Volume 86, Issue 5, 01 September 1999
Index of content:
86(1999); http://dx.doi.org/10.1063/1.371141View Description Hide Description
and single crystals are grown using the modified Bridgman method. The grownsingle crystals have orthorhombic structures. The energy band gaps for and single crystals measured at 298 K were about 0.789 and 0.798 eV, respectively, and these gaps are due to direct transitions. The Burstein-Moss effect due to overlapping of the energy level of ( and the conduction band of the is observed.
86(1999); http://dx.doi.org/10.1063/1.371142View Description Hide Description
We report the observation of interaction between a 1 GHz surface acoustic wave and vertical electron beams in a specially designed GaAsresonant tunneling structure. The interaction relies on the vertical component of the surface acoustic wave’s electric field to trigger a current through the structure. A theoreticalanalysis is presented that reveals the importance of both the spatial distribution of the surface acoustic wave potential and the nonlocality of the structure’s conductivity on the operation of the device. Possible applications of this interaction for signal processing and powerful microwave devices are discussed.
86(1999); http://dx.doi.org/10.1063/1.371143View Description Hide Description
The Lifshitz–van der Waals theory has been used to calculate the contact angles of dispersive liquids and solids: diiodomethane, α-bromonaphtalene, methylnaphtalene, benzene, and n-octane, liquids on polytetrafluoroethylene, polystyrene, polyisobutene, polyvinylchloride, and polyethylene. The theoretical calculation of the contact angles was based on the nonretarded Hamaker constants which have been calculated from the dielectric properties of the materials and application of the Lifshitz theory. These theoretical contact angles were compared with the experimental contact angles measured by the Wilhelmy plate method. Closely related values have been found for the theoretical and experimental contact angles.
86(1999); http://dx.doi.org/10.1063/1.371144View Description Hide Description
The watervaporization rate, an essential process for all the biological processes, was found to be significantly influenced under static magnetic fields up to 8 T in air and oxygen. The magnitude of the effect depended on the field–field gradient product rather than on B itself. Under forced flow conditions of the atmosphere, both enhancement and suppression of the vaporization rate were observed depending upon the direction of the gas flow relative to the field gradient. A mechanism is proposed to explain the results in a systematic manner based on the assumption of the creation of magnetic wind driven by the gradient susceptibility distribution caused by water content distribution in the atmosphere. It is discussed that this magneto enhancement of vaporization may be the indirect cause of frequently reported field effects on living organisms.