Atom—Field Correlations in the Weak-Excitation Limit of Absorptive Optical Bistability

We calculate the steady-state and first-order time varying atom—field correlation functions in the weak-excitation limit of absorptive optical bistability from a linearized theory of quantum fluctuations. We formulate a Fokker—Planck equation in the positive P representation following the phase-space analysis in [H. J. Carmichael, Phys. Rev. A 33, 3262 (1986)], which is suitable for the determination of cross-correlations as it does not resort to adiabatic elimination. Special emphasis is placed on the limit of collective strong coupling as attained from a vanishing photon-loss rate. We compare to the cavity-transmission spectrum with reference to experimental results obtained for macroscopic dissipative systems, discussing the role of anomalous correlations arising as distinct nonclassical features.

     

Random walks on inhomogeneous lattices

For lattices with two kinds of points (black and white), distributed according to a translation-invariant joint probability distribution, we study statistical properties of the sequence of consecutive colors encountered by a random walker moving through the lattice. The probability distribution for the single steps of the walk is considered to be independent of the colors of the points. Several exact results are presented which are valid in any number of dimensions and for arbitrary probability distributions for the coloring of the points and the steps of the walk. They are used to derive a few general properties of random walks on lattices containing traps.Presented at the Symposium on Random Walks, Gaithersburg, MD, June 1982.     

Vibrational relaxation study in 4-chloroacetophenone

Vibrational relaxation process has been emerged as a useful tool in probing the nature of solute solvent interactions in liquid phase. The Laser Raman techniques have been used to study the vibrational and rotational frequencies of molecules, which provide detailed information about the dynamic processes involved in liquids. Raman spectra of C=O stretching mode of 4-chloroacetophenone dissolved in acetonitrile and chlorobenzene have been recorded as a function of solvent concentration ranging from 10% to 90% concentration at room temperature. The 4-chloroacetophenone is a molecule having wide application in manufacture of drugs, perfumes and cosmetics. This study may provide useful information about the vibrational relaxation mechanisms in liquid solutions at molecular level. The Laser Raman components were determined and the spectra were analyzed at different solvent concentrations. The theoretical models have been tested and compare with the experimental results.     

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.     

Etude comparative des proprietes magnetiques des oxydes lamellaires ACrO2 (A = Li,Na, K)—I: Etude par effet Mössbauer de LiCrO2 dope par le fer

A Mössbauer study of the dimensionality of magnetic interactions in the layer oxide LiCr_0.99Fe_0.01O₂ shows a 2-D behaviour.     

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.