Toshimoto Kushida

Fast response temperature sensor

Measurements of temperature fluctuations in the atmospheric boundary layer are important for estimating many parameters including: heat flux, thermal stability, variability of refractive index, and temperature dissipation. In this paper we discuss the most commonly applied methods and some recently discovered difficulties that may be encountered in performing temperature fluctuation measurements above the ocean surface.

ZERO-FIELD ELECTRON MAGNETIC RESONANCE IN SOME INORGANIC AND ORGANIC RADICALS

Zero‐field electron magnetic resonance (EMR) spectra have been observed for several dilute paramagnetic systems. Among these are peroxylamine disulfonate ions in aqueous solutions, Cr3+ in single crystals of MgO, free radicals in x‐irradiated powders of malonic acid, potassium hydrogen malonate, dipotassium malonate, succinic acid, and glutaconic acid. Zero‐field spectra were observed by means of a marginal oscillator—detector similar to that of Benedek and Kushida. The zero‐field splittings in the systems studied were due exclusively to the hyperfine couplings between electronic and nuclear spins. Results obtained were in good agreement with high‐field EMR measurements on these systems. In several cases the hyperfine couplings were obtained with greater precision than at high field. In addition, the radical —OOC–ĊH–COO— was identified, for the first time, in irradiated dipotassium malonate by means of its zero‐field spectrum. No zero‐field lines could be detected in electron‐irradiated polyethylene. Adva...

Electromagnetic generation of ultrasonic waves in 3‐d transition metals

We investigated experimentally acoustic waves generated by electromagnetic means in the surface of 3‐d transition metals. The signal amplitude was greatest when the static magnetic field was normal to the generating surface. The amplitude increased in proportion to the external field only up to 3 kOe in both polycrystalline and single crystals of Ni, while there was a tendency for the signal to decrease at high fields. Generation efficiency in Ni improved with increasing temperature at low fields, but the amplitude observed at high fields decreased at high temperatures. The experimental results in ferromagnetic nickel are explained in terms of dynamic magnetostriction. Above the Curie temperature, the magnitude of the amplitude was accounted for by the Lorentz force mechanism applicable to nonmagnetic metals. The same mechanism also accounted for the amplitude observed in Fe and Co at room temperature. The results in ferromagnetic nickel are unique because of the large magnetostriction and small crystal a...

Volume dependence of the conduction electron spin susceptibility for Li and Na

Abstract The conduction electron spin susceptibility for Li and Na was measured as a function of pressure. The measured susceptibility enhancement is compared with the results of many-body theories. The volume dependence of electron wave functions at the nucleus is also derived experimentally.

Electromagnetic Generation of Ultrasonic Waves in 3‐d Transition Metals

Ultrasonic waves at megahertz frequencies can be generated in a metal by rf excitation of a coil placed next to the surface of the metal in the presence of a static magnetic field. We applied this technique to 3‐d transition metals. The observed results differ from those obtained previously from nonmagnetic metals. When the static field was normal to the generating surface, the amplitude of the acoustic waves observed in nickel increased in proportion to the field intensity only up to fields of 3 KOe, while there was a tendency for the signal to decrease at higher fields. This contrasts with the linear field dependence observed in nonmagnetic metals at room temperature. The amplitude was greatest when the field was normal to the surface. At room temperature electromagnetic generation was more efficient in nickel than in nonmagnetic metals (e.g., aluminum). Generation efficiency in nickel improved further with increasing temperature (below the Curie temperature TC) at low fields. However, the amplitude of ...

Nuclear spin lattice relaxation in multi-level system

Abstract It is shown that the rate equations for nuclear spin-lattice relaxation in multi-level system can be derived from the saturation recovery curves. These curves were observed for Al 27 NMR lines in an Al 2 O 3 single crystal at liquid He temperature. The values of the relaxation matrix elements in the rate equations were obtained from these curves. The conditions were derived which are necessary for these matrix elements to be derived from thermal transitions among the energy levels.