Subpicosecond photon echoes by using nanosecond laser pulses

Subpicosecond time resolutions have been obtained in photon echoes when a sample was excited by two nanosecond dye laser pulses with a smooth and broad spectrum. The dye laser was pumped by second harmonics of a Q-switched Nd:YAG laser, and the pulse width was 10 ns. The sample was 3% Nd³⁺-doped silicate glass, and the center frequency of the dye laser was tuned at 5910 Å on resonance with the ⁴I_{$\text{9}\text{2}$} ? ²G_{$\text{7}\text{2}$}, ⁴G_{$\text{5}\text{2}$} transition of Nd³⁺. The homogeneous transverse relaxation time T₂ was measured to be 91 ps at 10 K in agreement with the previous measurements by picosecond pulses.     

Self‐polyaddition of triethylsilyl perfluoroisopropenyl ether

The results on radical self‐polyaddition reactivity of two trialkylsilyl perfluoroisopropenyl ethers, triethysilyl perfluoroisopropenyl ether [CF₂?C(CF₃)OSi(C₂H₅)₃] (FTEE) and dimethylphenylsilyl perfluoroisopropenyl ether [CF₂?C(CF₃)OSi(CH₃)₂C₆H₅] (DMPE), and two perfluoroisopropenyl carboxylates, 2‐butyroxypentafluoropropene [CF₂?C(CF₃)OCOC₃H₇] (BuFPP) and 2‐(methoxyacetoxy)pentafluoropropene [CF₂?C(CF₃)OCOCH₂OCH₃] (MFPP), are described. Radical self‐polyaddition of FTEE afforded a polymer as high as 1.87 × 10⁴ in molecular weight in the presence of radical generators such as benzoyl peroxide and di‐tert‐butyl peroxide. DMPE gave only addition products with initiating radicals. BuFPP and MFPP scarcely yielded even addition products with radical. The mechanism that the self‐polyaddition of FTEE was initiated by the addition of radical onto the perfluoroisopropenyl group followed by a 1,5‐shift to afford a methyl radical that attacked the perfluoroisopropenyl group of another FTEE molecule is proposed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2743–2754, 2003     

Iodoetherification of 4-penten-1,3-diols: stereoselective synthesis of cis 2-iodomethyl-3-hydroxytetrahydrofurans

cis 2-Iodomethyl-3-hydroxytetrahydrofurans have been obtained in high yields and in high selectivities by treatment of 4-penten-1,3-diols with iodine (ether-H₂O, NaHCO₃).     

Pressure-induced magnetic transition in Fe2P

The weak field ac susceptibility and the resistivity of Fe₂P single crystals were measured as functions of temperature from 4.2–300 K and as functions of hydrostatic pressures up to 20 kbar, using a newly designed clamp-type pressure cell. The Curie temperature, and the first-order transition temperature, decreased rapidly with increasing pressure, and ferromagnetism vanished at about 13 kbar at 0 K. A second-order transition temperature, as well as the first-order transition, appeared in the region below 170 K and above 5 kbar (triple point) and a new pressure-induced magnetic phase was found. The phase is proposed to be antiferromagnetic for reasons discussed in the paper.     

Total synthesis of manoalide and seco-manoalide

The first synthesis of manoalide and seco-manoalide from methyl 7,8-dihydro-β-ionylidene acetate was achieved in high yield by the new method utilizing regiospecific singlet oxygen oxidation of 3-alkenyl-5-trimethylsilylfuran to β-alkenyl-γ-hydroxybutenolide.     

Magnetization of CeAg at high pressure

Magnetization measurements for CeAg under hydrostatic pressures up to 4.0 kbar and CeAg_1?xIn_x compounds (0.01 ? x ? 0.20) at normal pressure were made at 4.2 K in magnetic fields up to 50 kOe. It was found that the magnetization of CeAg under pressure and of CeAg_1?xIn_x were larger than that of CeAg at normal pressure.     

Novel oxy-perfluoroalkylation

(Perfluoroalkyl)phenyliodonium sulfonates underwent novel oxy-perfluoroalkylation with alkenes under oxygen atmosphere in the presence of a base.     

High-energy dye laser pumped by wall-ablation lamps

A guideline for the optimum design of linear wall-ablation lamps is presented with a simple empirical formula which describes the luminescent characteristics of lamps. The absolute luminescent efficiency of the wall-ablation lamp was measured. A high-energy dye laser with a quadruple-elliptical cylindrical cavity was constructed using these lamps, and an output energy of 23.3 J (11.6 MW) was obtained with an overall efficiency of 0.31 %. The energy-flow diagram of this laser system was computed with a rate-equation analysis, and the conversion efficiency from electrical input to laser output was determined. One can expect an overall efficiency of about 2 %.