters for Cr^4＋ Ions in Ca2GeO4 Crystals

The electron paramagnetic resonance (EPR) parameters (zero-Geld splitting Dand g factors g_‖, g_⊥) of Cr~(4+) ions in Ca_2 GeO_4 crystals have been calculated from thecomplete high-order perturbation formulas of EPR parameters for a 3d~2 ion in trigonal MX_4clusters. In these formulas, in addition to the contributions to EPR parameters from the widely usedcrystal-field (CF) mechanism, the contributions from the charge-transfer (CT) mechanism (which areoften neglected) are included. From the calculations, it is found that for the high valence state3d~n ions in crystals, the reasonable explanation of EPR parameters (in particular, the g factors)should take both the CF and CT mechanisms into account.

INDIRECT DETERMINATION METHOD OF DYNAMIC FORCE BY USING CEPSTRUM ANALYSIS

The dynamic load spectrum is one of the most important basis of design and dynamic characteristics analysis of machines. But it is difficult to measure it on many occasions, especially for mining machines, due to their bad working circumstances and high cost of measurements. For such situation, the load spectrum has to be obtained by indirect determination methods. A new method to identify the load spectrum, cepstrum analysis method, was presented in this paper. This method can be used to eliminate the filtering influence of transfer function to the response signals so that the load spectrum can be determined indirectly. The experimental and engineering actual examples indicates that this method has the advantages that the calculation is simple and the measurement is easy.

Electron transfer photochromism of Ln-based(Ln=Dy,Tb)coordinated behavior

Switching on/off single-molecule magnets(SMMs)at room temperature is still a challenge in moleculebased magnets.Herein,two photochromic Ln-based(Ln=Dy,Tb)phosphonate coordinated polymers were synthesized with regulable SMM behavior.The reversible room-temperature photo-coloration was an electron transfer process with a generation of relatively stable radicals,characterized by structural analyses,ultraviolet-visible,luminescence and electron spin resonance spectra and magnetic measurements.Importantly,owing to the antiferromagnetic coupling interactions between Ln^(3+) ions and photogenerated radicals,the room-temperature light irradiation surprisingly switched off the SMM behavior,showing the first example of radicalquenched SMMs in the molecule-based magnets.Moreover,the silient SMM behavior could be recovered after eliminating photogenerated radicals via heat treatment,showing a reversible off/on switch of SMMs via light and heat.This work constructs a system for switching off/on SMMs through electron transfer photochromism,providing a visual operation way via naked-eye-detectable coloration for the switchable SMMs.

Polarized upconversion luminescence from a single LiLuF_(4):Yb^(3+)/Er^(3+) microcrystal for orientation tracking

Polarized upconversion luminescence(UCL)of lanthanide-doped micro/nano-crystals has shown great promise in single-particle tracking and super-resolution bioimaging.However,because of the spectral line broadening and multiple sites of lanthanide in upconversion particles(UCPs),the crystal-field(CF)polarization components of UCL are usually undistinguishable.Herein,we report the linearly polarized UCL in LiLuF_(4):Yb^(3+)/Er^(3+) single microcrystals with resolvable CF transition lines and a polarization degree up to 0.82.The CF levels and CF transition lines of Er^(3+),as well as their emission polarization anisotropy,are unraveled for the first time through low-temperature and high-resolution photoluminescence(PL)and UCL spectroscopies.By taking advantage of the well-resolved and highly-polarized CF transition lines of Er^(3+),we demonstrate the application of LiLuF_(4):Yb^(3+)/Er^(3+) single microcrystals as anisotropic UCL probes for orientation tracking.These findings provide fundamental insights into the polarization anisotropy of UCL in lanthanide-doped single particles,thus laying a foundation for the future design of anisotropic luminescent probes towards versatile applications.