Mean power transmission for one-dimensional random wave propagation using a cumulant expansion

In this paper the problem of the mean power transmission for one-dimensional wave propagation in a random medium is studied. We use a cumulant technique valid for small k₀L_c where measures the size of the fluctuations, L_c is the correlation length of the random wave number, and k₀ is the undisturbed wave number. We obtain an integral expression for the mean transmitted power. It shows exponential decay for large width, and linear decay for small width. The relevant scale to measure the width of the slab is ²k²₀∫^∞₀C(x)cos(2k₀x)dx where C(x) is the autocorrelation of the random wave number.     

B(E2)-values of even-a nuclei with 82 neutrons

Coulomb excitation of the first excited 2⁺-state was measured usingα-particles to determine reduced transition probabilities,B(E2; 0 _gs ⁺ →2 ₁ ⁺ ), in nuclei with a closed shell of 82 neutrons. TheB(E2; 0 _gs ⁺ →2 ₁ ⁺ -values are 10.2 single-particle units (spu) for¹³⁸Ba, 13.5 spu for¹⁴⁰Ce, 11.9 spu for¹⁴²Nd and 11.6 spu for¹⁴⁴Sm. The uncertainty ranges from 1.3 % to 2.3 %.     

Temperature dependence of the hyperfine field in amorphous Fe2O3

Mössbauer spectroscopy was used to follow the hyperfine field at ⁵⁷Fe nuclei in amorphous Fe₂O₃. The value of H_hf at T = 0, 470 kG, indicates $\text{J}\text{=}\text{5}\text{2}$ for the Fe ions, while the reduced hyperfine field versus reduced temperature closely follows a $\text{J}\text{=}\text{1}\text{2}$ Brillouin function. This result is at variance with theoretical predictions for a spin glass and is also different from amorphous metals with a high content of magnetic ions as reported in the literature. Paramagnetic Mössbauer spectra of amorphous mixed oxides of Fe₂O₃ with ZnO and CoO show that the ⁵⁷Fe nuclei in all amorphous ferric oxides studied so far are coordinated in a manner similar to the d site in β F₂O₃, and distinctly different from the coordination in their crystalline form.     

Systematically weak temperature dependence of electric field gradients in distorted cubic metals

The temperature dependence of the electric field gradient for radiation-damaged copper and for the dilute alloy Zn$\text{Ag}$ has been measured using the perturbed angular correlation technique. A systematically weak temperature dependence is found for distorted cubic metals compared to non-cubic metals. The strong temperature dependence for the Zn$\text{Ag}$, In$\text{Ag}$ and Sn$\text{Ag}$ alloys as reported in literature has not been confirmed in the present experiment.     

Laser-induced fluorescence of metastable xenon ions

Xenon ions in the metastable state 5d ⁴D_{$\text{7}\text{2}$} are excited by means of a tunable dye laser at 6051 Å. The excitation is monitored by non-resonant fluorescence at 5292 Å.     

Influence of crystallographic displacement and g-factors on the groundstate of cerous magnesium nitrate

Since the thermodynamic properties of cerous magnesium nitrate play such an important role in low temperature physics we computed the influence of all variations still possible under the given set of known data: Small variation in the lattice structure, in particular the displacement of the center plane, small variations of the g-factor and the combination thereof.     

Losses of optical multimode strip-waveguides made by thick film technology

Loss measurements on straight and curved multimode strip-waveguides made from photosensitive sheets by a photolithographic process are reported. The cross section of the waveguides vary from 20 μm × 50 μm to 100 μm × 100 μm. The loss is detected by measuring the light scattered out of the waveguide. Waveguides fabricated by a modified technology are compared to conventional ones at wavelengths of 0.633 μm and 0.83 μm. Using the modified technology losses of 2 dB/cm at λ = 0.83 μm have been measured for both straight and curved (radius 30 mm) guides.     

Tunable light source for coherent anti-Stokes Raman scattering microspectroscopy based on the soliton self-frequency shift

We present a photonic crystal fiber (PCF)-based light source for generating tunable excitation pulses (pump and Stokes) that are applicable to coherent anti-Stokes Raman scattering (CARS) microspectroscopy. The laser employed is an unamplified Ti:sapphire femtosecond laser oscillator. The CARS pump pulse is generated by spectral compression of a laser pulse in a PCF. The Stokes pulse is generated by redshifting a laser pulse in a PCF through the soliton self-frequency shift. This setup allows for probing up to 4000 cm(-1) with a spectral resolution of approximately 25 cm(-1). We characterize the stability and robustness of CARS microspectroscopy employing this light source.