Measurement of Heating Rates in a Microscopic Surface-Electrode Ion Trap

We report measurement of heating rates of 40 Ca＋ ions confined in our home-made microscopic surface-electrode trap by a Doppler recooling method. The ions are trapped with approximately 800 μm above the surface, and are subjected to heating due to various noises in the trap. There are 3-5 ions involved to measure the heating rates precisely and efficiently. We show the heating rates in variance with the number and the position of the ions as well as the radio-frequency power, which are helpful for understanding the trap imperfection.

OBSERVATION OF EPITAXIAL OVERLAYER OF METALS AT ATOMIC LEVEL

Observation of epitaxial overlayer of metals at atomic level has been successfully observed in field ion microscope with 5 ns pulsed-laser heating.The condition of superlattice layer growth depends on the surface free energy and the lattice misfit.Many defects,such as vacancies,va- cancy clusters,voids,dislocations and twins are produced during epitaxial growth because of the lattice misfit even though the condition of surface free energy is satisfied.Alloying is ob- served to occur on the surface of the metal during the epitaxial growth.Diffusion is probably via the exchange mechanism.

PRECIPITATION HARDENING OF ELINVAR ALLOY

The microstructural evolution and precipitation hardening of an Elinvar alloy doped with Ti and Al during isothermal aging at 700℃ have been investigated by atom probe field ion microscopy and microhardness measurements.The γ′ precipiates are spherical and coherent with the matrix.The chemical composition of the precipitates are(Ni_(0.53)Fe_(0.47)_3 (Ti_(0.(?))Al_(0.4)). During aging,a Lifshitz-Wagner type dissolution and coarsening reaction of the precipitates has been observed,The hardness of the material varies with the aging time and reaches maxi- mum when the average diameter of the precipitates was about 11 nm.

Ion Photon Emission Microscope for Single Event Effect Testing in CIAE

Ion photon emission microscopy （IPEM） is a new ion-induced emission microscopy. It employs a broad ion beam with high energy and low fluence rate impinging on a sample. The position of a single ion is detected by an optical system with objective lens, prism, microscope tube and charge coupled device （CCD）. A thin ZnS film doped with Ag ions is used as a luminescent material. Generation efficiency and transmission efficiency of photons in the ZnS（Ag） film created by irradiated Cl ions are calculated. A single Cl ion optical microscopic image is observed by high quantum efficiency CCD. The resolution of a single Cl ion given in this IPEM system is 6μm. Several factors influencing the resolution are discussed. A silicon diode is used to collect the electrical signals caused by the incident ions. Effective and accidental coincidence of optical images and electronic signals are illustrated. A two-dimensional map of single event effect is drawn out according to the data of effective coincidence.

Study of the Structure of Oxide Interface in the Pt-Rh Alloy by AP-FIM

This paper reports the study of structure of oxide interface in Pt-Rh alloy by atom probe field ion microscope (AP-FIM) which is well suited for the study of atom distribution with atomic scale at the surface and interface of alloy. AP depth profiles show that oxide interface exist in the Pt-Rh alloy which consists of PtO, RhO, PtO2 and RhO2. The mechanism of oxidation of the alloy is considered as that first oxygen molecules adsorbed on-to the surface of alloy then dissociate into oxygen atoms (O2&rarr2O). Consequently oxygen atoms diffuse into interior through grain boundary forming oxide (M+O&rarrMO). When the concentration of oxygen continuously increases the dioxide (MO+O&rarrMO2) forms.

Micro-pore Structure and Gas Accumulation Characteristics of Shale in the Longmaxi Formation, Northwest Guizhou

For further study on characteristics of micro-pores in the marine shale reservoirs in Northwest Guizhou,shale samples in the Lower Silurian Longmaxi Formation were selected to investigate effect of micro-pores on the characteristics of gas accumulation in shales,through methods of the argon broad ion beam-field emission scanning electron microscope and the nitrogen adsorption/desorption,analysis on the characteristics of micro-pores and related geochemical analysis.Results show that there are seven types of pores in the Longmaxi Formation shale,including interparticle pores,intraparticle pores,intercrystalline pores,dissolution pores,fossil pores,organic pores,and microfractures,among which the interparticle pores and organic pores are best developed.According to the nitrogen adsorption/desorption curves,the pore structures can be classified into three types,including the cylindrical pores with both opening ends,narrow parallel-plate pores and tapered parallel-plate pores with four opening sides.Diameter of micro-pores ranges from 2 to 64 nm,mainly at 2-6 nm.The diameter of micro-pores(less than 2 nm)ranges from 0.4 to 1.8 nm,The micro-pores with a diameter of 0.4-1.0 nm contribute most to the pore volume.Pore volume is dominated by meso-pores(2-50 nm)with a proportion of 83.1%.The micro-pores and meso-pores make major contribution to the specific surface area of pores with proportions of 20.1%and 79.3%,respectively.The total organic carbon(TOC)is the major factor controlling development of nanopores.Different pore types have different characteristics of gas occurrence and migration,indicating that nanopores provide favorable conditions for the occurrence and microscopic migration of gas in shales.