High resolution X-ray computed tomographic (CT) images of chondrites and a chondrule

In order to study internal textures of meteorites, images were obtained by X-ray computer tomography (CT). This combined high resolution X-ray radiography and computer tomography system belongs to the so-called third generation type with a micro-focus X-ray source and a linear CCD detector with 2048 elements. This allows a spacial resolution of a few μm in the images. Samples examined include the Moorabie meteorite (L3), Allende meteorite (CV3), and a chondrule removed from Allende meteorite. In images, Fe-Ni alloy, troilite, and silicates can be distinguished clearly, and chondrules can be resolved from their Fe-rich rims in Moorabie meteorite. In Allende Fe-Ni alloy, pentlandite, and silicates can be distinguished, and chondrules, CAI\u27s, and matrix can be recognized. Many euhedral crystals, probably olivine and/or pyroxene, were identified in a chondrule, suggesting that the chondrule has a porphyritic texture. In addition to minerals or their assemblages, holes can be identified by the X-ray CT method and were found in chondrules in Allende

Miyake H: Adsorption promotion of Ag nanoparticle using cationic surfactants and polyelectrolytes for electroless Cu plating catalysts. J Electrochem Soc 2010, 157:D211. doi:10.1186/1556-276X-6-483 Cite this article as: Wang et al.: Self-assembled monolay

Ag nanoparticles were adsorbed onto epoxy and fluorine-doped tin oxide ͑FTO͒ glass substrates by dipping them into a Ag nanoparticle colloidal solution to catalyze the substrate for electroless Cu plating. Before the Ag nanoparticle adsorption, the substrates were conditioned with either a cationic surfactant, stearyltrimethylammonium chloride ͑STAC͒, or a cationic polyelectrolyte, poly͑diallyldimethylammonium chloride͒ ͑PDDA͒, both having quaternary amine headgroups. The adsorbed Ag nanoparticles catalyzed the HCHO oxidation reaction, thereby allowing the electroless Cu deposition reaction to start. For both the epoxy and the FTO glass substrates, conditioning with the concentrated PDDA solution having a 100 ϫ 10 −3 mol L −1 quaternary amine concentration was the most effective in producing the largest amounts of Ag nanoparticles to be adsorbed and in providing the fastest initial deposition rate of the electroless Cu plating. When the diluted conditioners were used, a comparison between the diluted STAC and PDDA showed that STAC was the more effective conditioner for the epoxy substrates, while PDDA was more effective for the FTO glass substrates. The effectiveness of STAC was attributed to the strong hydrophobic interaction with the epoxy substrate surface. However, the effectiveness of PDDA was attributed to the strong electrostatic interaction with the FTO glass surface. © 2010 The Electrochemical Society. ͓DOI: 10.1149/1.3306025͔ All rights reserved. Electroless plating on polymer substrates is widely used in the automotive and electronics industries. 1 In particular, electroless Cu plating on epoxy or polyimide substrates is a crucial process during printed wiring board ͑PWB͒ manufacturing. 2 Many stages during the pretreatment for the electroless plating are required, such as surface roughening, substrate conditioning, catalyzing, and accelerating. The catalyzing process is essential to initiate the electroless plating. Polymer substrates are usually catalyzed by the adsorption of Pd/Sn mixed colloids from a solution. 3 The Pd/Sn mixed colloidal catalysts, however, do not appreciably adsorb on the epoxy surface; 4 therefore, a conditioning process for the substrates is needed. Luke 5 pointed out that cationic surfactants neutralize the negative charge of the epoxy surface and promote the adsorption of the negatively charged Pd/Sn mixed colloidal catalysts. It has also been reported that cationic polyelectrolytes are effective as substrate conditioners for introducing a positive surface charge. 7 For example, residual Pd beneath the photoresist permits the electroless Cu to be deposited between the circuit lines and causes an insulation decrease and short circuits. 7-9 In a previous paper, 10,14 Because these shells give a negative surface charge to the Ag nanoparticles, 10,14 the substrate conditioning to introduce the positive surface charge is needed for the promotion of the electrostatic adsorption of the Ag nanoparticles. The aim of this study is to increase the adsorbed amounts of the Ag nanoparticles and to obtain a higher catalytic activity for the electroless Cu plating. We describe the substrate conditioning processes to promote the Ag nanoparticle adsorption using a cationic polyelectrolyte, and we discuss the adsorption promotion mechanisms compared to those using cationic surfactants. The cationic surfactant conditioner used in this study is stearyltrimethylammonium chloride ͑STAC͒, which is an effective conditioner for the epoxy substrates. 10 As the polyelectrolyte conditioner, poly͑dial-lyldimethylammonium chloride͒ ͑PDDA͒ having a linear alkyl main chain and a quaternary amine group in the side chains was used. Our preliminary study has shown that PDDA promotes the Ag nanoparticle adsorption onto a glass substrate. 15 Experimental Preparation of Ag nanoparticle colloidal solution.-Ag nanoparticle colloidal solutions were prepared by reducing Ag + ions with the Sn͑II͒-citrate complex, as described in the previous paper. 10 Reagent grade chemicals of SnSO 4 , trisodium citrate dihydrate, and AgNO 3 were used as-received. The water was purified by a Millipore Milli-RX12 Plus system. The preparation procedure of the Ag nanoparticle colloidal solutions was simply the mixing of a volume of a 1 mol L −1 AgNO 3 solution with a Sn͑II͒-citrate complex solution. The Sn͑II͒-citrate complex solution was simply prepared by mixing a SnSO 4 solution and a trisodium citrate solution. The resulting Ag nanoparticle colloidal solutions contained 0.01 mol L −1 Ag, 0.1 mol L −1 total Sn, and 0.2 mol L −1 total citrate. The pH of the solution was not adjusted and was 5.1. Adsorption of Ag nanoparticles onto the epoxy substrate.-Cuclad epoxy boards ͑FR-4, Sunhayato͒, the Cu layers of which were chemically removed by 0.9 mol L −1 ammonium peroxodisulfate solution at 50°C, were used as the substrates. As the conditioning process to promote the adsorption of the Ag nanoparticles, the substrates were dipped into an STAC ͓CH 3 ͑CH 2 ͒ 17 NH 4 Cl, Nakalai Tesque͔ solution at 50°C or a PDDA ͑20 mass % in water, M