Fringe field quantification in an LDV probe volume by use of a magnified image

The magnified cross-section of the LDV probe volume fringe field created on a far screen (image plane) with an imaging lens is examined both analytically and experimentally. It is shown that measurements of the image plane fringe field can be used to quantitatively determine the fringe field existing within the probe volume. Because the fringe spacing in the magnified image is more accessible experimentally, both longitudinal- and lateral-coordinate variations in fringe spacing can be determined, permitting a complete mapping of the fringe field. The detailed knowledge of the fringe field thus obtained allows beam quality, alignment, and fringe uniformity to be evaluated with greater precision than is possible with other techniques.The authors would like to acknowledge C. F. Edwards and R. L. Schmitt for the loan of the beam profiler and for many helpful discussions. This work was performed at the Combustion Research Facility, Sandia National Laboratories, and was supported by the U.S. Department of Energy, Office of Industrial Technologies, Advanced Industrial Concepts Division.     

Scanning tunnelling microscopic images of the surface ordering of the liquid crystal 4-n-octyl-4'-cyanobiphenyl

Images of the surface ordering of 4-n-octyl-4'-cyanobiphenyl, a room temperature smectic liquid crystal deposited upon graphite, have been obtained by scanning tunnelling microscopy. The microscope was operated in air using the constant-current mode. Under certain tunnelling conditions it has been possible to resolve both the aliphatic and aromatic parts of the molecule, and to observe individual benzene rings. Two previously unreported conformations have been observed: an overlapping bilayer structure with spacing 3.7 nm, and a monolayer structure with spacing 2.4 nm. The latter structure may represent the first visual evidence for a surface polar ordered structure.     

Ti－Si沸石的催化氧化性能Ⅱ．环己醇的氧化及环己酮的肟化

Ｔｉ－Ｓｉ沸石的催化氧化性能Ⅱ．环己醇的氧化及环己酮的肟化夏清华，王公慰，应慕良，郑禄彬（中国科学院大连化学物理研究所，大连１１６０１２）关键词Ｔｉ－Ｓｉ沸石催化剂，Ｈ_２Ｏ_２氧化剂，环己醇氧化，环己酮肟化．１．前言环己酮肟是生产ε－己内酰胺的关键中...     

Tertiary Education Faculty Planning: An Application of a Substantially New Direct Control Model

In this paper, an absorbing Markov chain representing the stocks and flows of undergraduate students in a tertiary education faculty is established.In order to assist faculty planners in achieving specific goals, a direct control model in fixed time is developed that allows a partial specification of the distribution of students within the system based on the concept of stated ratios. The attainment and maintenance of this objective, together with a given system size for each planning period, is attempted through recruitment control, as this is the most appropriate control mechanism in an educational institution. The unique specification of the distributional objective makes for considerable ease of planning.The development of a useful sensitivity analysis modus operandi, along with a new efficient solution algorithm to the direct control model, further enhances its applicability for faculty planning.     

Pre-resonance Raman intensity studies of TCNQ and TCNQ−

Pre-resonance Raman spectra have been obtained for TCNQ and LiTCNQ in acetonitrile solution using an Ar⁺—Kr⁺ laser and a tunable rhodamine 6G dye laser. Using the theory of Albrecht and Hutley, we have calculated frequency factors for the intensity variations for several symmetric vibrational modes of each molecule. The observed spectra for TCNQ and LiTCNQ with violet, blue, and green excitation give evidence for B-type resonance enhancement due to vibronic mixing between at least two violet and ultraviolet transitions. The Raman spectra for LiTCNQ with yellow, orange, and red excitation show A-type enhancement due to a single electronic excitation in the near infrared.     

用于气/固吸附的微分吸附热测定装置

本文介绍了一套吸附热测定装置, 它是对法国SETARAM高温量热计进行了适当变动后而建成的。用它可以测定在室温～800 K范围内气/固吸附的微分吸附热。在实验过程中, 吸附量是用光标微压计进行测量。用电标定法代替标准物质法来测定该装置的热定量因子, 这更适合于在恒温条件下的吸附热测定。用这套装置测定了吡啶在HY分子筛上于不同温度下的吸附热。