The dominant nature of Herzberg-Teller terms in the photophysical description of naphthalene compared to anthracene and tetracene

Abstract

The first order and second order corrected photoluminescence quantum yields are computed and compared to experiment for naphthalene in this manuscript discussing negative results. Results for anthracene and tetracene are recalled from previous work [J. Chem. Phys. 155, 054108 (2021)], and the results for all three polyacenes are juxtaposed to each other. While at the Franck-Condon point, each of the three noted polyacenes were found to possess a quantum yield near unity. Following the consideration of Herzberg-Teller effects, quantum yields stabilised for anthracene and tetracene to 0.19 and 0.08 respectively. Conversely, the second order corrected quantum yield for naphthalene was found to be 0.91. Analysis of this result showed that while the predicted non-radiative pathways correlate well with what should be expected, the approximation used to calculate second order corrected fluorescence, which yielded very positive results for many other molecular systems, here is unable to account for strong second order contributions, resulting in a grossly overestimated rate of fluorescence. However, substitution of an experimental radiative rate results in a quantum yield of 0.33. This work extols the importance of Herzberg-Teller terms in photophysical descriptions of chromophores, and highlights those cases in which a treatment beyond the above approximation is required.

Interexcited State Photophysics I: Benchmarking Density Functionals for Computing Nonadiabatic Couplings and Internal Conversion Rate Constants

“…Interestingly, this is not the case along any other axis. In the case of D 2 h symmetry, it is expected the vibronic structure aligns with the point group . However, only one axis is observed to display a symmetry restriction.…”

“…It is interesting to note that for every data set of perylene we see very large contributions from the Herzberg–Teller regime, unlike our previous works using the methodology. − , In fact, aside from the SVWN5/def2-TZVP and PBE/def2-TZVP, HCTH407/def2-TZVP, BHLYP/def2-TZVP, and the MN12SX/def2-TZVP data sets, the Herzberg–Teller contribution is larger than the Franck–Condon term. We could not find any information in the current body of literature to either support or oppose this contention.…”

“…However, we can approximate the rate rather effectively, assuming the Herzberg− Teller terms are not dominant. 189 VIBES can be used to generate spectra either dependent or independent of the transition dipole matrix elements. Both resulting spectra differ in spectral intensity, with this difference being related directly to the square of the transition dipole moment.…”

“…As discussed in Section , the aim of this work is to understand the influence different density functionals have on the NACMEs between electronic states. However, despite the fact this rate constant theory has already been well established in previous works, − , the full limitations of this methodology are still unknown. As such, the theory presented herein will be a summary of how to calculate the rates for fluorescence and internal conversion, how to treat the CS, and how to calculate the PLQY.…”

“…Further, we will also use this opportunity to benchmark the Plotnikov-Robinson-Jortner (PRJ) formalism. For a more complete treatment, we suggest refs , for algorithmic details, and refs , , for methodological details. All terms are in atomic units.…”