Figure 1: Principles of fluorescence quenching and selective sensing.
From: Unambiguous detection of nitrated explosive vapours by fluorescence quenching of dendrimer films
(a) Schematic of the emissive decay of a fluorophore in the absence of an analyte (1) and in the presence of an analyte, where the excited state transfers an electron to the analyte (2), which then decays non-radiatively back to the fluorophore ground state (3). (b) The photoluminescence (PL) response of dendrimer 3 versus time with vapours of each analyte injected independently. It can be seen that the nitro-containing analytes (TNT, DNT=2,4-dinitrotoluene, DMNB and pNT=4-nitrotoluene) quench the PL whilst the vapours of a range of everyday interferents induce a rise of the PL, resulting in a selective response. Note TNT has a vapour pressure of 5 ppb and the strong response to this concentration illustrates the sensitivity of the sensing films. (c) Examples of dendrimers that show selective sensing for nitrated analytes. R=n-propyl. (d) The reduction potentials of dendrimer 3 and the analytes.
