Optical phase conjugation in laser dyes

The nonlinear optical response of four laser-active dyes (Pyridine 1, DCM, Pyridine 2 and Styryl 9) is reported at a wavelength of 532 nm. The dyes show phase conjugate reflectivities in the 5 to 85% range. Polarization discrimination experiments and comparison with the Caro-Gower model suggests thermal origin of the nonlinearity.     

Study of C centres in NaCl by positron angular correlation

The nature of C centres in NaCl has been experimentally studied by the positron annihilation technique. The results are in support of a previously proposed model for the C centres [1]. The approximate size of C centres has been estimated to be of the order 6.3 ± 0.7 Å.     

Cohesion in lead chloride

The Born model is used as a method to assess the ionicity and the extent of covalent contribution to the binding in lead chloride. In the process, the Madelung constant (11·2429 with respect to cube root of unit cell volume) and cohesive energy (W _L) (484 kcal/mole) are evaluated. The theoreticalW _L, when compared with that derived from a thermochemical cycle indicates that PbCl₂ can be considered to be ‘predominantly ionic’.     

Formylation of polyhydroxy flavones and chromones

In the case of nor-wogonin and 5:7:8-trihydroxy-2-methylchromone, Gattermann method is efficient in yielding the corresponding aldehydes, whereas with their 8-methyl ethers hexamine method works satisfactorily.     

Determination of isoniazid and hydrazine by capillary electrophoresis with amperometric detection at a Pt-particle modified carbon fiber microelectrode

Capillary electrpphoresis (CE)/electrochemical detection (EC) for the simultane-ous determination of hydrazine and isoniazid has been developed.The electrochemical method uses a novel modified electrode dispersed with ultrafine platinum particles on the surface of a 30μm carbon fiber microelectrode.The unique characteristic of the Pt-particles modified carbon fiber microelectrode is its excellent stability.The current measurement for hydrazine is more sensitive than that of isoniazid.Selective determination of trace amount of free hydrazine in isoniazid and its formulation can be achieved at applied potential of 0.5V.     

Structural and compositional changes in ion-bombarded Ta2O5

A detailed study of the effect of heavy-ion bombardment on Ta₂O₅ has been undertaken using a combination of radioactive tracer techniques, electron microscopy, and Rutherford backscattering. Crystalline Ta₂O₅ is amorphized at ~6 × 10¹³ ions cm^?2, while at a dose of ~5 × 10¹⁶ ions cm^?2 the electron microscopy reveals the development of random grains of a new crystalline phase. By ~1 × 10¹⁷ ions cm^?2 the grains are not yet overlapping but still yield a diffraction pattern consistent with either δ-Ta-O (not to be confused with TaO) or Ta_1?xO₂, thus indicating that Ta₂O₅, like most other transition-metal oxides, is subject to preferential sputtering. Preferential sputtering was confirmed by backscattering analysis of specimens bombarded to high doses, where the average surface composition was found to be Ta_1.8±0.2O₂ or, equivalently, Ta₂O_2.2±0.2. The surface alteration had an average composition independent of the mass and energy of the incident ions.     

Evidence for resonance electron transfer in photon excited X-ray satellite spectra of fluorine compounds

The KαL¹/KαL⁰ intensity ratio of fluorine is measured in five fluorine compounds with a crystal spectrometer. An anomalous reduction of this intensity ratio was observed in KF and SrF₂, which is attributed to resonance electron transfer from the metal ion to the spectator vacancy in the fluorine ion. KαL²/KαL⁰ intensity ratio of fluorine is also measured. The measured relative intensities are compared with the theoretical estimates of Aberg. Formerly RSIC