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961.
Aerosol optical tweezers coupled with Raman spectroscopy can allow the detailed investigation of aerosol dynamics. We describe here measurements of the evolving size, composition, and phase of single aqueous aerosol droplets containing the surfactant sodium dodecyl sulfate and the inorganic salt sodium chloride. Not only can the evolving wet particle size be probed with nanometer accuracy, but we show that the transition to a metastable microgel particle can be followed, demonstrating that optical tweezers can be used to manipulate both spherical and non-spherical aerosol particles. Further, through the simultaneous manipulation and characterization of two aerosol droplets of different composition in two parallel optical traps, the phase behavior of a surfactant-doped particle and a surfactant-free droplet can be compared directly in situ. We also illustrate that the manipulation of two microgel particles can allow studies of the coagulation and interaction of two solid particles. Finally, we demonstrate that such parallel measurements can permit highly accurate comparative measurements of the evolving wet particle size of a surfactant-doped droplet with a surfactant-free droplet. 相似文献
962.
The partitioning of an immiscible and volatile organic component between the gas and aqueous condensed phases of an aerosol is investigated using optical tweezers. Specifically, the phase segregation of immiscible decane and aqueous components within a single liquid aerosol droplet is characterized by brightfield microscopy and by spontaneous and stimulated Raman scattering. The internally mixed phases are observed to adopt equilibrium geometries that are consistent with predictions based on surface energies and interfacial tensions and the volume fractions of the two immiscible phases. In the limit of low organic volume fraction, the stimulated Raman scattering signature is consistent with the formation of a thin film or lens of the organic component on the surface of an aqueous droplet. By comparing the nonlinear spectroscopic signature with Mie scattering predictions for a core-shell structure, the thickness of the organic layer can be estimated with nanometer accuracy. Time-dependent measurements allow the evolving partitioning of the volatile organic component between the condensed and vapor phases to be investigated. 相似文献
963.
Szanyi J Kwak JH Kim do H Wang X Hanson J Chimentao RJ Peden CH 《Chemical communications (Cambridge, England)》2007,(9):984-986
Exposure of NO(2)-saturated BaO/gamma-Al(2)O(3) NO(x) storage materials to H(2)O vapour results in the conversion of surface nitrates to Ba(NO(3))(2) crystallites, causing dramatic morphological changes in the Ba-containing phase, demonstrating a role for water in affecting the NO(x) storage/reduction properties of these materials. 相似文献
964.
The conversion of primary amines into secondary amines has been achieved using alcohols as the alkylating agent, catalysed by [Ru(p-cymene)Cl2]2 and a bidentate phosphine ligand. 相似文献
965.
Yoon ZS Noh SB Cho DG Sessler JL Kim D 《Chemical communications (Cambridge, England)》2007,(23):2378-2380
Using the bidirectional NICS scan method in conjunction with two-photon absorption (TPA) measurements, it has proved possible to determine the relationship between pi-conjugation and aromaticity in two structurally related expanded porphyrin systems, sapphyrin and inverted sapphyrin, and establish that differences in these defining factors depend on the presence or absence of a key sp3 hybrid molecular orbital within the macrocyclic periphery. 相似文献
966.
Steed JW Goeta AE Lipkowski J Swierczynski D Panteleon V Handa S 《Chemical communications (Cambridge, England)》2007,(8):813-815
Templation of a daughter phase by a parent crystal results from an equilibrating mixture of two very different copper(ii) N,N',N'-trimethyltriazacyclononane complexes. 相似文献
967.
Shannon J Bernier D Rawson D Woodward S 《Chemical communications (Cambridge, England)》2007,(38):3945-3947
Addition of AlMe3 to commercial THF solutions of RZnX (R = aryl, functionalised aryl, vinyl; X = Br, I) simultaneously promotes Schlenk equilibria (leading to competent nucleophiles) and the formation of an Al-Zn-ligand catalyst delivering 80-90% ee for Ar(1)CH(OH)Ar(2) formation from aldehydes. 相似文献
968.
Torres T Gouloumis A Sanchez-Garcia D Jayawickramarajah J Seitz W Guldi DM Sessler JL 《Chemical communications (Cambridge, England)》2007,(3):292-294
A new non-covalent electron transfer model system, based on the use of cytidine-guanosine hydrogen bonding interactions, is described that incorporates a phthalocyanine photodonor and a C60 fullerene acceptor. 相似文献
969.
DFT computed transition states quantitatively explain the surprising stereochemical outcome of unsubstituted enolborinates in diastereoselective and enantioselective boron aldol reactions. 相似文献
970.
Selby JD Manley CD Feliz M Schwarz AD Clot E Mountford P 《Chemical communications (Cambridge, England)》2007,(46):4937-4939
Two broadly applicable strategies for extending the available ligand platforms of the virtually unexplored terminal Ti=N-NR2 functional group are described, along with the highly selective room temperature insertion of alkynes into the N-N bond of Ti{MeN(CH2CH2NSiMe3)2}(NNPh2)(py) and the catalytic cis-diamination of PhC[triple bond]CMe by diphenylhydrazine. 相似文献