On the low-temperature thermal conductivity of Ni-doped Al2O3

An attempt is made to explain the lower resonance anomaly in the thermal conductivity of Ni-doped Al₂O₃ by using τ_r ～ ω^-4s(ω² ? ω²_r)². An agreement between theory and experiment needs s = 0.71, and this is interpreted to mean that the frequency dependence of impurity-phonon coupling is approximately described by ω^0.71 for phonons having frequencies in close neighbourhood of ω_r.     

A generalized approach to beam wave interaction with a dielectric interface

New phenomena have been reported recently in connection with Gaussian beam interaction with a plane dielectric interface, namely, the deterioration of the reflected and refracted beams from shapes predicted by geometric optics, and the generation of higherorder components that cause angular beam deflection. Any bounded, symmetric beam, which is not necessarily Gaussian, can be comprised in terms of an angular spectrum of plane waves. Utilizing such a modal expansion, a model of the interaction process that seems to point out the generality of the phenomena involved for bounded symmetrical beams with any cross-section is presented. The procedure is applied to a Cauchy profile, and analytical results are given. Comparison with previous results obtained for the Gaussian beam and careful examination of the respective spectral functions demonstrate close correspondence between the results. This adds credence to the general approach presented here which can be applied to bounded symmetrical beams of general shape.     

Non-secular part of nuclear dipolar broadening detected by zero-field spin relaxation of positive muon

The zero-field spin relaxation function of μ⁺ observed in ZrH₂ has revealed that the second moment of the nuclear dipolar broadening is five times larger than the high-field value. This experiment clearly demonstrates the recovery of the non-secular part of dipolar interaction between unlike spins. A general expression of zero-field relaxation function is presented to account for a slow modulation of random fields on μ⁺ found at room temperature.     

Cyclotron damping of the space charge wave of a beam in a nonuniform magnetic field region

The space charge wave of an electron beam excited by the reactive medium instability in a uniform magnetic field region is observed to propagate into the region of increasing magnetic field. When the wave passes through the cyclotron resonance region, it suffers heavy cyclotron damping.     

Reaction mechanisms in the six-nucleon system with the multi-configuration resonating-group method

The properties of the six-nucleon system are examined with a multi-configuration resonating-group method consisting of thed+ configuration, thep+⁵He andn+⁵Li configurations, and deuteron pseudo-inelastic configurations. The main purpose is to study the reaction mechanisms in this system. The results obtained are quite satisfactory, with the calculatedd+ total reaction cross sections equal to around 90% of the empirically determined values. The one-nucleon transfer process turns out to be significantly more important than the deuteron direct-breakup process; however, the latter process must still be properly taken into consideration, since it does contribute to about one third of thed+ total reaction cross section. The process of one-nucleon transfer is shown to occur mainly in the peripheral region, while the process of deuteron direct-kreakup is found to take place predominantly in the interior region of the compound nucleus. The convergence property with respect to the number of deuteron pseudo-inelastic configurations has also been investigated. Here it is found that, with the dominant configurations included, the number of such configurations required can be rather small, which is an important finding because it greatly simplifies the computational aspects of multi-configuration resonating-group calculations.     

Nuclear moments of the neutron-deficient thallium isotopes

The nuclear moments of the neutron-deficient^187,188Tl isotopes were determined by measuring the hyperfine structure splittings of the λ=535 nm line in neutral thallium. An optical efficiency of 2×10⁻⁴ photons per radioactive ion was achieved using collinear fast beam laser spectroscopy with a large solid angle fiber optical array detector. Most of the moments can be interpreted fairly well in the single particle model.     

Phase dynamics of a detuned single-mode laser

We report measurements on the phase dynamics of a detuned single mode laser which has in the past shown correspondence to the complex Lorenz equation. The corresponding ranges of periodic pulsing, of detuned chaos and of windows within the chaotic domain are investigated.Invited paper     

Near-infrared photorefractivity in Cr-doped potassium sodium strontium barium niobate single crystal

We report on the photorefractive properties of a Cr-doped (K_1–x Na _x )_2A–2 (Sr _y Ba_1–y )_2–A Nb₁₀O₃₀ (x=0.586, y=0.659, A=1.12) single crystal in the near-infrared spectrum. The sample exhibits photorefractivity for wavelengths up to at least 840 nm where the steady-state two-beam coupling gain is found to be larger than 2 cm^–1. Photorefractive gain and decay rate are measured as a function of wavelength, grating spacing and intensity. The wavelength dependence of gain fluctuations in two-beam coupling are also measured.     

Intensities of rotational lines in first overtone bands for axially symmetric molecules of the group C3v

The interaction of vibration and rotation is considered in the computation of the intensities of rotational lines in the first overtone bands of axially symmetric molecules of the group C_3v. The calculation utilizes the contact transformation method through first order of approximation as outlines by Hanson and Nielsen. General formulas for the intensities of the lines in the first overtone bands 2ν_n and 2ν_m are obtained, where n and m denote normal modes of species A₁ and E, respectively. It is found that to this order of approximation the usual selection rules ΔJ = 0, ±1 and ΔK = 0 are observed for the parallel overtone band 2ν_n. For the overtone band 2ν_m, the selection rules are more complicated, being ΔJ = 0, ±1; Δl_m = 0 and ΔK = 0, Δl_m = ±2 and $\text{Δ}\text{K = ?1}$, or Δl_m = ±2 and ΔK = ±2.     

Metastable state and macroscopic quantum tunneling of binary mixtures

We provide a mixing model to explore the metastable state and the macroscopic quantum tunneling (MQT) of binary mixtures. For , we first observe the two condensates form the symmetry-breaking state (SBS) and then suddenly transfer to the symmetry-preserving state (SPS) through the MQT. The SBS is shown to be the metastable state in our system. We find the MQT does not spontaneously arise. The inducement mechanism is the damping but not the excitations. The damping mechanism can also control the lifetime and the tunneling decay rate of the SBS. Finally, we further present the origin of these phenomena by examining the energy of the system.