Showing papers by "Suet Yi Leung published in 1978"
TL;DR: In this paper, single crystals of KTb3F10, LiTbF4, LiTsb0.5Y0.75F4 and LiTsbs 0.25Gd0.25F4 were prepared and the wavelength, temperature, and magnetic field dependence of the Faraday rotation measured.
Abstract: Single crystals of KTb3F10, LiTbF4, LiTb0.5Y0.5F4 and LiTb0.25Gd0.75F4 were prepared and the wavelength, temperature, and magnetic field dependence of the Faraday rotation measured. Optical‐absorption spectra and refractive indices are also reported. The Faraday effect in these materials is described by a paramagnetic rotation with the primary oscillator strength arising from 4f8→4f75d electronic transitions of the Tb3+ ions. Whereas LiTbF4 orders ferromagnetically at low temperatures, the mixed crystals exhibited no ordering at T?1.25 K. Low‐temperature Faraday rotation measurements of KTb3F10 do not indicate ferromagnetic order above 1.66 K. KTb3F10 and LiTbF4 crystals have large Verdet constants, are transparent in the visible and near infrared and have small nonlinear refractive‐index coefficients. These materials are therefore useful for optical rotators and in high‐power laser applications.
38 citations
TL;DR: In this article, the energy and oxygen-pressure dependence of Balmer radiation photon yield due to ion-surface collisions on polycrystalline molybdenum using hydrogen atomic and molecular ions were measured in the energy range from 200 to 10 keV.
Abstract: The energy and oxygen-pressure dependence of Balmer radiation photon yield due to ion-surface collisions on polycrystalline molybdenum using hydrogen atomic and molecular ions were measured in the energy range from 200 to 10 keV. These results, obtained under ultrahigh-vacuum conditions, provide new information on the ways in which the photon yield is produced by electronic interactions of the emerging particles with the surface. Radiation yield, normalized to current and backscatter yield, varied in a consistently exponential manner over the entire incident-ion energy range. The molecular state and the charge state of the incident particles were measured to have no discernable effect on the final excitation for clean surfaces. At partial pressures of oxygen below 10/sup -11/ Torr, surface concentrations of oxygen below 2% of a monolayer on molybdenum could be maintained during the experiments. Increased surface coverages (up to 0.5 to 1 monolayer) raised the photon yield for molybdenum by a factor of 7. These oxygen-dependent effects are tentatively interpreted as owing mainly to changes in the deexcitation probability in the vicinity of the surface.
27 citations