Previously, it has been demonstrated that external electric fields may be used to exert control over chemical reactivity. In this study, the impact of a strong, nonresonant IR field (1064 nm) on the photoisomerization of cis-stilbene is investigated in cyclohexane solution. The design of a suitable reaction vessel for characterization of this effect is presented. The electric field supplied by the pulsed, near-IR radiation (ε l = 4.5 × 10 7 V/cm) enhances the cis → trans photoisomerization yield at the red edge of the absorption spectrum (wavelengths between 337 and 340 nm). Within the microliter focal volume, up to 75% of all cisstilbene molecules undergo isomerization to trans-stilbene in the strong electric-field environment, indicating a significant increase relative to the 35% yield of trans-stilbene under field-free conditions. This result correlates with a 1−3% enhancement in the trans-stilbene concentration throughout the bulk solution. Theoretical analysis suggests that the observed change is the result of dynamic Stark shifting of the ground and first excited states, leading to a significant redshift in cis-stilbene's absorption spectrum. The predicted increase in the absorption cross section in this range of excitation wavelengths is qualitatively consistent with the experimental increase in trans-stilbene production.

The degradation of four model PAH compounds was studied by spraying from a micrometer-sized, grounded nozzle a solution of the PAH in a 1:1 solvent of toluene and isopropanol with a trace of water onto wetted TiO 2 anatase nanoparticles, which were immobilized on an etched stainless-steel support charged at +2 kV. Rubrene was chosen because of its established degradation pathways, and 1-methylpyrene, 2-methylnapththalene, and bis(pyren-1-yl)ethane were chosen because of their molecular structure, containing aromatic islands with short aliphatic groups, representative of a thermally and catalytically processed heavy feed stream. The fractional reaction yield was measured using different support materials and by applying different external voltages to the metal substrate. The optimized method yielding 75% degradation was applied to the other three PAHs, resulting in higher-mass degradation products, apparently formed via radical polymerization.