Trapping device experiments, isolating

A representative example for the information extracted from a TRMC experiment is the work of Prins et al. [141] on the electron and hole dynamics on isolated chains of solution-processable poly(thienylenevinylene) (PTV) derivatives in dilute solution. The mobility of both electrons and holes as well as the kinetics of their bimolecular recombination have been monitored by a 34-GHz microwave field. It was found that at room temperature both electrons and holes have high intrachain mobilities of fi = 0.23 0.04 cm A s and = 0.38 0.02 cm / V s V The electrons become trapped at defects or impurities within 4 ps while no trapping was observed for holes. The essential results are (1) that the trap-free mobilities of electrons and holes are comparable and (2) that the intra-chain hole mobility in PTV is about three orders of magnitude larger than the macroscopic hole mobility measured in PTV devices [142]. This proves that the mobilities inferred from ToF and FET experiments are limited by inter-chain hopping, in addition to possible trapping events. It also confirms the notion that there is no reason why electron and hole mobilities should be principally different. The fact... 

An analyst performing many off-line pyrolyses or reactant gas studies will probably select an automatic means of isolating the pyrolysis end of the experiment from the analytical. This is typically done by employing a valve in a heated oven to place the collection device alternately on-line with the pyrolyzer or with the analytical device. Commercial systems are available that incorporate this valve in a programmable controller to automate the process, as well as in manually operated modes. The pyrolysis chamber carrier gas is directed through the valve to the trap. 

In addition to an efficient scan operation mode, ion trap mass spectrometers offer possibilities of MS" experiments. With the selective removal of ions from the trap, storage of a precursor ion of interest and its resonant activation,collision-induced dissociation (CID) is obtained, giving rise to product ion spectra that provide information comparable to triple quadrupole MS/MS experiments. Moreover, product ions obtained from CID can be further subjected to isolation and dissociation, which enables MS" analyses and, thus, more insights into structural features of analytes and gas-phase reaction and degradation processes. However, also limitations of ion trap tandem mass spectrometry were reported primarily resulting from the low-mass cut-off in MS" experiments, which were circumvented for instance by combining in-space dissociation devices with ion trap mass analyzers. 

---