Direct determination of the phase of reflectivity by means of modulation technique

A method is described by which the phase of reflectivity for cubic crystals is measured. It involves modulated piezo-reflectance at the frequency ω₁ and modulation of the polarization of light with a $\text{1}\text{2}$λ-plate rotating with the frequency ω₂. The signal of frequency 2ω₂ yields the phase, and the signals of frequencies (ω₁± 2ω₂) yield the derivative of the phase. We have applied this method to measure the exciton spectra of ZnTe. It turns out that the phase becomes negative in certain spectral regions. This behaviour is interpreted in terms of Hopfield and Thomas' model of exciton free surface layers.     

Radiative and Auger transitions of core-excited states for the boron isoelectronic sequence

We introduce an approach for the characterization of quantum correlations in two-fermion systems based upon the state disturbances generated by the measurement of “local” observables (that is, quantum observables represented by one-body operators). This approach leads to a concept of quantum correlations in systems of identical fermions different from entanglement.     

Dynamical Auger emission induced by multistate vibronic coupling in the core-excited states of the BCl3 molecule

The Auger emission following the resonant excitation of the BCl3 molecule has been investigated using monochromatized synchrotron radiation. The B 1s excitation to the unoccupied Anti-bonding 4e(') orbital enhances the shoulder structure in the low kinetic energy side of the photoemission from the 2e(') valence bonding orbital. Based on a series of quantum mechanical calculations, this shoulder structure is interpreted as the dynamical Auger emission which reflects the B-Cl stretching nuclear motion and appears as a result of the purely multistate vibronic coupling effect among the Jahn-Teller split B 1s(-1)4e(') E' states and the closely lying B 1s(-1)3a(')(1) A'1 state.     

Quasistationary states and the range of pair interactions

"Quasistationary" states are approximately time independent out of equilibrium states which have been observed in a variety of systems of particles interacting by long-range interactions. We investigate here the conditions of their occurrence for a generic pair interaction V(r→∞)~1/r(γ) with γ>0, in d>1 dimensions. We generalize analytic calculations known for gravity in d=3 to determine the scaling parametric dependences of their relaxation rates due to two-body collisions, and report extensive numerical simulations testing their validity. Our results lead to the conclusion that, for γd-1 it is conditioned on the short distance properties of the interaction, requiring the presence of a sufficiently large soft core in the interaction potential.     

Measurement of total angular momentum values of high-lying even-parity atomic states of samarium by spectrally resolved laser-induced fluorescence technique

Spectrally resolved laser-induced fluorescence technique was used to uniquely assign total angular momentum (J) values to high-lying even-parity energy levels of atomic samarium. Unique J value assignment was done for seven energy levels in the energy region 34,800–36,200 cm⁻¹, recently observed and reported in the literature.     

自发喇曼成像法在线测量流场组分浓度

 介绍了自发喇曼成像技术实时监测流场组分浓度的方法,利用Nd：YAG脉冲激光器以及ICCD和光谱仪对大气进行了不同实验条件的测试,得到了影响谱线强度及测试精度的几个因素;得到了大气流场各主要成分的自发喇曼散射光谱和绝对浓度,测量误差小于8%。该技术可望在氧碘化学激光器单重态氧发生器物种浓度测定时得以应用以改善O₂(¹Δ)浓度测试精度较低的现状。     

自发喇曼成像法在线测量流场组分浓度

介绍了自发喇曼成像技术实时监测流场组分浓度的方法,利用Nd：YAG脉冲激光器以及ICCD和光谱仪对大气进行了不同实验条件的测试,得到了影响谱线强度及测试精度的几个因素;得到了大气流场各主要成分的自发喇曼散射光谱和绝对浓度,测量误差小于8%。该技术可望在氧碘化学激光器单重态氧发生器物种浓度测定时得以应用以改善O2(1Δ)浓度测试精度较低的现状。     

硼原(离)子内壳激发高自旋态能级和辐射跃迁

采用Rayleigh-Ritz变分方法计算了B原子(离子)内壳层激发高自旋态(~(4,5,6)L,L=S,P)里德伯系列的能量和精细结构劈裂,利用截断变分方法改进非相对论能量,并利用一阶微扰理论计算了相对论能量修正和质量极化效应修正,利用屏蔽的类氢公式计算了量子电动力学效应和高阶相对论效应,从而得到了高精度的组态能量.利用精确计算的波函数,计算了这些高自旋态的电偶极辐射跃迁波长、振子强度和辐射跃迁概率.通过长度规范和速度规范计算的振子强度的一致性证明了本文计算的波函数是精确的.相比其他理论计算结果,本文计算的高自旋态的能级及跃迁波长数据与实验数据符合得更好.对于一些高位的内壳层激发高自旋态,相关的能级和跃迁数据为首次报道,本文的计算结果对相关实验光谱谱线标定具有重要意义.     

