ENDOR study on the anion radical of benzo[c]cinnoline

The ENDOR spectrum was obtained for the benzo[c]cinnoline anion radicalin 1,2-dimethoxyethane. The hfs constants of the protons correspond with those found by EPR spectroscopy, and also agree well with the qualitative tendency of the reported spin density distributions by HMO calculation.     

Effect of doping on positron annihilation in GaAs

The effect of doping on positron annihilation was studied in GaAs single crystals. The positron lifetimes in Si- and Ge-doped crystals (n-type) are similar to that in an instrinsic crystal. On the other hand, the lifetimes in Zn-, Cd-, Cr- and Mn-doped crystals (p-type) are shorter than that in an intrinsic one. The difference is small but significant.     

Roughness and correlation-length determination of rough-surface objects using the speckle contrast

A method using the speckle contrast for the determination of both the roughness and the correlation length of surface-height variations of a rough-surface object is proposed on the basis of the statistical properties of the Gaussian speckle field in the image region. The expression for the speckle contrast is first theoretically derived in the optical imaging system as a function of the defocus distance and the surface parameters of the object. By solving the equations expressing the speckle contrasts at the image and defocus planes, a unique solution is found to exist for the roughness and the correlation length. In particular, a useful approximate relation that the roughness depends only on the contrast ratio is derived for relatively small values of the roughness. The experiments were performed to confirm the validity of the proposed method. The present method has an advantage of the simplicity in a measuring procedure where the contrasts at only the two points are required to determine the surface parameters.     

Intramolecular band mapping of poly(p-phenylene) via UV photoelectron spectroscopy of finite polyphenyls

Ultraviolet photoelectron spectra were measured of solid sexiphenyl with synchrotron radiation and of gaseous polyphenyls from biphenyl to sexiphenyl with a Hel light source. The similarity of the spectrum of the solid with the XPS spectrum of poly(p-phenylene) (PPP) shows the usefulness of sexiphenyl as a model compound of PPP. Examination of the fine structure observed in the low binding-energy region clearly shows how the electronic structure of the p-phenylenes evolves from that of benzene including the effects of deeper levels and of the non-planarity of the molecular geometry. The experimental E = E(k) energy band-dispersion relation of a PPP chain can be deduced by giving each energy level of the oligomers an appropriate k value. An extrapolation for the total bandwidth and the threshold photoemission energy of solid PPP yields 3.9₅ and 5.6₅ eV. respectively.     

Energy levels and γ-ray transitions in 147Pm

Gamma rays emitted in the decay of ¹⁴⁷Nd have been studied using Ge(Li) detectors as singles and coincidence spectrometers. Four new γ-rays of 53.1, 81.15, 149.4 and 191.24 keV have been detected and all incorporated into the decay scheme. Angular correlation measurements for the 275–319, 275–411 and 272–408 keV cascades have yielded the following result: A₂(275–319) = 0.006(2), A₄(275–319) = 0.005(5), A₂(215–411) = ?0.013(17), A₄(275–411) = ?0.008(30), A₂(272–408) = ?0.283(10) and A₄(272?408) = 0.015(18). From these coefficients the E2/M1 mixing ratios of the 272 and 275 keV γ-transitions have been determined to be 0.10(3) and 0.107(7), respectively, and the spin of the 680.43 keV level to be $\text{7}\text{2}$. Theoretical calculations on the intermediate coupling model for harmonic and anharmonic potential functions have been carried out and better agreement with experiment has been obtained for the anharmonic potential function.     

Laser fluordmetric systems for ultra-trace analysis

Laser fluorimetric systems with different exciting sources and signal processing systems are compared with rhodamine B as the standard, and detection limits are discussed. The combination of a nitrogen laser-pumped dye laser, a monochromator and a pulse-gated photon counter provides the highest sensitivity (0.04 ng l^-1). Optical filters, a boxcar detection system, or an argon laser with high average power are also effective when fast response times are required.     

The impurity-impurity interaction in aluminum

The interaction between a Cu atom and a Sn atom in aluminum was calculated by the pseudopotential method. It is shown that there is a rather weak coupling between these different types of impurity atoms.     

Synthesis and polymerization of allyloxyacetaldehyde

Allyloxyacetaldehyde (AOA) was synthesized by the Williamson reaction between sodium allyl alcoholate and bromoacetaldehyde dimethyl acetal. Highly reactive crystalline poly(allyloxymethyl)oxymethylene was obtained from AOA by using organoaluminum compounds as initiators at low temperature. The influence of initiators, solvents, and temperature on the polymerization was examined. Conspicuous exothermal behavior of the resulting polymer observed in the temperature range of 110–140°C in air with a differential scanning calorimeter, was not only due to an oxidative scission of the polyoxymethylene chain but also due to a chain reaction of neighboring allyl side groups in the polymer chain.