Characterizing and optimizing a laser-desorption molecular beam source

The design and characterization of a new laser-desorption molecular beam source, tailored for use in x-ray-free-electron-laser and ultrashort-pulse-laser imaging experiments, is presented. It consists of a single mechanical unit containing all source components, including the molecular-beam valve, the sample, and the fiber-coupled desorption laser, which is movable in five axes, as required for experiments at central facilities. Utilizing strong-field ionization, we characterize the produced molecular beam and evaluate the influence of desorption laser pulse energy, relative timing of valve opening and desorption laser, sample bar height, and which part of the molecular packet is probed on the sample properties. Strong-field ionization acts as a universal probe and allows to detect all species present in the molecular beam, and hence enables us to analyze the purity of the produced molecular beam, including molecular fragments. We present optimized experimental parameters for the production of the purest molecular beam, containing the highest yield of intact parent ions, which we find to be very sensitive to the placement of the desorbed-molecules plume within the supersonic expansion

Duality relations between spatial birth-death processes and diffusions in Hilbert space

Spatially dependent birth-death processes can be modelled by kinetic models such as the BBGKY hierarchy. Diffusion in infinite dimensional systems can be modelled with Brownian motion in Hilbert space. In this work Doi field theoretic formalism is utilised to establish dualities between these classes of processes. This enables path integral methods to calculate expectations of duality functions. These are exemplified with models ranging from stochastic cable signalling to jump-diffusion processes

Computer identification of white blood cells

The hardware and software problems for an effective image processing system are described, with a real time high speed system solution as the goal. The discriminating power of the algorithms has been tested in a simulation made on the PIQUANT film scanner and is between 67 and 92% depending on the definition of accuracy. The results are expected to be of value to firms designing and building commercial equipment and to prospective purchasers of it

Characteristics of American coals in relation to their conversion into clean energy fuels. Quarterly technical progress report, January-March 1978

Twenty-one coal samples have been added to the Penn State/ERDA Coal Sample Bank. Ninety-six sets of analytical data and 114 coal samples were provided upon request to other agencies engaged in coal research. Mass spectrometer and reactor systems have been used successfully in measuring the amount of vaporization (and pyrolysis) products of hydrocarbons in low concentrations in a helium carrier gas. Research has shown, using small angle x-ray scattering, that the pore structure of a char is a function of the rank of the parent coal and maximum heat treatment temperature. Carbon deposition on chars from the cracking of methane decreases subsequent reactivity of the char to air. The decrease in reactivity appears to be due to a decrease in active surface area and deactivation of catalytic impurities. Experimental results previously obtained concerning the combustion of char and anthracite have been analyzed with respect to a simple theory of radiative flame propagation and the computer model has been used to investigate the effects of fuel particle density variations. In the study of the combustion characteristics of coal-oil-water emulsions, furnace efficiency peaked at about 5% coal addition, at 10% water, and 20% excess air

Computer identification of white blood cells

The hardware and software problems for an effective image processing system are described, with a real time high speed system solution as the goal. The discriminating power of the algorithms has been tested in a simulation made on the PIQUANT film scanner and is between 67 and 92% depending on the definition of accuracy. The results are expected to be of value to firms designing and building commercial equipment and to prospective purchasers of it

Characteristics of American coals in relation to their conversion into clean energy fuels. Quarterly technical progress report, April--June 1977. [Coal-oil-water slurries]

One hundred and twelve coal samples have been added to the Penn State/ERDA Coal Sample Bank. One hundred and sixty-one sets of analytical data and 45 coal samples were provided upon request to other agencies engaged in coal research. Construction of the pressurized laminar flow isothermal reactor is complete and delivery has been made. Rapid heating of the precursor coal has been found to enhance char reactivity in the case of a North Dakota lignite. The differential scanning calorimetry technique has been used to determine the heat of chemisorption of oxygen on an activated Saran carbon