Hyperfine structure of antiprotonic helium revealed by a laser-microwave-laser resonance method

Using a newly developed laser-microwave-laser resonance method, we observed a pair of microwave transitions between hyperfine levels of the (n,L)=(37,35) state of antiprotonic helium. This experiment confirms the quadruplet hyperfine structure arising from the interaction of the antiproton orbital angular momentum, the electron spin and the antiproton spin as predicted by Bakalov and Korobov. The measured frequencies of nu(+)(HF)=12.895 96+/-0.000 34 GHz and nu(-)(HF)=12.924 67+/-0.000 29 GHz agree with recent theoretical calculations on a level of 6x10(-5).     

Primary processes of laser-induced selective dimer-layer removal on Si(001)-(2x1)

Excitation with nanosecond-laser pulses at fluences well below the melt threshold removes Si dimers on the Si(001)-(2x1) surface and induces atomic-Si desorption through an electronic mechanism. The rate of this photoinduced reaction depends superlinearly on the excitation intensity, and is enhanced resonantly at the photon energy where the optical transition injects holes into the dimer backbond surface-band state. The results reveal the crucial role of surface holes and their nonlinear localization in the bond rupture of Si dimers on this surface.     

Primary populations of metastable antiprotonic (4)He and (3)He atoms

Initial distributions of metastable antiprotonic (4)He and (3)He atoms over principal (n) and angular momentum (l) quantum numbers have been deduced using laser spectroscopy experiments. The regions n = 37-40 and n = 35-38 in the two atoms account for almost all of the observed fractions [(3.0 +/- 0.1)% and (2.4 +/- 0.1)%] of antiprotons captured into metastable states.     

Broadband waveguide intersections with low cross talk in photonic crystal circuits

We propose a new mechanism for constructing waveguide intersections with broad bandwidth and low cross talk in photonic crystal (PC) circuits. The intersections are created by combination of coupled-cavity wave-guides (CCWs) with conventional line-defect waveguides. This mechanism utilizes the strong dependence of the defect coupling on the field pattern in the defects and the alignment of the defects (i.e., the coupling angle) in CCWs. By properly designing the defect mode, we demonstrate through numerical simulation the establishment of such a waveguide intersection in one of the most useful PCs, which is based on a two-dimensional triangular lattice of air holes made in a dielectric material. The transmission of a 500-fs pulse at ~1.3 microm is simulated by use of the finite-difference time-domain method, showing negligible distortion and low cross talk.     

A novel synthesis of (E)-3,7-dimethyl-2-octene-1,8-diol secreted by the african monarch using the ring-opening reaction of α-methyl-β-propiolactone

The regioselective ring-opening reaction of α-methyl-β-propiolactone with 3,3-ethylene-dioxybutylmagnesium bromide in the presence of copper(I) catalyst afforded 2-methyl-6-oxoheptanoic acid, which was easily converted into (E)-3,7-dimethyl-2-2-octene-1,8-diol in good yield.     

Preparation of Na+-selective electrodes by ion-implantation of lithium and silicon into single-crystal alumina wafer and its application to the production of ISFET

Summary Sodium ion-selective electrodes (Na⁺-ISE) were prepared by implanting Si⁺ and Li⁺ into alumina wafers and their characteristics were investigated. The alumina wafer had a thickness of 100 m and a diameter of 1.40 cm. The ionselective membrane was produced by ion-implanting of Li⁺ and Si⁺ on both sides of a single-crystal alumina wafer. The total doses of Li⁺ and Si⁺ were controlled to be the same, viz. 10¹³–10¹⁵ ions/cm². The ion-implanted alumina wafer with 10¹⁴ or 4×10¹⁴ ions/cm² of Li⁺ and Si⁺ showed better characteristics than the others.The response curves of the 10¹⁴ ions/cm² implanted alumina wafer had a slope of 42 mV/pNa in a concentration range from 1–10^–4mol/l. The full response achieved after about 1 min was reproducible. The proposed idea of producing Na⁺-ISE by ion-implantation technique was applied to functuate the gate surface of the field effect transitor to sodium ion. The sodium ion-sensitive FET (Na⁺-ISFET) prepared by implanting Li⁺ and Al⁺ at a dose of 5×10¹⁴ ions/cm² showed a slope of 30 mV/pNa in a concentration range from 1–10^–4mol/l.

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Herstellung Na⁺-ionenselektiver Elektroden durch Einbau von Lithium und Silicium in Einkristall-Alumniumoxidblättchen und Anwendung zur Erzeugung von ISFET

Zusammenfassung Na⁺-selektive Elektroden wurden durch Einbau von Si⁺ und Li⁺ in Aluminiumoxidblättchen hergestellt und ihre Charakteristiken untersucht. Die Blättchen hatten eine Dicke von 100 m und einen Durchmesser von 1,40 cm. Ebenso wurde die Membran für einen ISFET hergestellt. Die Gesamtmenge von Li⁺ und Si⁺ wurde auf 10¹³–10¹⁵ Ionen/cm² eingestellt, wobei sich bei 10¹⁴ oder 4×10¹⁴ Ionen/cm² die beste Charakteristik ergab.Die Responsekurven der mit 10¹⁴ Ionen/cm² versehenen Aluminiumoxidplättchen hatten eine Neigung von 42 mV/pNa in einem Konzentrationsbereich von 1–10^–4mol/l. Der nach 1 min erhaltene volle Response war reproduzierbar. Die vorgeschlagene Technik wurde zur Einstellung der Gate-Oberfläche des Feldeffekt-Transistors auf Natriumion benutzt. Der Na⁺-sensitive FET (Na⁺-ISFET), der durch Einbau von Li⁺ und Al⁺ mit 5×10¹⁴ Ionen/cm² hergestellt wurde, zeigte eine Neigung der Signalkurve von 30 mV/pNa in einem Bereich von 1–10^–4mol/l.

     

QUANTUM EFFICIENCY FOR THE PHOTOCONVERSION OF BACTERIORHODOPSIN AT VERY LOW TEMPERATURES

Abstract— Quantum efficiencies for photoconversion of bacteriorhodopsin (trans-bR) to a bathochromic product (batho-bR^t) and its photoreversion in purple membrane at 77 and 9 K were investigated with low temperature spectrophotometry. The kinetics of the photoconversion and its photoreversion cannot be expressed by a single exponential curve. The photoconversions at 77 and 9 K showed the same slope in the early stage. The kinetics of the photoreversions were identical at the two temperatures. These results indicate that the quantum efficiencies for the conversion of trans-bR to batho-bR^t or for its photoreversion are identical at the two temperatures.
The fact that the photoreversion cannot be expressed by a single exponential curve suggests the existence of several conformational states of batho-bR^t due to the trimer structure of the purple membrane.     

Auger and secondary electrons excited by backscattered electrons; An approach to quantitative analysis

The contribution of backscattered electrons (BE) to Auger electrons (AE) and secondary electrons (SE) was studied by depositing Be onto a polycrystalline or deposited Cu substrate. The effects of backscattering on SE and maximum escape depth of SE were obtained by using the so called δ-η method. This method was also applied to the AE and the effects of BE on AE were experimentally evaluated. The AE yield versus primary energy curve which was corrected for BE was compared with other experiments and theories and considerably good agreement was obtained. From this analysis, the excitation efficiencies of AE by primary electrons and by BE could also be obtained. The absolute AE yield of Be (KVV) was estimated by “area” measurements. The changes of plasma losses, the elastic peaks, the energy distribution of BE, and the true SE were also observed as a function of deposited film thickness, and the results are discussed.