水分子F态超快动力学：时间分辨光电子能谱研究

本文利用双光子激发和时间分辨的光电子成像技术研究了水分子■态的超快动力学.这是首次对水分子■态进行时间分辨的实验研究.水(重水)分子■和■态的寿命分别为1.0±0.3(1.9±0.4)和10±3(30±10)皮秒.我们提出■态主要通过非绝热耦合内转换到■态,而■态通过科里奥利相互作用耦合到■态.     

Millimeter-Wave Spectroscopy of HCCCP in Excited Vibrational States

The rotational spectra of the unstable HCCCP molecule have been investigated in the millimeter-wave region for the main excited vibrational states which lie below 1000 cm(-1), namely nu(4) (C&bond;C stretch), nu(5) (HCC bend), nu(6) (CCC bend), nu(7) (CCP bend), 2nu(6), 2nu(7), 3nu(7), 4nu(7), nu(5) + nu(7), and nu(6) + nu(7). l-type resonance effects have been taken into account in the analysis of the spectra, so that the values of the anharmonicity constants x(L(66)), x(L(77)), x(L(57)), and x(L(67)) could be determined. The anharmonic interactions which couple the nu(4) state with nu(6) + nu(7), 2nu(6), and 4nu(7) have been also considered, yielding the unperturbed value of the alpha(4) vibration-rotation coupling constant. Copyright 2001 Academic Press.     

Millimeter-Wave Spectroscopy of PO in Excited Vibrational States up to v=7

We have measured millimeter-wave transitions of PO, produced by the chemiluminescent reaction of oxygen with white phosphorus, P₄, in excited vibrational states up to v=7. We were hence able to obtain more precise rotational, spin-rotation, Λ-doubling, and hyperfine constants for this radical and better describe their vibrational dependence. The equilibrium PO bond length was determined as r_e=1.476 373 55(10) Å.     

通过飞秒泵浦探测技术研究PbS纳米颗粒的激发态瞬态动力学过程

利用飞秒泵浦探测技术研究了PbS半导体纳米颗粒复合的SiO₂溶胶凝胶薄膜的瞬态动力学过程。通过改变激发探测波长和激发光强度,研究引起PbS半导体纳米颗粒的非线性吸收的两种机制。当激发探测波长选在激子吸收峰附近(620nm)时,由于激子的饱和吸收引起的光致漂白,当激发波长选在激子能态的低能侧(753,800nm),同时观察到激子的饱和吸收和双激子效应引起的光致吸收。研究了激子的饱和吸收和双激子效应引起的激发态吸收随激发态电子-空穴对浓度的变化关系,表明双激子效应与载流子浓度有很大关系。在高激发强度下,双激子效应引起的诱导吸收远远大于激子跃迁引起的光致漂白,双激子效应在非线性吸收中起着决定性作用。     

Sc原子高激发态理论研究

利用相对论性多通道量子亏损理论计算了Sc的原子里德堡态能级 .计算结果显示 ,由于通道间的相互作用 ,使得光谱非常复杂 ,这与实验测量结果是一致的. The energy levels of Rydberg series of Sc atom have been calculated by Relativistic Multichannel Theory (RMCT). The calculations reveal that the Rydberg spectra are complex due to the channel interactions, which is consistent with the experimental spectra.     

Vibrational Population of Hydrogen Molecules Excited by an RF Discharge in an Expanding Thermal Arc Plasma as Determined by Emission Spectroscopy

This work is devoted to the determination of the vibrational population of hydrogen molecules in the ground and excited electronic states from the analysis of visible spectra of the H₂ molecules excited by an RF discharge in an expanding thermal arc plasma. Comparison of the experimental results on relative electron-impact excitation cross sections for the transition H₂(X¹Σ, υ⁰ = 0)→ H₂(d³II_u, υ′) with other experiments, and with calculations based on the Franck-Condon principle, shows good agreement. This means, that for plasma under investigation: 1) in the ground electronic state H₂(d³II_u,υ′), only the lowest vibrational level with υ⁰ = 0 is significantly populated, and 2) direct electron exictation of H₂(d³II_u, υ′, υ′) state from the ground state H₂(X¹Σ, υ⁰ = 0) dominates.     

