Analyzing ultrafast multiplex coherent anti‐Stokes Raman spectra with picosecond probing

This article reports an efficient method to simulate time and frequency resolved coherent anti‐Stokes Raman scattering spectra measured with picosecond pump and probe fields and ultrashort Stokes pulses. A systematic comparison of measured and simulated time and frequency dependent data is presented for carbon tetrachloride, chloroform, cyclohexane, octane, and poly(methyl methacrylate). While the first compound exhibits no Raman active modes in the considered spectral region of the CH‐stretch vibrations, the other ones show Raman spectra of increasing complexity. Vibrational frequencies and homogeneous dephasing rates are extracted by fitting explicit analytical formulas to the recorded data. Interference between nonresonant and resonant contributions to the nonlinear polarization is taken fully into account. The ability to measure the influence of inhomogeneous broadening is discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Fermionic stochastic differential equations and the index of Fredholm operators

The index of a Fredholm operator associated to a-summable Fredholm module is expressed in terms of the vacuum expectation value of a unitary operator-valued stochastic process which satisfies a stochastic differential equation with unbounded coefficients driven by fermion noise.     

Distance distributions and dynamics of a zinc finger peptide from fluorescence resonance energy transfer measurements

Time-resolved fluorescence resonance energy transfer (FRET) measurements were used to measure distance distributions and intramolecular dynamics (site-to-site diffusion) of a 28-residue single-domain zinc finger peptide in the absence and presence of zinc ion. Energy transfer was measured between TRP₁₄ and a N-terminal DNS group. As expected, the TRP-to-DNS distance distribution for zinc-bound peptide is shorter and narrower (R _av=11.2 Å,hw=2.8 Å) than the metal-free peptide (R _av=20.1 Å,hw=14.5 Å). The degree of mutual donor-to-acceptor diffusion (D) was also determined for these distributions. For zinc-bound peptide there is no detectible diffusion (D0.2 Ų/ns), whereas for metal-free peptide a considerable amount of motion is occurring between the donor and the acceptor (D=12 Ų/ns). These results indicate that the zinc-bound peptide folds into a unique, well-defined conformation, whereas the metal-free conformation is flexible and rapidly changing. The absence of detectible mutual site-to-site diffusion between the donor and the acceptor in the metal-bound zinc finger peptide indicates that intramolecular motion is essentially frozen out, on the FRET time scale, as a consequence of zinc coordination.Dedicated to the memory of Barbara D. Wells.     

Investigation of the dissociative adsorption for cyclopropane on the copper surface by density functional theory and quantum chemical molecular dynamics method

The dissociative adsorption of cyclopropane on the copper surface was studied using quantum chemical molecular dynamics method with “Colors-Excite” code and density functional theory by Amsterdam Density Functional program (ADF2000). The excited state of cyclopropane was used as adsorbate to simulate the dissociated adsorption under an irradiation energy of ca. 10 eV. One of the C-C bonds in cyclopropane was broken and the two new bonds between cyclopropane and copper surface were formed. The electrons transferred from the copper atoms to cyclopropane with a value of about 0.2e. The shorter distances between the carbons and surface copper atoms showed the existence of strong interaction. Consistently, the results indicated metallacyclopentane was the most possible intermediate species in dissociative adsorption by ADF2000 and “Colors-Excite” method.     

Survivor statistics and damage spreading on social network with power-law degree distributions

Damage spreading(DS) of the random graph networks with power-law degree distributions is investigated using Glauber dynamics. Various subgraphs defined by the probability of acquaintance show distinct features in DS as measured by Hamming distance. A heuristic understanding of the long-time value of damage is achieved through an analysis of the survivor statistics. All survivors are dynamical, flipping in unison for the controlled sample and the damaged sample. Verification of these dynamic survivors is achieved through the introduction of a new measure of self-damage.     

Traffic dispersion induced by noise in off-lattice model

We study the dispersion of vehicles induced by speed fluctuation on a single-lane highway under open boundary. We extend the cellular automaton model on one-dimensional lattice to the real-variable model on off-lattice (continuous-in space model) in order to take into account the fluctuation of vehicular speed. Vehicles extend over the highway when moving forward. The characteristics of traffic dispersion are derived. It is shown that vehicular traffic exhibits scaling property. When a vehicle accelerates for following the vehicle ahead, vehicles move forming a cluster without dispersion. The relationship between the width of vehicular cluster and acceleration rate is clarified.     

巨共振激发的相对论效应

在相对论量子场论(QHD)的框架下,得到了相对论线性Vlasov方程.基此计算了球形核¹⁶O、⁴⁰Ca、⁹⁰Zr及²⁰⁸Pb的巨偶极共振的强度函数分布.计算得到的巨共振中心能量,与实验结果比较有较好的符合.对计算结果作了简要的讨论,发现核子有效质量m^*和平均场自旋轨道耦合力对巨共振能量有着重要的效应.     

A Method for Quantitative Analysis of Chemical Mixtures with THz Time Domain Spectroscopy

A method for analysing chemical mixtures quantitatively with terahertz time domain spectroscopy is proposed. The experimental results demonstrate the feasibility of this technique. Transmission coefficient of THz wave at the sample surface is taken into account to improve the analytic precision, lsomer mixtures are chosen as the experimental samples. Compared to similar techniques, the analytic precision could be improved evidently in this method.