Improved microphotometry by compensating for fluctuations in the illumination

Behind a beam-splitter in the illuminator, the irradiation of an area conjugated to the object plane is measured by a silicon photodiode and used as a reference signal. Analog division of the photomulitplier signal by this reference acts like stabilizing the light source by a factor greater than 25. A technical realization of the optical and electronical components as well as experimental results are described.     

High coherent bi-chromatic laser with gigahertz splitting produced by the high diffraction orders of acousto-optic modulator used for coherent population trapping experiments

To prepare the coherent population trapping (CPT) states with rubidium and cesium, the commonly used atoms in CPT studies, a coherent bi-chromatic light field with frequency difference of several GHz is a basic requirement. With a 200 MHz center frequency acousto-optic modulator (AOM), we have realized bi-chromatic laser fields with several GHz frequency splits through high diffraction orders. We have experimentally studied the coherence between two frequency components of a bi-chromatic laser beam, which is composed of ±6 orders with frequency split of 3 GHz diffracted from the same laser beam, and the measured residual phase noise is Δφ(2)<0.019 rad(2). The bi-chromatic laser fields were used to prepare CPT states with (85)Rb and (87)Rb atoms, and high contrast CPT signals were obtained. For CPT states preparation, our study result shows that it is a feasible approach to generate the bi-chromatic light field with larger frequency splits through high diffraction orders of AOM.     

Two-dimensional fringe projection for three-dimensional shape measurements by using the CWT phase gradient method

This paper describes an optical measurement technique for the two-dimensional fringe pattern (by introducing the carrier frequencies in two spatial directions x and y) by the continuous wavelet transform (CWT) phase gradient method. Such transforms based on the Morlet and Paul wavelets have been applied to image rows and columns one by one and then added to find the final phase distribution, without using any unwrapping algorithms. This technique is compared with the S-transform phase gradient method. Numerical simulations and actual experiments are carried out to show the validity of this technique for finding the phase distributions.     

转角相位差对双点压力机精度的影响及同步校正方法

曲柄转角相位差是影响闭式双点压力机精度的一个重要因素,对转角相位差影响压力机精度的原理进行分析,并阐述一种实用的同步校正方法.     

粉末X射线衍射法测定氢气还原的气相醛加氢催化剂

采用粉末X射线衍射鉴定氢气还原的气相醛加氢催化剂中晶体物相并应用Scherrer法定量测定铜的晶粒尺寸。其晶体物相鉴定结果为:石墨、氧化锌、铜。采用化学计量学峰形拟合的方法计算铜(111)晶面晶粒尺寸约为10.3 nm,测定数据能够满足气相醛加氢催化剂研发的要求。     

Design and development of a novel nuclear magnetic resonance detection for the gas phase ions by magnetic resonance acceleration technique

Nuclear magnetic resonance (NMR) technique is a well-established powerful tool to study the physical and chemical properties of a wide range of materials. However, presently, NMR applications are essentially limited to materials in the condensed phase. Although magnetic resonance was originally demonstrated in gas phase molecular beam experiments, no application to gas phase molecular ions has yet been demonstrated. Here, we present a novel principle of NMR detection for gas phase ions based on a "magnetic resonance acceleration" technique and describe the design and construction of an apparatus which we are developing. We also present an experimental technique and some results on the formation and manipulation of cold ion packets in a strong magnetic field, which are the key innovations to detect NMR signal using the present method. We expect this novel method to lead new realm for the study of mass-selected gas-phase ions with interesting applications in both fundamental and applied sciences.     

Activation of the SiC surface for vapor phase lubrication by Fe chemical vapor deposition from Fe(CO)5

The feasibility is demonstrated of a new approach to the vapor phase lubrication of ceramics using organophosphorus compounds. The surface of SiC is shown to be unreactive for the decomposition of trimethylphosphite, (CH₃O)₃P, a simple model for organophosphorus vapor phase lubricants such as tricresylphosphate. In order to activate the surface of SiC it has been exposed to Fe(CO)₅ at a temperature of 600 K. Chemical vapor deposition serves as a means of depositing Fe on the SiC surface. The Fe-modified SiC surface is then shown to induce the decomposition of adsorbed (CH₃O)₃P. The mechanism of (CH₃O)₃P decomposition is similar to that observed on Fe(110) surfaces modified by the presence of oxygen. It is initiated by P–O bond cleavage to produce adsorbed methoxy groups, CH₃O_(ad), which then decompose by -hydride elimination resulting in H₂, CO, H₂CO, and CH₃OH desorption. It is suggested that chemical vapor deposition of metals using high vapor pressure metal-containing compounds such as Fe(CO)₅ can serve as a mechanism for continuous, in situ activation of ceramic surfaces for vapor phase lubrication in high temperature engines.     

A facility for studying the spatial and temporal characteristics of a plume produced by interaction of high-power CO<Subscript>2</Subscript> laser pulses with a solid-state target in various gas environments

An experimental facility for studying the kinetics of molecular association formation from atoms produced by evaporation of the target material by powerful CO₂ laser pulses is described. First experimental results are presented for the spectral and spatial-temporal characteristics of the spread of Al atoms produced in interactions of laser radiation with aluminum oxide Al₂O₃, followed by AlO formation in various low-pressure (0.1–0.3 Torr) atmospheres. Images of structurally similar forms condensed on a glass surface have been observed with an atomic-force microscope.