Direct imaging of the tip shape by AFM

Direct imaging of the tip shape by AFM has been achieved using sharp pin-like structures present on copper films deposited on quartz by metal organic chemical vapor deposition (MOCVD).     

On the concepts of mass and linear momentum in Galilean thermodynamics

The paper presents a systematic treatment of the consequences of the first law of thermodynamics and of the Galilean principle of relativity for continuous bodies. It is shown that these two principles, when combined, imply not only the existence of energy, but also the existence of linear momentum. Both these quantities are represented by extensive state functions satisfying the equations of balance of energy and linear momentum, respectively. The linear momentum doesnot generally have the usual classical Newtonian form (mass times velocity). If, additionally, an assumption is made that the linear momentum is a function of velocity only, then the classical expression is recovered. The general equation of balance of linear momentum reduces then to Cauchy's equations of motion of continuum mechanics. But even without this additional assumption the concept of mass emerges as a derived concept in the theory: it figures in the transformation law for linear momentum under Galilean transformations.     

The energy and the linear momentum of space-times in general relativity

We extend our previous proof of the positive mass conjecture to allow a more general asymptotic condition proposed by York. Hence we are able to prove that for an isolated physical system, the energy momentum four vector is a future timelike vector unless the system is trivial. Furthermore, we allow singularities of the type of black holes.Supported in part by an NSF grant     

Measurement of through-going particle momentum by means of multiple scattering with the ICARUS T600 TPC

The ICARUS collaboration has demonstrated, following the operation of a 600 ton (T600) detector at shallow depth, that the technique based on liquid argon time projection chambers is now mature. The study of rare events, not contemplated in the standard model, can greatly benefit from the use of this kind of detectors. In particular, a deeper understanding of atmospheric neutrino properties will be obtained thanks to the unprecedented quality of the data ICARUS provides. However if we concentrate on the T600 performance, most of the ν_μ charged current sample will be partially contained, due to the reduced dimensions of the detector. In this article, we address the problem of how well we can determine the kinematics of events having partially contained tracks. The analysis of a large sample of atmospheric muons collected during the T600 test run demonstrates that, in case the recorded track is at least one meter long, the muon momentum can be reconstructed by an algorithm that measures the multiple Coulomb scattering along the particle’s path. Moreover, we show that momentum resolution can be improved by almost a factor two using an algorithm based on the Kalman filtering technique.PACS 29.40.Gx; 29.85.+c     

Low-spin states of 106Pd studied by the ARC technique

An average resonance capture (ARC) study of ¹⁰⁶Pd has been performed, resulting in the identification of a complete set of low-spin states (J^π = 0⁺–5⁺ and 1⁻–4⁻) up to an energy of 2.5 MeV. Several quasi-rotational bands have been tentatively identified. None of the bands can be positively identified as a rotational-like intruder configuration.     

Monitoring of the lifetimes of the metastable states in Au in an air-acetylene flame as a probe for local stoichiometric conditions by the laser-enhanced ionization technique

The behaviour of the lifetimes of the metastable 5d ⁹ 6s ^{2 2} D _3/2 and 5d ⁹ 6s ^{2 2} D _5/2 states in Au in an air/acetylene flame has been studied using the step-wise delayed laser-enhanced ionization technique. Using a new, fast and reliable, automated experimental procedure, we have conducted a systematic investigation of the lifetimes for various flame characteristics, namely lateral and vertical position in the flame and flame composition. It was found that the lifetimes of the metastable states are affected by at least three different mechanisms: i) a rather small but almost constant quenching rate, unaffected by the variations in the flame environment; ii) quenching by oxygen, which is proportional to the local partial pressure of oxygen; and iii) quenching by unburned fuel components. We have shown that by monitoring the lifetime of a metastable state as a function of various flame parameters, the conditions for local stoichiometry in the flame can be determined by this technique.     

Study of laser-induced plasma shock waves by the probe beam deflection technique

Laser probe beam deflection technique is used for the analysis of laser-induced plasma shock waves in air and distilled water. The temporal and spatial variations of the parameters on shock fronts are studied as functions of focal lens position and laser energy. The influences of the characteristics of media are investigated on the well-designed experimental setup. It is found that the shock wave in distilled water attenuates to an acoustic wave faster than in air under the same laser energy. Good agreement is obtained between our experimental results and those attained with other techniques. This technique is versatile, economic, and simple to implement, being a promising diagnostic tool for pulsed laser processing.