Radical-trapping device

With the site-selective hole injection and the hole trapping device established, the efficiency of the hole transport between the hole donor and acceptor, especially with respect to the distance and sequence dependence, were examined. Our experiments showed that hole transport between two guanines was extremely inefficient when the intervening sequence consisted of more than 5 A-T base pairs [1]. Hole injection into the DNA n-stack using photoexcited dCNBPU was accompanied by the formation of dCNBPU anion radical. Therefore, hole transport would always compete with the back electron transfer (BET). To minimize the effect of BET, we opted for hole transport between G triplets, that are still lower in oxidation potential than G doublet. With this experimental system, we researched the effect of the bridging sequence between two G triplets on the efficiency of hole transport [2]. 

Xenon difluoride reacted with various carboxylic acids, and the type of transformation depends on the structure of the organic molecules35-39. The reaction with primary carboxylic acids involves free-radical intermediates. 6-Hexenoic acid was used as a free-radical clock device in which a A abs of 1.1 x 106 M-1s-1 at 25 °C was determined, while the alkyl radical was also spin-trapped to give an ESR signal37. The primary free radical was trapped by internal cyclization, and (fluoromethyl) cyclopentane in 25% yield was formed, while 6-fluoro-l-hexene could be formed from a radical or ionic intermediate, but 1-fluo-rocycloclohexane was not observed as a product (Scheme 42). 

Due to its radically different design, the latest hybrid linear ion trap FTMS instrument, the LTQ-Orbitrap (Fig. 5.6), does not suffer from the time-of-flight effect. In this instrument, the superconducting magnet and the ICR cell are replaced by an electrostatic trap (C-trap) and so distances traveled by the ions from one MS device to the other are much smaller in addition a radically different ion transfer mechanism virtually eliminates any possibility for a time-of-flight effect (Makarov,... 

Co-deposition entails the formation of hydrogenated carbon layers via the redeposition of eroded C atoms and C-containing molecules/radicals in combination with the fuel H, on both plasma facing and out of line-of-sight surfaces in the device. Such layers have been observed to exceed tens of tm (e.g., in TFTR [26,27]), much thicker than the ion-implantation region, which only extends tens of nm. In addition, the co-deposited layer does not appear to have a limit to its thickness. The H/C ratio in the co-deposited layers is similar to that seen in the implantation zone, viz, 0.4 at room temperature. Based on experience with current tokamaks [7, 28, 29] and predictions for ITER [3], most of the T in an ITER-type machine is expected to be trapped in co-deposits. Consequently, the removal of such layers has recently become a high priority issue. This will be addressed in Sect. 10.4. 

Fig. 4.62. hQh-ICR hybrid instrumentation. This instrument is equipped with an ESI-to-MALDI switchable ion source that makes use of a two-stage ion funnel (d), ) to focus ions into a RF hexapole ion guide (h, ). The ions then pass a quadmpole ( ) that may either be mn as band pass (q) or as mass-selective device (Q) and then reach a multifunctional RF hexapole ion trap (h, ) where they can be i) accumulated, ii) coUisionally activated, or Hi) reacted with radical anions from the NCI source to effect ETD as required. For mass analysis the ions are then guided via an RF-oiily hexapole ( ) into the ICR cell ( ) where a hollow cathode ( ) is attached for BCD. Schematic of Bruker Solarix instrument series by courtesy of Bruker Daltonik, Bremen. 

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