Total deposition velocities and scavenging ratios of 7Be and 210Pb at Rokkasho, Japan

The atmospheric concentrations and deposition fluxes of ⁷Be and ²¹⁰Pb were observed biweekly in Rokkasho, Japan on the Pacific Ocean coast at the northern end of Honshu Island, from March 2000 to March 2006, to clarify their regional features. Seasonal variation pattern of atmospheric ⁷Be concentrations had double peaks, and that of ²¹⁰Pb had a single peak. Deposition fluxes of ⁷Be and ²¹⁰Pb showed the same patterns. The total deposition pattern of ⁷Be was similar to that commonly seen on the Pacific Ocean side of northern Honshu Island, while the pattern of ²¹⁰Pb was similar to that commonly seen on the Japan Sea side. The lack of high spine mountains windward in Rokkasho may be the cause of this ambiguity in the winter monsoon season. Total deposition velocities and scavenging ratios of ²¹⁰Pb were similar to those of ⁷Be from spring to fall, and showed that both nuclides had a similar removal process from the atmosphere. However, the scavenging ratios of ²¹⁰Pb were slightly larger than those of ⁷Be in winter, indicating different behaviors for both nuclides in the scavenging process. The scavenging ratios of both nuclides inversely correlated with precipitation rate, and the ratios in winter were larger than in the other seasons.     

Disorder in crystalline phases of chiral glass formers 5CB and 8OCB evidenced by the low temperature heat capacity

The heat capacity of two glass formers 5^*CB and 8^*OCB, each of which has two crystalline polymorphs (phases I and II) as well as a glass phase, was determined between 0.35 K and 20 K. The T-linear term of the heat capacity becomes significant below 1 K for both glasses. The glassy crystalline phase II of 5^*CB also shows such contribution, which is consistent with the existence of a residual entropy. Unexpectedly, however, the ‘stable’ phase II of 8^*OCB shows the similar contribution, indicating that this phase is disordered, whereas the glassy crystalline phase I shows no such contribution.     

Isotope-dependent crystalline phases at ambient temperature: Spectroscopic and calorimetric evidence for a deuteration-induced phase transition at 320 K in α-DCrO2

The heat capacities of HCrO₂ and DCrO₂ have been measured at temperatures between 5 and 360 K. A lambda anomaly occurred at 320 K for DCrO₂ but not for HCrO₂. Infrared spectra were recorded at temperatures between 5 and 405 K. The spectrum of DCrO₂ changed at 320 K with respect to the peak wave-number and splitting of some of the vibrations, while those of HCrO₂ depended smoothly on temperature. These experimental results are discussed in terms of a deuteration-induced phase transition.     

Infrared laser radar technique using heterodyne detection for range-resolved sensing of air pollutants

An infrared, pulsed heterodyne laser radar using differential absorption technique with tunable lasers is proposed as a practical means of measuring dispersed air pollutants with range resolution. A system analysis shows that this scheme offers an adequate sensitivity for ranges up to several km.     

Analysis of coherent Raman propagation effect

A theoretical analysis of coherent Raman propagation described by two classes of the well-known hyperbolic secant solution and elliptic solutions are presented.     

Frequency metrology with a turnkey all-fiber system

The repetition rate and carrier-envelope phase offset frequencies of a turnkey, all-fiber-based continuum generator were phase locked to a hydrogen maser. The frequency of the hydrogen maser was calibrated with a highly stable cesium atomic clock, and therefore a fully phase-locked optical frequency comb with well-defined absolute frequencies was obtained. In contrast with the commonly used Ti:sapphire-laser-based systems, we have accomplished a fully turnkey system with no user-adjustable parts. To evaluate the performance of this novel system, we performed absolute frequency measurements in the telecommunications region and at 1064 nm and compared them with our traditional Ti:sapphire-based comb.     

Broad-spectrum frequency comb generation and carrier-envelope offset frequency measurement by second-harmonic generation of a mode-locked fiber laser

A frequency comb spanning more than one octave has been achieved by injecting the second-harmonic generation (780 nm) of a mode-locked fiber laser (1.56 microm) into a photonic crystal fiber. We propose and realize a novel interferometric scheme for observing the carrier-envelope offset frequency of the frequency comb. Frequency noise has been observed on the measured carrier-envelope offset frequency, which has been confirmed to be generated in the photonic crystal fiber by comparing the measured beat frequencies between cw lasers and frequency combs before and after the photonic crystal fiber. The mode-locked fiber laser is considered to be an important candidate for the light source used in realizing a compact optical frequency measurement system including applications in the telecommunication bands.     

Reactions of hydropolysilanes with alcohols catalysed by tris(triphenylphosphine)chlororhodium

[RhCl(PPh₃)₃] is a very effective catalyst for the cleavage of Si-Si bonds by alcohols.     

Heat capacity measurements of MnxFe3−xO4

Heat capacities of Mn_xFe_3?xO₄ with the composition x = 1.0, 1.5, and 2.0 were measured from 200 to 740 K. λ-type heat capacity anomalies due to the ferri-paramagnetic transition were observed for all the compositions. The transition temperatures were 577, 471, and 385 K for the composition x = 1.0, 1.5 and 2.0, respectively, which are in good agreement with the results of magnetic measurements. The difference in heat capacities between the different samples was small except for the temperature range of the transition. The magnetic contribution to the observed heat capacity was obtained by assuming that the heat capacity can be expressed by the sum of the lattice heat capacity C_v (l), the dilation contribution C(d), and the magnetic contribution C(m). Entropy changes due to the transition were obtained from C(m) as 55.5, 50.7 and 49.2 J K^?1 mole^?1 for the composition x = 1.0, 1.5, and 2.0, respectively. The entropy changes were also calculated by assuming the randomization of unpaired electron spins on each ion, but they were from 6 to 10 J K^?1 mole^?1 smaller than the observed ones. The difference between the experimental and the calculated values is roughly explained by taking into account the cation exchange reaction between the tetrahedral and the octahedral sites in the spinel structure.