Application of the Landau-Zener Model and Fermi's Golden Rule to Estimate Triplet Quantum Yield for Organic Molecules

TL;DRAbstract

In order to aid in the development of computational methods to guide environmental chemistry, methods for estimating triplet quantum yield (TQY) were applied to 3 test molecules: benzene, aniline and acetophenone. The Landau-Zener model was implemented with an Arrhenius type rate equation to determine relative intersystem crossing (ISC) and internal conversion (IC) rates. Preliminary calculations using this approach considering only the S0, S1and T1 states gave estimates of TQY at 0.56 for aniline (experimental: 0.9)2 and 1.00 for benzene (experimental 0.15).2 Although this estimate for aniline was deemed within acceptable range for predictive purposes, the estimate for benzene incorrectly estimated IC rate to be negligible relative to ISC rate. Due to long calculation times for the calculations required for the Landau-Zener model, as well as its unreliable predictions in this implementation, a second method was pursued using Fermi’s Golden Rule (FGR). TQY predictions were not obtained

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