Gd thin films with different thickness （about 10 nm and 0.5 nm） were deposited on Si（100） by laser molecular beam epitaxy （LMBE）. Thickness dependence of the initial oxidation behaviors of Gd films was studied b...Gd thin films with different thickness （about 10 nm and 0.5 nm） were deposited on Si（100） by laser molecular beam epitaxy （LMBE）. Thickness dependence of the initial oxidation behaviors of Gd films was studied based on the in situ X-ray photoelectron spectroscopy （XPS） and ultraviolet photoelectron spectroscopy （UPS） analysis under ultra-high vacuum （UHV） condition. When the thin film is around 10 urn, the XPS results show that Gd is extremely reactive with oxygen forming Gd oxides and the oxides of Gd are easily hygroscopic. The UPS results show that the Gd 4fhas a double-peak structure and the double-peak structure of Gd 4fevolves into a single-peak feature after exposing to air. When the thickness of the Gd film decreases to about 0.5 urn, the reactivity of Gd film with oxygen is decreased by the diffusion of Si component into Gd layers based on the XPS and UPS results. It is suggested that the silicon atoms segregate at the grain boundaries of Gd film to form a barrier, which block the further diffusion of oxygen and water vapor into the Gd layers.展开更多
Erbium dihydride thin films were prepared by pulsed laser deposition on Si（100） substrates using erbium target under different low hydrogen pressures. The properties of these films were examined by atomic force micr...Erbium dihydride thin films were prepared by pulsed laser deposition on Si（100） substrates using erbium target under different low hydrogen pressures. The properties of these films were examined by atomic force microscopy, X-ray diffractometer, transmission electron microscopy, and Fourier transform infrared spectroscopy and UV-vis spectroscopy. Surface morphology reveals the smooth surface of these films （RMS： from 0.503 to 2.849 nm）. The presence of obviously-broadened peaks for diffraction planes （111） suggests a presence of very tiny crystallites distributed along a preferred crystallographic orientation. Transmission electron microscopy investigations confirmed the formation of tiny crystallites due to the implantation of erbium ions. Due to the increase of nominal H concentration, the intensity of the broad absorbance from 190-260 nm increased.展开更多
A type of non-axisymmetric oscillations of acoustically levitated drops is excited by modulating the ultrasound field at proper frequencies.These oscillations are recorded by a high speed camera and analyzed with a di...A type of non-axisymmetric oscillations of acoustically levitated drops is excited by modulating the ultrasound field at proper frequencies.These oscillations are recorded by a high speed camera and analyzed with a digital image processing method.They are demonstrated to be the third mode sectorial oscillations,and their frequencies are found to decrease with the increase of equatorial radius of the drops,which can be described by a modified Rayleigh equation.These oscillations decay exponentially after the cessation of ultrasound field modulation.The decaying rates agree reasonably with Lamb’s prediction.The rotating rate of the drops accompanying the shape oscillations is found to be less than 1.5 rounds per second.The surface tension of aqueous ethanol has been measured according to the modified Rayleigh equation.The results agree well with previous reports,which demonstrates the possible application of this kind of sectorial oscillations in noncontact measurement of liquid surface tension.展开更多
基金Funded by the Key Laboratory of National Defense Science and Technology(No.9140c6806080c68)
文摘Gd thin films with different thickness （about 10 nm and 0.5 nm） were deposited on Si（100） by laser molecular beam epitaxy （LMBE）. Thickness dependence of the initial oxidation behaviors of Gd films was studied based on the in situ X-ray photoelectron spectroscopy （XPS） and ultraviolet photoelectron spectroscopy （UPS） analysis under ultra-high vacuum （UHV） condition. When the thin film is around 10 urn, the XPS results show that Gd is extremely reactive with oxygen forming Gd oxides and the oxides of Gd are easily hygroscopic. The UPS results show that the Gd 4fhas a double-peak structure and the double-peak structure of Gd 4fevolves into a single-peak feature after exposing to air. When the thickness of the Gd film decreases to about 0.5 urn, the reactivity of Gd film with oxygen is decreased by the diffusion of Si component into Gd layers based on the XPS and UPS results. It is suggested that the silicon atoms segregate at the grain boundaries of Gd film to form a barrier, which block the further diffusion of oxygen and water vapor into the Gd layers.
基金Funded by the Fund of the Science and Technology on Plasma Physics Laboratory(No.9140C680501110C6803)
文摘Erbium dihydride thin films were prepared by pulsed laser deposition on Si（100） substrates using erbium target under different low hydrogen pressures. The properties of these films were examined by atomic force microscopy, X-ray diffractometer, transmission electron microscopy, and Fourier transform infrared spectroscopy and UV-vis spectroscopy. Surface morphology reveals the smooth surface of these films （RMS： from 0.503 to 2.849 nm）. The presence of obviously-broadened peaks for diffraction planes （111） suggests a presence of very tiny crystallites distributed along a preferred crystallographic orientation. Transmission electron microscopy investigations confirmed the formation of tiny crystallites due to the implantation of erbium ions. Due to the increase of nominal H concentration, the intensity of the broad absorbance from 190-260 nm increased.
基金supported by the National Natural Science Foundation ofChina(Grant Nos.50971105 and 50301012)the Foundation for the Author of National Excellent Doctorial Dissertation of China
文摘A type of non-axisymmetric oscillations of acoustically levitated drops is excited by modulating the ultrasound field at proper frequencies.These oscillations are recorded by a high speed camera and analyzed with a digital image processing method.They are demonstrated to be the third mode sectorial oscillations,and their frequencies are found to decrease with the increase of equatorial radius of the drops,which can be described by a modified Rayleigh equation.These oscillations decay exponentially after the cessation of ultrasound field modulation.The decaying rates agree reasonably with Lamb’s prediction.The rotating rate of the drops accompanying the shape oscillations is found to be less than 1.5 rounds per second.The surface tension of aqueous ethanol has been measured according to the modified Rayleigh equation.The results agree well with previous reports,which demonstrates the possible application of this kind of sectorial oscillations in noncontact measurement of liquid surface tension.
