Exact decoherence dynamics of a single-mode optical field

We apply the influence-functional method of Feynman and Vernon to the study of a single-mode optical field that interacts with an environment at zero temperature. Using the coherent-state formalism of the path integral, we derive a generalized master equation for the single-mode optical field. Our analysis explicitly shows how non-Markovian effects manifest in the exact decoherence dynamics for different environmental correlation time scales. Remarkably, when these are equal to or greater than the time scale for significant change in the system, the interplay between the backaction-induced coherent oscillation and the dissipative effect of the environment causes the non-Markovian effect to have a significant impact not only on the short-time behavior but also on the long-time steady-state behavior of the system.     

New search for processes violating the Pauli exclusion principle in sodium and in iodine

In this paper a new search for non-Paulian nuclear processes, i.e. processes normally forbidden by the Pauli Exclusion Principle (PEP), is presented. It has been carried out at the Gran Sasso National Laboratory of the INFN by means of the highly radiopure DAMA/LIBRA set-up (sensitive mass of about 250 kg highly radiopure NaI(Tl)). In particular, a new improved upper limit for the spontaneous non-Paulian emission rate of protons with energy E _p ≥ 10 MeV in ²³Na and ¹²⁷I has been obtained: 1.63 × 10⁻³³ s⁻¹ (90% C.L.). The corresponding limit on the relative strength (δ ²) for the searched non-Paulian transition is δ ²≲(3–4)×10⁻⁵⁵ (90% C.L.). Moreover, PEP-violating electron transitions in iodine atoms have also been investigated. Lifetimes shorter than 4.7×10³⁰ s are excluded at 90% C.L.; this allows us to derive the limit δ _e ²<1.28×10⁻⁴⁷ (90% C.L.). This latter limit can also be related to a possible finite size of the electron in composite models of quarks and leptons providing superficial violation of the PEP; the obtained upper limit on the electron size is r ₀<5.7×10⁻¹⁸ cm (energy scale of E≳3.5 TeV).     

Exploration of the sum of flexoelectric coef ficients of nematic liquid crystals

We present a theoretical calculation of the dependence of reflectivity Rpp of the improved fully leaky waveguide geometry,which comprises pyramid,matching fluid,and strongly anchored hybrid aligned nematic liquid crystal(NLC) cell on the internal angle.The calculation is based on the multi layer optical theory and the elastic theory of liquid crystals.For different sums of flexoelectric coefficients e11 and e33,the curve of Rpp moves a distance to the left or the right relative to the case of ignoring the flexoelectric effect and the distance of the movement varies with different flexoelectric coefficients.Consequently,the sum of flexoelectric coefficients can be explored by measuring the distance of the movement.     

Structure and properties of the surface alloy formed by irradiating a film/substrate system with a high-intensity electron beam

A film/substrate system has been treated with a submillisecond high-intensity electron beam. Examinations have shown that the electron-beam treatment of the film/substrate system resulted in alloying of the surface layer of the material throughout the melt which was accompanied by the formation of nanodimensional phases.     

保鲜膜材质及使用安全性的拉曼光谱分析

利用便携式拉曼光谱仪对聚乙烯(PE)、聚氯乙烯(PVC)、聚偏二氯乙烯(PVDC)和聚甲基戊烯(PMP)保鲜膜常温和不同条件下加热冷却后的拉曼光谱进行了对照分析。结果表明,应用便携式拉曼光谱仪在常温时可现场快速的对不同材质保鲜膜进行定性检测;同时还证明了聚氯乙烯(PVC)保鲜膜存在严重安全隐患,聚乙烯(PE)、聚偏二氯乙烯(PVDC)和聚甲基戊烯(PMP)保鲜膜为安全产品。     

6.17-W continuous wave operation of a 2132-nm c-cut Tm,Ho:YAP pumped by a laser diode of 794.3 nm

Continuous wave (CW) operation of a c-cut Tm (5 at %), Ho (0.3 at %):YAP laser at 2132 nm wavelength were reported in this paper. In the temperature of 77 K, the Tm,Ho:YAP crystal was double end-pumped by a 21.4 W fiber-coupled laser diode (LD) at the center wavelength of 794.3 nm. Different resonator lengths and output couplers for the total pump power were tried. The resonator length was 205 mm, and the maximum CW output power of 6.17 W was acquired, corresponding to an optical-optical conversion efficiency of 28.8% and a slope efficiency of 35.6%.     