Torsional Splittings in Small-Amplitude Vibrational Fundamental States of Methanol-Type Molecules

Group-theoretical methods are used to show that inverted torsional splittings in fundamental levels of small-amplitude vibrations of methanol-like molecules can be parameterized and understood in terms of the energy level patterns induced when a pair of high-barrier torsionally split components of given v(t) and (t)A+(t)E symmetry species in the molecular symmetry group G(6) is allowed to interact with small-amplitude vibrational modes of symmetry (v)E. Such doubly degenerate (v)E vibrational modes arise rather naturally in G(6) (isomorphic with the point-group C(3v)) for those methyl-group vibrations in point-group-C(s) asymmetric tops such as CH(3)-CHO that are analogs of the degenerate methyl-group stretch, bend, and rocking vibrations in point-group-C(3v) symmetric tops such as CH(3)-C identical withC-H. The present group-theoretical treatment is somewhat different from, but (as a comparison of model parameters shows) still fundamentally similar to, the recent local mode explanation of inverted torsional splittings in the C-H stretching fundamental region in methanol. Copyright 2001 Academic Press.     

141Nd激发态的在束γ谱学研究

通过130Te(16O,5nγ)141Nd反应布居了141Nd的高自旋态能级. 对反应产生的在束γ射线进行了γ射线单谱和γ-γ符合测量. 建立了激发能达7614.5keV的141Nd能级纲图,新发现了12条γ射线和15个能级. 基于实验测量的γ跃迁各向异性,建议了141Nd部分能级的自旋值. 用一个h11/2价中子空穴与142Nd核芯晕态的耦合可以定性地解释141Nd的能级结构.     

Intermolecular Vibrational Relaxation in Mixtures of Excited Benzophenone and Anthraquinone Molecules with Water Vapor

The intermolecular vibrational energy transfer from triplet molecules of benzophenone and anthraquinone to H₂O molecules has been investigated. To determine the rates of establishment of vibrational (V-V) and thermal (V-T) equilibrium in a vibrational quasi-continuum of mixed singlet-triplet levels, the dependences of the decay rates and intensities of the fast and slow components of delayed fluorescence on the H₂O vapor pressure have been investigated. For V-V relaxation, the efficiencies ₁ and the mean energies E transferred per collision in mixtures with H₂O and other polyatomic foreign gases have been compared. It has been established that the efficiencies ₁ for quasi-resonant vibrational energy transfer (V-V) from benzophenone and anthraquinone to H₂O are an order of magnitude lower than the gas-kinetic ones and lower than those obtained under the same experimental conditions for such foreign gases as C₅H₁₂, SF₆, and CCl₄, and decrease with increasing temperature in the 433–513 K range. It has been concluded that the mechanism of V-V relaxation in mixtures with H₂O are determined by long-range attractive forces. In mixtures with H₂O, no acceleration of V-T relaxation due to the formation of hydrogen bonds has been revealed. The low-efficiency thermalization process (V-T relaxation) is controlled by short-range repulsive forces, and the differences between the intensities ₂ for mixtures of benzophenone and anthraquinone with H₂O and other polyatomic gases are determined by the change in the reduced mass of interacting molecules.     

A High Resolution Study of the Shock Excited Spectrum of Yttrium Oxide

Abstract

The blue-green (B²? X²?) and orange (A²? –X²?) systems of yttrium oxide have been shock excited at temperatures of about 4000°K and photographed at high dispersion (～ 1.2Å/mm) in the first order of a 21 ft. grating spectrograph. The high dispersion shock excited spectra were recorded using multiple exposures and latensification of extremely high speed film. Over 50 new bands have been observed and assigned to specific vibrational transitions for the systems. New molecular constants have been derived from the A, B and X states. Provisional calculations have been made of Franck-Condon factors and r-centroids for the systems appropriate to new constants.     

Vibrational Spectroscopy of CH/CD Stretches in Propadiene: An Algebraic Approach

Using Hamiltonian based on Lie algebraic method, the stretching vibrational modes of C3H4 and C3D4 molecules are calculated up to higher overtones. The model appears to describe C-H and C-D stretching modes with less number of parameters. The locality parameter ξ confirms the highly local behaviour of the stretching modes of these molecules.     

