Research Interests

Phosphorus in its white elemental form reacts spontaneously with air to produce an intense white-green chemiluminescent glow. The oxidation proceeds via a complex chain reaction which has been the subject of many studies since the isolation of phosphorus in 1669. The identity of the emitting species has been the subject of considerable controversy, but is now known to be an excited electronic state of the PO₂ radical.

In Cambridge, we have used infra-red diode laser absorption spectroscopy to directly probe the transient species generated by the chemiluminescent reaction between oxygen atoms and P₄ vapour. The short-lived molecules are produced in a fast flow system incorporated in a multiple pass White cell, with absorption pathlengths of up to 40m. By carefully controlling the reaction conditions, new infra-red spectra of PO, PO₂ and P₂O have been detected.

The complexity of the oxidation chain reaction opens the door to a range of novel species. Recently, we have observed the PNO molecule for the first time in the gas phase by addition of NO to the chemiluminescent region. This molecule is found to have a linear structure, analogous to its counterparts P₂O and N₂O. Currently, we are exploring novel species formed when Cl₂ is added to the reacting gas region, in particular the OPCl molecule.