Thermodynamical behavior of E′ centers in quartz from sediments: Potential for paleothermometry and geochronometry

The thermodynamical behaviors of E′ centers in 8 quartz samples from core XJ33-2-1 recovered in the Zhujiang Mouth Basin were measured by electron spin resonance (ESR) technique. The E′ ESR spectral intensity of samples before any laboratory treatment was measured and expressed asI ₁. The samples were then annealed at 300°C or 350°C for 60 min. The E′ ESR spectral intensity measured after this procedure is expressed asI ₂. The ratios ofI ₁, toI ₂ for the samples increase with the sample depth (from 320 to 3972 m), showing that there is a correlation between this ratio and the storage temperature of samples. Therefore the ratio ofI ₁/I ₂ can be used as an ESR paleothermometer. Besides the temperature, we must take into account the period of time for which the samples have been buried since their deposition, because we find that the ratiosI ₁/I ₂ (from 0.293 to 0.941) are closely related to the sediment ages (from 1.5 to 27.5 Ma), with a correlation coefficient of 0.98 or 0.99 obtained by linear or exponential regression, respectively. This relation can be explained by the increase of E′ center concentration in quartz samples with the sedimentation age.     

Study of synthetic diamonds by dynamic nuclear polarization-enhanced13C nuclear magnetic resonance spectroscopy

Four I_b-type synthetic diamond crystals were studied by dynamic nuclear polarization (DNP)-enhanced high resolution solid state¹³C nuclear magnetic resonance (NMR) spectroscopy. The home built DNP magic-angle-spinning (MAS) NMR spectrometer operates at a field strength of 1.9 T and the highest DNP enhancement factor of synthetic diamonds came near to 10³. Comparing with I_b-type natural diamonds, the¹³C NMR linewidths of synthetic diamonds in static spectra are broader. The¹³C spin-lattice relaxation time and DNP polarization time of synthetic diamond are shorter than those of I_b-type natural diamond. From the hyperfine structure of the DNP enhancement curve, four kinds of nitrogen-centred free radicals could be identified in synthetic diamond.     

傅里叶红外光谱法鉴别部分胡椒属生药的研究

利用共有峰率和变异峰率双指标,以胡椒属七种药用植物的红外指纹图谱为依据,计算出所测样品的共有峰率和变异峰率。建立了胡椒属七种药用植物共有峰率和变异峰率双指标序列,结果揭示了胡椒属七种药用植物的亲缘关系。中药海风藤与石南藤、大叶蒟根茎的共有峰率均在77%以上,变异峰率均在30%以下,此三种胡椒属药用植物亲缘关系较近;海风藤与胡椒根茎、十八症根的共有峰率在61%左右,亲缘关系稍远;海风藤与蒌叶根茎的共有峰率仅为44%。亲缘关系较远。利用红外二阶导数谱图,可以鉴别中药海风藤及其伪品石南藤、十八症根、大叶蒟根茎、胡椒根茎等品种。傅里叶红外光谱法可以对样品进行无损处理,不需要对药材进行复杂的提取分离过程即可提供化合物的官能团、类别、氢键等信息。该法能从整体水平分析谱图特征峰,具有分析速度快,重现性好,非破坏性和样品量小,制样简单,专属性强,节约成本,保护环境等优点。可以解决中药海风藤因资源短缺,伪品较多,鉴别困难等问题,也可为临床用药的安全、有效提供保障。傅里叶红外光谱法为胡椒属药用植物亲缘关系的探讨和真伪鉴别提供了一种新方法。符合中药向综合分析和整体分析发展的趋势。