Trapping time

As with the quadmpole ion trap, ions with a particular m/z ratio can be selected and stored in tlie FT-ICR cell by the resonant ejection of all other ions. Once isolated, the ions can be stored for variable periods of time (even hours) and allowed to react with neutral reagents that are introduced into the trapping cell. In this maimer, the products of bi-molecular reactions can be monitored and, if done as a fiinction of trapping time, it is possible to derive rate constants for the reactions [47]. Collision-induced dissociation can also be perfomied in the FT-ICR cell by tlie isolation and subsequent excitation of the cyclotron frequency of the ions. The extra translational kinetic energy of the ion packet results in energetic collisions between the ions and background... 

Cochran JK, Krishnaswami S (1980) Radium, thorium, uranium and °Pb in deep-sea sediments and sediment pore waters from the north equatorial Pacific. Am J Sci 280 849-889 Cochran JK, Masque P (2003) Short-lived U/Th-series radionuchdes in the ocean tracers for scavenging rates, export fluxes and particle dynamics. Rev Mineral Geochem 52 461-492 Colley S, Thomson J, Newton PP (1995) Detailed °Th, Th and °Pb fluxes recorded by the 1989/90 BQFS sediment trap time-series at 48°N, 20°W. Deep-Sea Res 42(6) 833-848... 

Warscheid, B. Jackson, K. Sutton, C. Fenselau, C. MALDI analysis of Bacilli in spore mixtures by applying a quadrupole ion trap time-of-fhght tandem mass spectrometer. Anal. Chem. 2003, 75, 5608-5617. 

Here (g)T = (e/m)Tf2/(r( + Tt) is called the ballistic mobility and (/t)H = + Tt) is the usual trap-controlled mobility. (q)F is the applicable mobility when the velocity autocorrelation time ( 1) is much less than the trapping time scale in the quasi-free state (fTf l). In the converse limit, (jj)t applies, that is—trapping effectively controls the mobility and a finite mobility results due to random trapping and detrapping even if the quasi-free mobility is infinite (see Eq. 10.8). 

B. Warscheid, K. Jackson, C. Sutton, and C. Fenselau. MALDI Analysis of Bacilli in Spore Mixtures by Applying a Quadrupole Ion Trap Time-of-Flight Tandem Mass Spectrometer. Anal. Chem., 75(2003) 5608-5617. 

For PSI core it has been argued that excitation visits P700 2-3 times on an average prior to being trapped [221]. This conclusion is based on the analysis of time resolved fluorescence trapping times as a linear function of antenna size in terms of the Pearlstein model array treatment (see Sect. 5). A similar conclusion... 

As discussed above (Sect. 6) the RC-trapping time for PSII is extremely long (tj > 300 ps) compared with PSI. This long trapping time is associated with... 

Martin, R. L. Branda, E. L. Analysis of high mass peptides using a novel matrix-assisted laser desorption/ ionisation quadrupole ion trap time-of-flight mass spectrometer. Rapid Commun. Mass Spectrom. 2003, 17, 1358-1365. 

The Michael-type conjugate addition of an alkoxide such as methoxide to an a,p-unsaturated nitrile or aldehyde proceeds in solution quite readily, being complete in 5—10 minutes. In the gas phase however, it was found that reaction (6a) does not occur there is no evidence of the addition product even at the longest trapping times, nor in the unquenched mode. Rather, the sole product observed is due to proton loss from the nitrile, to form a nominal vinyl anion, reaction (6b). 

Quadrupole ion trap—time-of-flight mass spectrometer 2005 QitTof MS 0.9 Syage, 11.3.4... 

The quadrupole ion trap, time-of-flight (QitTofMS) analyzer was first developed by Lubman [12,13] and co-workers. QitTofMS components were first sold commercially by R. M Jordan Company and a full commercial instrument first... 

Quadrupole ion trap, time of flight, mass spectrometer Quantum yield Research and development Reversal electron attachment detection Remote environmental monitoring units Remote explosive scent tracking Radio frequency Ragnar s Homemade Detonators Receiver operator characteristics (a graphical portrayal of Pd and Pfp)... 

Quadrupole Ion trap Time of flight Fourier-transformed ion-cyclotron resonance... 

The charge transport in amorphous selenium (a-Se) and Se-based alloys has been the subject of much interest and research inasmuch as it produces charge-carrier drift mobility and the trapping time (or lifetime) usually termed as the range of the carriers, which determine the xerographic performance of a photoreceptor. The nature of charge transport in a-Se alloys has been extensively studied by the TOF transient photoconductivity technique (see, for example. Refs. [1-5] and references cited). This technique currently attracts considerable scientific interest when researchers try to perform such experiments on high-resistivity solids, particularly on commercially important amorphous semiconductors such as a-Si and on a variety of other materials... 

This parameter was determined from xerographic residual potential in a-Sei- Te monolayer films. As one can see, even with very little Te alloying, there is a considerable rise in both hole and electron deep traps. The relationship between the trapping time and the residual potential has been evaluated by several authors (see, for example. Refs. [12, 15]). It can be seen that once the Te concentration exceeds 12 wt% Te, the residual potential is more than an order of magnitude larger than typical values for pure selenium. 

By lifetime we mean the average time that an excess carrier exists before annihilation by a carrier of the opposite sign. This is as opposed to relaxation time, the average time between collisions, or trapping time, the average time in a band before being trapped. We have used the same symbol, t, to represent both the lifetime and the relaxation time because this symbol... 

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