Ionization quenching

Fast concentration and sample injection are considered with the use of a theory of vibrational relaxation. A possibility to reduce a detection limit for trinitrotoluene to 10 g/cnf in less than 1 min is shown. Such a detection limit can by obtained using selective ionization combined with ion drift spectrometry. The time of detection in this case is 1- 3 s. A detection technique based on fluorescent reinforcing polymers, when the target molecules strongly quench fluorescence, holds much promise for developing fast detectors. 

In order to minimize this problem, Ryan (57, 58) combined the pulse techniques of Tal roze (61) with a small continuous repeller field. In this operation, a cluster of ions is formed by a short ionizing pulse and is allowed to react under the influence of a small d.c. field for a certain time. The reaction is then quenched by applying a large (80 volts/cm.)... 

A quenching gas is added to give up electrons to the chamber gas so that inaccuracies are NOT introduced due to ionizations caused by the positive ion. 

A quenching gas is used in order to prevent a secondary pulse due to ionization by the positive ions. 

Plasma excitation would occur on a much longer timescale, while fluorescence from prompt excitation of the 2p level in H could be readily quenched through the ionization of the 2p state with the second laser pulse. 

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