Nature of the Electron Excited States and Energy Transfer in Bichromophore Coumarin Molecules

Results of experimental and theoretical research for three bichromophore molecules, trans-stilbene-CH₂-coumarin 120 (I), 4-methylumbelliferone-CH₂-UC 17, and 4-(3-fluoro)-methylumbelliferone-CH₂-UC 17 (II, III), are presented. Schemes of photophysical processes in the bichromophore molecules based on quantum chemical calculations by the INDO method and theory of radiationless transitions in polyatomic organic molecules are suggested. After optical excitation to the strong donor absorption band, the fast internal conversion processes develop there. As a result, the molecule is found in the S ₁ ^* -state localized on the acceptor moiety. It is shown that a mechanism of intramolecular transfer energy in bichromophores different from that proposed by Förster may be realized. Excitation energy, initially located on D, will be transferred from the donor moiety to the acceptor chromophore in convenience of the internal conversion process. The intramolecular electronic energy transfer from energy donor to energy acceptor may be interpreted as the internal conversion process. The rate constants of internal conversion are calculated.     

Double-Modulation Submillimeter-Wave Spectroscopy of HOC(+) in the nu(2) Excited Vibrational State

The submillimeter-wave rotational transitions of HOC(+) in the nu(2) excited state are first detected using the double-modulation method, and the precise transition frequencies and the much improved molecular constants are obtained. The measurements of the ground state HOC(+) and DOC(+) submillimeter-wave lines are extended up to the 840-GHz region. It is found that the higher order centrifugal distortion constant, H, is necessary to fit the observed transition frequencies to the experimental accuracy. Copyright 2000 Academic Press.     

Br2分子里德堡态的高分辨转动谱研究

用窄线宽（０．０８ｃｍ＾－＾１）脉冲可调谐紫外激光和（２＋１）多光子电离方法测量了Ｂｒ２的里德堡（Ｒｙｄｂｅｒｇ）态光谱,在７００００－７１５００ｃｍ＾－＾１范围内,获得了溴分子［П３／２］４ｄ振动系列,测量（ｖ＇,ｖ”）＝（１,０）,（２,０）的高分辨振转谱,得到其转动常数Ｂ’７９－８１分别为０．０８８３２和０．０８８０５ｃｍ＾－＾１,并提出此系列的角动量量子数Ω应为１。     

Control of Spinning Sidebands in High Resolution NMR Spectroscopy

The presence of spinning sidebands can severely compromise the detection of low molarity analytes. Spinning sidebands have traditionally been minimized by improving the magnetic field homogeneity and by varying the spinning of the sample in a linear fashion during data acquisition. The effect of the latter is to spread the spinning sideband intensity over a range of frequencies so that the final result is a spinning sideband whose shape reflects the distribution of spinning speeds. We have designed a customized profile of spinner speed variation that optimizes the reduction of spinning sidebands. The customized profile is based on theoretical considerations of how the intensity of sidebands vary with the rate of sample rotation and also compensates for the mechanical design of the spinner mechanism. The result is a unique combination of an exponential increase in gas flow rate to balance the theoretical considerations coupled with a strategically placed rapid change in air flow to annul the sluggish response of the spinning mechanism to acceleration. The resulting sideband shape is a broad, flat, square step in the baseline that is least likely to interfere with low molarity analyte peaks.     

176，178Os新低位激发态的识别

利用在束实验产生具有β^＋/EC衰变性质核素^176，178Ir，分析了在柬实验条件下获得的γ—γ符合数据，识别出了^176Os的4条新能级和13条新γ跃迁、^178Os的5条新能级和14条新γ跃迁。籍助氨喷嘴快速带传输系统，进一步对^176Ir的β’/EC衰变进行了测量，在确认在束测量新γ射线的同时建议了^176Ir的一个低自旋同核异能态。通过两准粒子耦舍的半经验计算，建议了^176，178Ir基态及同核异能态的组态。The γ rays following the β^＋/EC decay of ^176. 178Ir nuclei have been investigated using in-beam γ- ray experiment. A total of 4 new levels, 13 new γ transitions of ^176Os and 5 new levels, 14 new γ transitions of ^178Os were identified. In addition, with the aid of a helium-jet recoil fast tape transport system, the β^＋/EC decay of ^176Ir was further studied, the above new γ rays were proved and an isomer was proposed in ^176Ir. By the semiempirical calculations of two-quasiparticle intrinsic states of odd-odd nuclei, the configurations of ground states and isomeric states were also proposed for ^176, 178Ir     

Erratum: Photodissociation Efficiency Spectroscopy Study of the Rydberg Excited Ion-Pair States of Carbon Dioxide

In our paper published on Chinese Physics Letters 26（2009）103401, there were some mistakes in Table 1. Here is the corrected table：