Photoluminescence and luminescence excitation spectra in ZnSiP2

Summary Measurements of photoluminescence and luminescence excitation spectra of ZnSiP₂ have been performed at 4.2K and two results were obtained. One is the observation of a new sharp emission line at 1.980 eV, due to the bound exciton associated with the pseudodirect gap. The other is the observation of another new series of absorption lines in the luminescence excitation spectrum of an emission line, at 1.984 eV, in addition to those reported previously. These results indicate that in ZnSiP₂ radiative transitions occur at both the indirect and the pseudodirect gaps. Paper presented at the ?V International Conference on Ternary and Multinary Compound?, held in Cagliari, September 14–16, 1982.     

Temperature dependence of the positive-muon knight shift in MnSi

The temperature dependence of the μ⁺ Knight shift in weakly-helimagnetic MnSi has been measured in the temperature range between 28 and 300 K. The observed shift is found to be directly proportional to the host susceptibility in the paramagnetic state with a hyperfine coupling constant of —4.8 kOe/_μB.     

Chromogenic crown ether reagents for spectrophotometric determinations of sodium and potassium

Crown ethers carrying a phenolic group, 2-hydroxyphenoxymethyl-15-crown-5 and -18-crown-6, were synthesized. Introduction of nitro groups in the 3- and 5-positions of the aromatic nucleus or introduction of a 4-nitrophenylazo group in the 5-position gives a series of chromogenic reagents suitable for the extraction spectrophotometry of sodium and potassium. Sodium in human blood serum was successfully determined by using the (2-hydroxy-3,5-dinitrophenyl)oxymethyl-15-crown-5 reagent. The molar absorptivity of the sodium complex is 14 000 l mol^-1 cm^-1 at 423 nm.     

Hyperfine field and diffusion of μ+ in Fe single crystals

In recent positive-muon spin rotation experiment at TRIUMF on single crystal Fe, a clear temperature dependent change has been observed, for the first time, both in frequency and depolarization rates from 300 K down to 23 K. The μ⁺ depolarization was explained by the μ⁺ diffusion through inhomogeneous dipolar fields and the diffusion constant was found to obey an Arrhenius law (activation energy 17 meV) above 70 K but surprisingly deviated from this at lower temperatures, indicating quantum diffusion. We have also found that the μ⁺ hyperfine field has a temperature dependence slightly stronger than that of the magnetization.     

CW Operation of a Submillimeter Wave Gyrotron (Gyrotron Fu IV) for High Stability of the Output Frequency

The first cw operation of our submillimeter wave gyrotron (Gyrotron FU IV) using a 12 T superconducting magnet has been successfully carried out. Output power is more than 20 W at a frequency of 301 GHz in the TE₀₃₁ resonant cavity mode. Time-resolved frequency measurement s shows that the frequency fluctuation of the gyrotron output is smaller than 2 MHz. This frequency fluctuation is mainly due to the fluctuation in the output voltage of the power supply.     

A trend in the energy distributions of Ga dangling-orbital surface states on GaP,GaAs and GaSb (110)

Relaxed (110) surfaces of GaP, GaAs, and GaSb are studied by cluster calculations. Strongly localized surface states near the band gap are presented. It is shown that Ga dangling-orbital surface states can occur within the band gap as a result of a strong decrease in the anti-bonding character of surface Ga orbitals. A trend in the bond length on going from GaSb to GaP explains experimental data. Surface states associated with the group-V atoms are also described.     

The aggregations or crystals of metal-complex dye (C. I. Acid Yellow 161) on wool fibre

Summary The visible absorption spectra of dye crystals and the cross-section of wool fibre dyed with metal complex dye (C. I. Acid Yellow 161) were measured by means of a microspectrophotometer. The spectrum of crystal showed sharp and high maximum at 410 nm referred to as the peak from single crystal of the dye. The spectrum of the cross-section of dyed fibre showed two peaks of 410 nm (crystal-band) and 435 nm (monomeric state of the dye). Also, the electron diffraction pattern of the cross-section of dyed wool fibre showed the reflection ring of chromium. These results suggested that the dye should be present in the wool fibre in the monomeric, aggregate or crystalline state.

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Zusammenfassung Mit Hilfe des Mikrospektrophotometers wurden die Absorptionsspektren im Sichtbaren von Farbstoffkristallen und von Querschnitten der mit Metallkomplex-Farbstoff (C. I. Acid Yellow 161) gefärbten Woll-Fasern gemessen. Die Kristall-Spektren zeigen ein scharfes und hohes Maximum bei 410 nm, das der Bande des Farbstoffkristalls zugeordnet werden muß. Die Spektren der Querschnitte gefärbter Fasern zeigen zwei Banden: seine bei 410 nm (Kristallbande) und eine bei 435 nm (Monomerbande). Auch zeigen die Elektronenbeugungen an Querschnitten gefärbter Fasern die Ring des Chromes. Dies läßt vermuten, daß in den Wollfasern Monomeres, Aggregate oder Kristalle des Farbstoffs existieren.

     

Studies of optical properties of acridine orange-amylopectin sulfate complex

Summary From the studies of the circular dichroism and absorption spectra of acridine orange-amylopectin sulfate complex, we have deduced the following interesting explanation: If AO is situated in an environment which contains centers of asymmetry carbon atoms, it becomes optically active by induction.

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Zusammenfassung Aus Untersuchungen des Zirkulardichroismus und der Adsorptionspektren des Acridin-Orange-Amylopectin-Sulfat-Komplex folgt eine interessante Deutung. Wenn AO in asymmetrischer Umgebung gelagert wird, entsteht rege Aktivität.

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With 3 figures     

Non-secular part of nuclear dipolar broadening detected by zero-field spin relaxation of positive muon

The zero-field spin relaxation function of μ⁺ observed in ZrH₂ has revealed that the second moment of the nuclear dipolar broadening is five times larger than the high-field value. This experiment clearly demonstrates the recovery of the non-secular part of dipolar interaction between unlike spins. A general expression of zero-field relaxation function is presented to account for a slow modulation of random fields on μ⁺ found at room temperature.