Finite-temperature Wigner phase-space sampling and temperature effects on the excited-state dynamics of 2-nitronaphthalene

Abstract

The concept of finite temperature Wigner phase-space sampling allowing the population of vibrationally excited states is introduced and employed to study temperature effects on the absorption spectrum of 2-nitronaphtalene (2NN) and its relaxation dynamics. It is found that, despite the fact that the general deactivation mechanism of 2NN after light irradiation does not change with increasing temperature, i.e., after excitation to the singlet manifold, 2NN deactivates via internal conversion in less than 100 fs and then undergoes intersystem crossing to the triplet manifold before decaying to the lowest triplet state in less than 150 fs, the intersystem crossing rate increases at higher temperatures. This increase is attributed to the appearance of a new deactivation pathway, which is not operative at lower temperatures. The present example illustrates that appropriate initial conditions beyond the idealized temperature of 0 K are indispensable to obtain reliable excited state mechanisms, which can be then related to experimental conditions.

The importance of finite temperature and vibrational sampling in the absorption spectrum of a nitro-functionalized Ru(ii) water oxidation catalyst

“…[14][15][16][17] Nuclear vibration effects can even change the character of the absorption bands, as it has been shown for some nitroaromatic compounds. [18][19][20] Despite essential, only a few studies [21][22][23][24] take into account the influence of vibrational sampling on the simulation of absorption spectra of systems in general and of transition metal complexes in particular.…”

“…In this work, we investigate the absorption spectra of Ru(dppip-NO 2 ) addressing the influence of the chemical modification of the ligand and of ligand (de)protonation, paying particular attention to vibrational sampling. In particular, we would like to find out how vibrational sampling effects are relevant in the absorption spectra of the different protonated forms of Ru(dppip-NO 2 ) and whether previously reported quenching of the charge transfer character by vibrational effects in organic nitro-aromatic compounds, [18][19][20] here translated into the torsional motion within the functionalized ligand, affects the absorption.…”

Assessing Configurational Sampling in the Quantum Mechanics/Molecular Mechanics Calculation of Temoporfin Absorption Spectrum and Triplet Density of States

“…In the first case, a ground-state molecular-dynamics (MD) simulation is performed, in which the system is in thermal equilibrium at a certain temperature. In the quantum sampling, the configurational space is represented by the quantum-mechanical distribution of the population of the vibrational ground state if one assumes a temperature of 0 K; if temperature effects are included, the distribution also considers the population of vibrationally excited states of the electronic ground state [ 41 ]. Both approaches can also be combined by performing quantum sampling for the chromophore and thermal sampling for the solvent.…”

Orbital-free photophysical descriptors to predict directional excitations in metal-based photosensitizers

“…Then, a quantum ensemble of 100 geometries at 300 K was considered for each of the spin cases ( 1 MLCT and 3 MLCT) to account for an appropriate conformational sampling due to nuclear vibrational energy. 38,40,47,48 The computation of the 1 MLCT absorption band involved the lowest 25 singlet states for each geometry (i.e. 25 Â 100 geometries ¼ 2500 excited states per derivative) and the computation of the 3 MLCT emission band involved 1 state for each geometry (i.e.…”