Wu Jin-Lei

Low-Field Emission from Iron Oxide-Filled Carbon Nanotube Arrays

Arrays of multi-walled carbon nanotubes (MWCNTs) filled with iron oxide have been fabricated by a one-step route based on the pyrolysis of ferrocene under a well-chosen synthesis condition. The MWCNT arrays were observed with a scanning electron microscope, with which an energy dispersive x-ray spectrum (EDXS) was also acquired, and they are analysed by x-ray diffraction. Furthermore, individual MWCNTs were studied by using selected area electron diffraction (SAED) and the EDXS in a transmission electron microscopy observation. All the observation and analysis confirmed that the MWCNTs were filled with iron oxide. Field emission from these arrays of iron oxide-filled MWCNTs was measured and the turn-on field was determined to range from 0.83–1.01 V/μm, appearing to be much lower than those of arrays of pure MWCNTs and arrays of nitrogen-doped MWCNTs fabricated in similar ways. The possible reasons of the observed low-field emission are discussed.

Fluorescence Microscopy of Nanoscale Silver Oxide Thin Films

The experimental conditions for photoactivated intermittent fluorescence from nanoscale silver oxide were studied with fluorescence microscopy. Strong fluorescence was observed from the Ag2O particles with size of 10-20 nm excited with both blue and green light. We observed the saturation of photoexcitation with blue light and explained the experimental results using the model of agglomeration of silver atoms to form small clusters and the fluorescence of Ag2 and Ag3 clusters.

Structure and Electrical Properties of Gold Nanowires Grown with Electrochemical Deposition

The effect of Al substitution for Fe on the structure, magnetostriction, anisotropy and spin reorientation of a series Of Tb-0.3 Dy-0.7 (Fe1-xAlx)(1.95) alloys (x = 0, 0.05, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35) at room temperature has been investigated. It was found that all the compositions of Tb-0.3 Dy-0.7 (Fe1-xAlx)(1.95) substantially retained the MgCu2-type C-15 cubic Laves phase structure and the lattice constant increases with increasing x. The substitution of Al increases slightly the magnetostriction in low magnetic field ( H less than or equal to 40kA.m(-1)) when x 0.15. The intrinsic magnetostriction lambda(111) decreases sharply also with incresasing x. The Mossbauer spectra show that for 0 less than or equal to x 0.15. The measurements of relative susceptibility indicate that the temperature of spin reorientation decreases with increasing x.

Theoretical dependence of long wavelength photoemission upon the size of Ag nanoparticles embedded in BaO semiconductor thin film

The dependence of long wavelength photoemission upon the size of Ag nanoparticles embedded in a BaO semiconductor is predicted and discussed theoretically. The calculated results show that the increase in the diameter of the Ag nanoparticle, in the range from 1.5 to 37.0nm, leads to the emergence of a roughly Gaussian form of the photoemission spectra and the peaks become markedly narrower. The results also show that the increase in the diameter of the Ag nanoparticle leads to the decrease of the long wavelength threshold. The incident light wavelength corresponding to the peak value of the photoemission gets bigger with the increase of the size of Ag nanoparticles, thus showing a redshift.

Field-ion microscopy observation of single-walled carbon nanotubes

Field-ion microscopy (FIM), a tool for surface analysis with atomic resolution, has been employed to observe the end structure of single-walled carbon nanotubes (SWCNTs). FIM images revealed the existence of open SWCNT ends. Amorphous carbon atoms were also observed to occur around SWCNTs and traditional field evaporation failed to remove them. Heat treatment was found to be efficacious in altering the end structures of SWCNT bundles. Carbon and oxygen atoms released from heated tungsten filament are believed to be responsible for the decoration imposed on the SWCNT ends.

Coherent Phonons in Ag-BaO Thin Films

Coherent acoustic phonons have been observed in Ag nanoscale particles (NSPs) embedded in BaO thin film by means of the femtosecond time-resolved pump-probe technique. The oscillatory component in the signal corresponds to a very low-frequency acoustic phonon mode of Ag NSPs. The generation of coherent acoustic phonons is attributed to the resonant excitation of localized surface plasmon.

Response time of photoemission of ultrafine particle thin film

The response time of photoemissive materials is required for detecting ultrashort duration laser pulses. In this paper, the response time of photoemission in ultrafine particle thin film is studied, and the transit time spread (TTS) and response time of peak value (tM) are discussed. The photoelectrons response time will increase with increasing energy of photons. If the surface potential barrier of thin film declines, the photoemissive sensitivity or quantum yield will rise, however the response time will also increase, which means that response-time characteristic gets worse. As an example, the response time for Ag-O-Cs thin film is calculated for different cases when photoelectrons, excited in Ag ultrafine particles, travel through Cs2O semiconductor layer to the surface and escape into vacuum. The calculated response time is about 50 fs if this thin film is irradiated by infrared rays of wavelength 1.06 μm.

Research on satellite peak in electron appearance potential spectroscopy

In this paper, satellite peaks of Ti and Ni in electron appearance potential spectroscopy are researched. On the basis of the multiple split theory of atomic energy level and perturbation theory, the relevant energy levels of a satellite peak are obtained and the theoretical curves are given. These theoretical curves are coincident approximately with experimental ones.