Adiabatic Mixing in the Liquid State

Adiabatic spin inversion has been used in the liquid state very efficiently for decoupling purposes. Here we show that it can also be adapted for spin mixing experiments, such as the TOCSY and clean TOCSY experiment, and is superior to previously employed mixing sequences. The main advantage of adiabatic mixing sequences over the conventional mixing schemes used in liquid state experiments is an extremely low sensitivity to RF field inhomogeneity and miscalibration of theB₁field strength. The method is evaluated experimentally by comparing results obtained with different mixing schemes in the basic 2D TOCSY experiment. In addition to higher reliability, adiabatic mixing provides a sensitivity improvement of ca. 20% as compared to conventional mixing schemes. This is explained by higher signal losses due to RF inhomogeneity in the experiments employing traditional mixing schemes. More significant sensitivity improvements can be expected in situations where RF homogeneity is traditionally poor, for example, in large volume probes and magnetic resonance imaging experiments.     

Technihadron production and decay at LEP2

The simple “straw-man” model of low-scale technicolor contains light color-singlet technihadrons, which mix with the electroweak gauge bosons. We present lepton collider production rates at the parton level, and show that experiments at LEP2 may be sensitive to the presence of technirho and techniomega states with masses 10–20 GeV beyond the center-of-mass energy because of the mixing. The exact sensitivity depends on several parameters, such as the technipion mass, the technipion mixing angle, and the charge of the technifermions. In an appendix, we describe the implementation of the model into the event generator PYTHIA for particle-level studies at lepton and hadron colliders.     

2-D homonuclear correlation and separated local field experiments for solids with strong homonuclear dipolar couplings

An experiment for acquiring two-dimensional homonuclear correlation spectra of nuclei in solids in the presence of strong homonuclear dipolar couplings is described. The experiment utilizes a multiple-pulse homonuclear decoupling sequence with an effective precession axis parallel to the rotating frame z-axis during the evolution and detection periods. A multiple-pulse sequence that suppresses chemical shift and heteronuclear dipolar coupling evolution and scales the static homonuclear dipolar coupling is proposed for the mixing period. The evolution during the mixing period is analogous to the dynamics of the mixing period in solution-state TOCSY experiments, and can be interpreted as the oscillatory exchange of longitudinal magnetization between coupled spins. For nuclides with large gyromagnetic ratios, the static homonuclear dipolar interaction will be substantially larger than the mechanisms used to develop internuclear correlations in solution state 2-D experiments, which should make it possible to establish correlations over much longer distances and with significantly shorter mixing times. Extensions to separated local field experiments are discussed.     

Size effect on electrochemical property of nanocrystalline LiCoO2 synthesized from rapid thermal annealing method

Nano-sizing of cathode materials for higher power Li-ion rechargeable batteries is an effective method to shorten a Li-ion diffusion path and achieve fast charge transfer. Nanocrystalline LiCoO₂ was synthesized through a combination of rapid thermal annealing method and a sol–gel method assisted with a triblock copolymer surfactant, and the electrochemical properties including the Li-ion chemical diffusion coefficient was investigated. Li-ion deintercalation/intercalation experiments suggested an extreme small amount of cation mixing between Li⁺ and Co³⁺ within a layered structure of LiCoO₂, which was not observable in the Raman spectroscopy. The analysis based on the solution for the diffusion equation of the cylinder model revealed that the cation mixing strongly decelerates the Li-ion diffusion in LiCoO₂.     

CONTRA: improving the performance of dynamic investigations in natural abundance organic solids by mirror-symmetric constant-time CODEX

We present a minor but essential modification to the CODEX 1D-MAS exchange experiment. The new CONTRA method, which requires minor changes of the original sequence only, has advantages over the previously introduced S-CODEX, since it is less sensitive to artefacts caused by finite pulse lengths. The performance of this variant, including the finite pulse effect, was confirmed by SIMPSON calculations and demonstrated on a number of dynamic systems.     

