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Diffusion-limited aggregation (DLA) is the process whereby particles undergoing a random walk due to Brownian motion cluster together to form aggregates of such particles. . This theory, proposed by T.A. Witten Jr. and L.M. Sander in 1981, [1] is applicable to aggregation in any system where diffusion is the primary means of transport in the sy
The coupling of chromatography with MS is a well developed chemical analysis strategy dating back from the 1950s. Gas chromatography (GC)–MS was originally introduced in 1952, when A. T. James and A. J. P. Martin were trying to develop tandem separation – mass analysis techniques. [9]
The very facile reaction of Weinreb amides with organolithium and Grignard reagents results from the chelate stabilization in the tetrahedral adduct and, more importantly, the transition state leading to the adduct. The tetrahedral adducts are shown below. Weinreb ketone synthesis and tetrahedral intermediate stability
For example, the image below shows the addition of ethylmagnesium bromide to ethyl sorbate 1 using a copper catalyst with a reversed josiphos (R,S)-(–)-3 ligand. [35] This reaction produced the 1,6-addition product 2 in 0% yield, the 1,6-addition product 3 in approximately 99% yield, and the 1,4-addition product 4 in less than 2% yield.
For example, when methanol solvent is present, the cluster solvent ions would be CH 3 OH 2 + (H 2 O) n (CH 3 OH) m. [2] Fragmentation does not normally occur inside the APCI source. If a fragment ion of a sample is observed, thermal degradation has taken place by the heated nebulizer interface, followed by the ionization of the decomposition ...
In mass spectrometry, direct analysis in real time (DART) is an ion source that produces electronically or vibronically excited-state species from gases such as helium, argon, or nitrogen that ionize atmospheric molecules or dopant molecules. The ions generated from atmospheric or dopant molecules undergo ion-molecule reactions with the sample ...
A good example from solid-state chemistry is the adducts of ethylene or carbon monoxide of CuAlCl 4. The latter is a solid with an extended lattice structure. Upon formation of the adduct, a new extended phase is formed in which the gas molecules are incorporated (inserted) as ligands of the copper atoms within the
The MAssive Cluster Survey (MACS) [1] [2] compiled and characterized a sample of very X-ray luminous (and thus, by inference, massive), distant clusters of galaxies. The sample comprises 124 spectroscopically confirmed clusters at 0.3 < z < 0.7. Candidates were selected from the ROSAT All-Sky Survey data. [3]