In tropospheric chemistry, OH plays a key role. For instance it is essential in converting many trace species from water-insoluble to water-soluble forms, thus assisting in their deposition rate. Due to OH high reactivity, its concentration in the planetary boundary layer (PBL) is very low, at most of the order of 10 6 radicals cm -3. Thus routine measurement of its steady state concentration for comparison with model calculations is non trivial [1,2]. Furthermore, even in the more complete models there still remains some uncertainty as to some of the sources and sinks of OH. Among others it is still somewhat unclear where all the HONO comes from that acts as an early daytime source of OH. Furthermore it is not likely that as yet all the multitude of hydrocarbons that act as non-negligible sinks have been identified.In the present paper we propose a method for investigating the fast kinetics of OH in situ in the atmosphere using a perturbation technique in which high concentration of OH are created by the laser flash photolysis of atmospheric O 3 followed by the reaction of O( 1 D) with H 2 O. Typically we have locally enhanced the hydroxyl radical concentration by 5 orders of magnitude. Thus the OH is easier to detect and its fast disappearance can be followed over a sufficient time period to try to quantify the reaction kinetics. As we shall discuss below, this fast OH kinetics can be reduced to contributions from a small number of reactions, essentially with CO, O 3 , various volatile organic compounds (VOC), NO x and the reaction with OH itself. Consequently if we simultaneously measure the concentrations of CO, O 3 and NO x with the overall OH kinetics, we shall be able to deduce a total hydrocarbon reactivity Σk i [OH] [VOC i ] from the difference between the measured overall OH decay rate and the sum of the reaction rates with CO, O 3 , NO x and OH itself. In a controlled atmosphere with known Σk i [OH] [VOC i ], one can check for possible unknown fast OH reactions. Hence we shall be able to deduce if the fast kinetics of OH in the atmosphere is complete and well understood under condition that the measurements are sufficiently accurate. A final reason for undertaking these measurements of the fast kinetics of OH was that it seemed like a reasonable first choice to test the pump and probe technique for obtaining new information on atmospheric chemistry. Below we describe the experimental method in some detail, and we compare the measured kinetics with those obtained in a model calculation. Experimental data are presented both from controlled atmospheres with known concentrations of chemical constituents, and from the natural PBL. We also mention the possibility of extending these perturbation kinetics measurements from the in situ case to the range resolved remote sensing case, using a DIfferential Absorption Lidar (DIAL) technique. Finally it will be briefly discussed that measurement of Σk i [OH] [VOC i ] could possibly lead to information on local NO x versus VOC limiting of the production of tropos...

CuCl reacts with Na[HB(R3RSpz),] and phosphine (PR,) or isonitrile (CNR) to yield volatile (pyrazolylborate)copper(r) complexes. These compounds were evaluated as MOCVD precursors. Using [ { H B (~Z )~J C U ( P E~~) ]and [ ( H B (~Z )~J C U ( P M~~) ] , thin copper films were grown by thermal metal organic chemical vapor deposition in a low pressure reactor in the temperature range 150-350 "C. Polycrystalline Cu-phases were obtained at temperatures as low as 150 "C. The metallic films were characterized by four-point-probe resistivity measurements, AES, and XPS, as well as AFM and SEM. Selective deposition on metal-seeded surface sites was observed on Pt, Au, Al, and W versus SOz. Anti-selective deposition was found to occur on Pdseeded samples.

Low pressure CVD of copper from its bis-hexafluoroacetylacetonate is studied on oxidized silicon substrates locally seeded with a 2.5 A platinum prenucleation film. Copper is deposited selectively on top of the prenucleation layer from the gaseous metalorganic compound diluted in hydrogen. The selectivity, growth rate and resistivity of the copper deposit strongly depend on the presence of water vapor in the reagent gas mixture.

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