Measuring the sterile neutrino CP phase at DUNE and T2HK

The CP phases associated with the sterile neutrino cannot be measured in the dedicated short-baseline experiments being built to test the sterile neutrino hypothesis. On the other hand, these phases can be measured in long-baseline experiments, even though the main goal of these experiments is not to test or measure sterile neutrino parameters. In particular, the sterile neutrino phase \(\delta _{24}\) affects the charged-current electron appearance data in long-baseline experiment. In this paper we show how well the sterile neutrino phase \(\delta _{24}\) can be measured by the next-generation long-baseline experiments DUNE, T2HK (and T2HKK). We also show the expected precision with which this sterile phase can be measured by combining the DUNE data with data from T2HK or T2HKK. The T2HK experiment is seen to be able to measure the sterile phase \(\delta _{24}\) to a reasonable precision. We also present the sensitivity of these experiments to the sterile mixing angles, both by themselves, as well as when DUNE is combined with T2HK or T2HKK.     

Hadronic atoms and ticklish nuclei: The E2 nuclear resonance effect

The E2 nuclear resonance effect in hadronic atoms offers a way to increase the hadronic information that can be obtained from hadronic X-ray experiments. The effect occurs when an atomic deexcitation energy closely matches a nuclear excitation energy, so that some configuration mixing occurs. It shows up as an attenuation of some of the hadronic X-ray lines from a resonant versus a normal isotope target. A number of promising cases for ifπ^?, K^?, p?, and Σ^? atoms are discussed and a spectacular and potentially very informative experiment on p?-¹⁰⁰Mo is proposed.     

Results from solar, atmospheric and K2K experiments and future possibilities with T2K

Recent results from solar, reactor, atmospheric and long baseline (K2K) experiments are discussed. With the improved data statistics and analyses, our knowledge on the neutrino masses and mixing angles are steadily improving. T2K is the next generation neutrino oscillation experiment between J-PARC in Tokai and Super-Kamiokande. This experiment will start in 2009. This experiment is expected to improve the current knowledge on the neutrino masses and mixings substantially.     

Separation and suppression of coherent transfer effects in two-dimensional NOE and chemical exchange spectroscopy

A new method for the separation of coherent and incoherent magnetization transfer in two-dimensional (2D) NOE and chemical exchange spectroscopy is described. The new experiment differs from previous 2D exchange experiments, in that the mixing time τ_m is incremented systematically together with the evolution time t₁. This permits the distinction of the different orders of multiple-quantum coherence during the mixing time and allows the separation of coherent and incoherent transfer processes. The resulting clarification of chemical exchange and 2D NOE spectra is illustrated with experiments on small molecules and on a globular protein, the basic pancreatic trypsin inhibitor.     

AlI原子2D吸收谱的多通道量子数亏损理论分析

本文用多通道量子数亏损理论分析计算了AlI原子的²D吸收谱。采取具有三个不同电离阈的三个分解通道的混合模型。在适当选择了与能量有关的参数μ_α,D_α以及转换矩阵元U_iα之后,计算了第一电离阈和第二电离阈之间的²D自电离谱,并与Roig的测量结果作了比较。利用上述参数延伸到分立能域,得到²D能级的里德伯系列及其振子强度值。其结果与Lin和Weiss的分析以及相关的实验相符。 关键词：     

Direct Determination of Motional Correlation Times by 1D MAS and 2D Exchange NMR Techniques

One- and two-dimensional static and magic-angle spinning (MAS) exchange NMR experiments for quantifying slow (τ_c> 1 ms) molecular reorientation dynamics are analyzed, emphasizing the extent to which motional correlation times can be extracteddirectlyfrom the experimental data. The static two-dimensional (2D) exchange NMR experiment provides geometric information, as well as exchange time scales via straightforward and model-free application of Legendre-type orientational autocorrelation functions, particularly for axially symmetric interaction tensors, as often encountered in solid-state²H and¹³C NMR. Under conditions of MAS, increased sensitivity yields higher signal-to-noise spectra, with concomitant improvement in the precision and speed of correlation time measurements, although at the expense of reduced angular (geometric) resolution. For random jump motions, one-dimensional (1D)exchange-inducedsidebands (EIS)¹³C NMR and the recently developed ODESSA and time-reverse ODESSA experiments complement the static and MAS two-dimensional exchange NMR experiments by providing faster means of obtaining motional correlation times. For each of these experiments, the correlation time of a dynamic process may be obtained from a simple exponential fit to the integrated peak intensities measured as a function of mixing time. This is demonstrated on polycrystalline dimethylsulfone, where the reorientation rates from EIS, ODESSA, time-reverse ODESSA, and 2D exchange are shown to be equivalent and consistent with literature values. In the analysis, the advantages and limitations of the different methods are compared and discussed.     

