نتایج جستجو برای: negative ion
تعداد نتایج: 728793 فیلتر نتایج به سال:
The use of Accurate-Mass Q-TOF LC/MS and MS/MS, in both positive and negative electrospray ionization (ESI) modes, was evaluated for the identification of sucralose in water. Response and fragmentation pathways were investigated. Sucralose responded well using Q-TOF LC/MS in either the positive or negative ion ESI modes. The overall signal intensity obtained in positive ion mode was approximate...
This is a study of the negative ion chemistry in the mesosphere above Troms using a number of EISCAT observations of high energy proton precipitation events during the last solar maximum, and in particular around sunset on 23 October, 1989. In these conditions it is possible to look at the relative importance of the various photodetachment and photodissociation processes controlling the concent...
Different alkali metal atoms are observed to donate electrons to CF(3)Br molecules that are oriented in space. For collision energies high enough to overcome the Coulomb attraction, a positive ion/negative ion pair is observed and mass-analyzed using coincident time-of-flight mass spectroscopy. The alkali metal cation and various negative ions are observed. The most abundant negative ion is the...
A spectrally selective imaging system has been installed in the RF negative ion source in the International Thermonuclear Experimental Reactor-relevant negative ion beam test facility ELISE (Extraction from a Large Ion Source Experiment) to investigate distribution of hydrogen Balmer-α emission (Hα) close to the production surface of hydrogen negative ion. We selected a GigE vision camera coupl...
Positive ion mode collision-activated dissociation tandem mass spectrometry (CAD MS/MS) of O-sulfopeptides precludes determination of sulfonated sites due to facile proton-driven loss of the highly labile sulfonate groups. A previously proposed method for localizing peptide and protein O-sulfonation involves derivatization of nonsulfonated tyrosines followed by positive ion CAD MS/MS of the cor...
The effects of the weak magnetic field on the negative ion ( ) extraction in a negative ion source have been studied by means of a two-dimensional electrostatic particle simulation. A particle-in-cell (PIC) model is used which simulates the motion of the charged particles in their self-consistent electric field. Since most electrons are magnetized by the weak magnetic field, it is shown that mo...
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