Simultaneous process of embossing and poling at elevated temperatures: a simple technique for nonlinear grating formation in polymer films

A simple technique for fabrication of nonlinear gratings in polymer films, based on simultaneous embossing and poling, is proposed and demonstrated. A master grating consisting of a metal electrode with a dielectric die was fabricated and used for repeated embossing of the grating structures into nonlinear optical polymers at elevated temperatures. At the same time, we applied high voltage to the polymer films to induce second-order nonlinearity. The grating profile and the nonlinearity were estimated, as well as the mass productivity of nonlinear gratings.     

Spin-wave description of nuclear spin-lattice relaxation in Mn12O12 acetate

In response to recent nuclear-magnetic-resonance (NMR) measurements on the molecular cluster Mn12O12 acetate, we study the nuclear spin-lattice relaxation rate 1/T(1), developing a modified spin-wave theory. Our microscopic new approach, which is distinct from previous macroscopic treatments of the cluster as a rigid spin of S=10, not only excellently interprets the observed temperature and applied-field dependences of 1/T(1) for 55Mn nuclei but also strongly supports the 13C NMR evidence for spin delocalization over the entire molecule.     

Absolute stereochemistry of allylic alcohols,amines, and other ene moieties: a microscale cross metathesis/exciton chirality protocol

A microscale chemical/chiroptical protocol for the determination of absolute configurations of allylic alcohols, amines, and related systems has been developed. The method is based on the conversion of the double bonds into a styrene, lambdamax 248 nm (epsilon 15 000), or other styrenoid chromophores by cross olefin metathesis. The obtained styrenoid chromophore then couples with the allylic acylate to yield a distinct couplet. The proposed method allows one to determine the absolute configuration of both moieties flanking the double bond. It also overcomes the restriction of the conventional allylic benzoate method that gives rise to weak CD couplet, for which in many cases only one wing of the couplet is observable.     

A facile formation of cyclic selenuranes and a cyclic selenurane oxide in the reaction of 2-methylseleno- and 2-phenylselenobenzoic acids and their derivatives with t-butyl hydroperoxide

The reaction of 2-methylselenobenzoic acid with 1,1′-carbonyldiimidazole followed by addition of t-butyl hydroperoxide gave cyclic selenuranes $\text{2a}$ and $\text{3a}$, suggesting the intramolecular insertion of the neighboring selenium atom into the OO bond of t-butyl 2-methylselenoperoxybenzoate. In the reaction of 2-phenylselenobenzoyl chloride with t-butyl hydroperoxide, cyclic selenurane $\text{2b}$ and the oxide $\text{7}$ were obtained.     

Charge-transfer bands observed with the intermolecular hydrogen-bonded systems between acetic acid and some aliphatic amines

Near and vacuum uv absorption spectra were measured for aliphatic amine-acetic acid systems in the gaseous state and in solution at room temperature. Equilibrium constants for complex formation were determined, and new absorption bands due to the hydrogen-bonded species between amines and acetic acid were observed near 170 nm in n-heptane and in acetonitrile, and at ～165 nm in the vapor phase. The new band of the triethylamine (TEA)-acetic acid system shifts to longer wavelengths in the order: in the vapor phase → in n-heptane → in acetonitrile. This is the reverse of the shift of the $\text{n-σ}{}^1$ band of TEA. The new band positions of the amine-acetic acid systems correlate to the ionization potentials of the amines. These facts together with theoretical results by the composite molecule method lead us to the interpretation that the new bands are the charge-transfer band characteristic of the hydrogen-bonded species.     

Measurement of polarized target asymmetry in γp → π+n below 1.02 GeV

The polarized target asymmetry for the process γp → π⁺n has been measured for incident photon energies below 1.02 GeV over a range of c.m. angles from 40° to 160°. π⁺ mesons from a polarized butanol target were detected by a magnetic spectrometer. The results are compared with predictions given by existing analyses. A tentative interpretation of the data is performed, and a larger contribution of S-wave resonances is suggested. The photocouplings of dominant resonances were hardly changed by the inclusion of new data and they seem to be almost uniquely determined.     

Philanthotoxins. A mass spectrometric investigation

A method employing liquid secondary-ion mass spectrometry (SIMS) in conjunction with metastable-ion measurements (linked scanning at constant B/E) to obtain sequence-specific information for three synthetic polyamine isomers was developed. The normal liquid SIMS spectra gave molecular weight information, but important sequence ions were of low intensity or obscured by the background. The metastable-ion spectra contained important fragment ions in particular due to cleavage along the polyamine chain. One of the three synthetic isomers was identical with a toxin present in the venom of the digger wasp. In conjunction with nuclear magnetic resonance spectroscopic studies, this should be a powerful method for the structural characterization of other closely related toxins present in the venom of this wasp.