Explosive vapour sensing with organic and hybrid semiconductors

Abstract

This thesis presents research that aims to develop organic semiconductor sensors for trace vapours of explosives, and to solve some of the hurdles faced in these sensors in the field. This research combines traditional laboratory based investigations of new sensor materials, and the development of methodologies to apply the sensors for humanitarian demining and potential new applications for counter terrorism and forensics.

Molecular imprinted sol gels are developed to discriminate against distractants, such as pesticides. These show a strong discrimination between the target molecule DNT and the distractant dinoseb. Alternative ways to deposit the sensing layer and increase sensitivity were tested including mats of polymer nanofibres and free standing membranes. Thin films of hybrid perovskites were studied as an alternative fluorescence quenching sensor material, including the effect of hybrid perovskite crystal dimensionality on the sensing process, it is shown that perovskite nanocrystals are highly sensitive to 2,4-DNT vapours.

A major problem facing any explosive vapour sensing system is the collection of explosive vapours for analysis. One potential solution is the Remote Explosive Scent Tracing (REST) method in which air samples are drawn through a filter, and the filter tested for the presence of explosive residues. The fluorinated polymer Aflas 200-pR was successfully demonstrated as a preconcentrator for explosive vapours in REST sampling. The preconcentration method was further developed and trialled in the field to maximise explosive residues collected post-blast in a forensic counter terrorism application, and to maximise the amount of explosives collected from beehives placed on a minefield in the NATO SPS project Biological Methods (Bees) for the detection of explosives (Bee4exp).

Date of Award	21 Jun 2022
Original language	English
Awarding Institution	University of St Andrews
Supervisor	Graham Turnbull (Supervisor) & Ifor David William Samuel (Supervisor)