Solute-induced photo-ionization of nonpolar liquids

Transient DC-conductivity measurements of anthracene solutions in cyclohexane have provided evidence for solvent ionization following irradiation with 248nm excimer laser pulses. A mechanism resulting in a cyclohexane cation and an anthracene anion as near neighbors can explain the experimental observations: a high mobility species, 7–8 absorbed photons per solute molecule, intensity dependence, and absence of enhanced hydrogen generation. A photo-ionization apparatus with 20ps time resolution is being developed to observe transient ionization spectroscopically. Such a system may enable observation of solute-induced ionization in solvents having normal mobility cations.