在固体透明材料中利用级联四波混频方法获得宽带多色飞秒激光脉冲的研究

飞秒激光光谱学实验研究的深入与拓展对飞秒激光脉冲的要求也越来越高.比如多色抽运探测实验需要同时用到多个不同频率的超短飞秒激光脉冲.本文设计了一个更加简单紧凑的实验装置,对两束不同中心频率的入射光引入相反啁啾,在厚度为0.5 mm的CaF2晶体中利用级联四波混频获得了光谱半高全宽近100nm,支持傅里叶转换极限脉宽小于10 fs的多色飞秒激光脉冲.这一结果将为拓展飞秒激光光谱学研究和应用发挥重要作用.     

Low-lying excitations in the odd-odd nucleus154Eu

The analysis of experiments on parity mixing in compound nuclear resonances is described, with the nuclear spectroscopic aspects of the parity violation experiments emphasized. Expressions are derived for polarized neutron scattering and polarized neutron capture on unpolarized targets, and the resonance interference is treated explicitly. Examples are presented to illustrate the effects of entrance channel mixing for the case of target spin 1/2 and resonance spin 1. Results are also presented for targets with spins 0 and 3/2.     

The solar neutrino puzzle,the Mikheyev-Smirnov-Wolfenstein mechanism and the pseudo-dirac neutrino

We investigate the possibility that the small mass difference Δm² which appears in the MSW mechanism of resonant amplification of the neutrino oscillations in the sun is due to radiative corrections in models with a pseudo-Dirac neutrino. Using the constraints on Δm² and on the mixing angle θ we show that the mass of this neutrino must be of the order of one or a few eV. The consequences of this scenario for the forthcoming ⁷¹Ga solar neutrino experiments as well as for the neutrinoless double-beta decay experiments are also briefly discussed.     

Shock tube/laser absorption measurement of the rate constant of the reaction: H2O2 + CO2 2OH + CO2

We address the role of the linear mixing rule in the kinetics of the H₂O₂ decomposition system by reporting the rate constant for H₂O₂ + M = 2OH + M (M = Ar and CO₂) in the temperature range of 1087–1234 K at low pressures in a mixture of 20% CO₂ in Argon. The reaction rate constant was inferred from H₂O concentrations monitored by using a laser-absorption spectroscopy-based water diagnostic. To the best of our knowledge, this is the first measurement of the rate constant of this reaction in a mixture to be reported in literature. A significant discrepancy was found between the rate constants derived using the traditional linear mixing rule and the reduced pressure linear mixing rule. This discrepancy can have serious implications on the predictive accuracy of these kinetic models, especially under conditions relevant to the operation of supercritical CO₂ (sCO₂) power cycles that rely on oxy-fuel combustion in a working fluid comprised almost entirely of CO₂.     

Analysis of PNC neutron resonance experiments with polarized targets

The analysis of parity mixing experiments with unpolarized neutrons on polarized targets is described. Expressions for the neutron total cross section are presented for targets withI=1/2, 3/2, 5/2 and 7/2. These results are compared with the corresponding expressions for polarized neutron beams and unpolarized targets.     

Status of the T2K experiment

These lectures present the status of the Tokai to Kamioka Experiment (T2K) which just started taking data in early 2010. The goals and methodology for the experiment are presented as well as the challenges and prospects for determining the neutrino mixing parameters leading to neutrino oscillation with a particular attention to the determination of the mixing angle θ₁₃.     

Atmospheric neutrinos in the Soudan-2 and MACRO experiments

The results of Soudan-2 and MACRO experiments are summarized. Both experiments observe atmospheric neutrino anomalies in agreement with ν_μ → ν_τ oscillations with maximum mixing. The ν_μ → ν_s oscillations are disfavoured by the MACRO experiment at 98% C.L.     

Nuclear orientation of the rare-earth system^{160} Tb\underline {Tb} (sc)

We report precision nuclear orientation measurements on a bulk¹⁶⁰TbTb single crystal sample. The results of these experiments allow us to determine the hyperfine parameters for this system, as well as precise multipole mixing ratios for 22 gamma rays from the¹⁶⁰Dy daughter nucleus. Various methods of extracting the mixing ratios will be compared.