Studies on the response mechanism of thermionic detection to organophosphorus compounds

The response of thermionic/nitrogen-phosphorus detection (TID) to a series of organophosphonate esters has been studied. The response of TID is found to decrease with the increase in the alkyl chain length of the molecules. An attempt has been made to propose the response mechanism of TID for these compounds. The charge carriers accountable for the response do not necessarily arise by combustion of the molecule but by a reaction involving alkali metal and the compound. This has been supported by thermodynamic parameters and molecular descriptors. The mechanism of the reaction that appears to be bimolecular has been explained by steric effects. The study successfully explains the observed change in the response of TID with minor changes in structures of the molecules.