Modelling the vibrationally mediated photo-dissociation of acetylene

Abstract

A ten singlet state vibronic coupling Hamiltonian was constructed describing the seven internal coordinates of acetylene. A Σ symmetry-adapted polynomial expansion of the nuclear coordinates over diabatic elements was used to fit adiabatic energies obtained from ab initio calculations. The fitted vibronic Hamiltonian was subsequently used to model vibrationally mediated photo-dissociation (VMD) experiments. The model suggests that some control over dissociation channels might be achieved by choosing different ranges of pre-excitation and UV-excitation energies.

Light-induced photodissociation in the lowest three electronic states of the NaH molecule

“…Although many of these works treat the dynamical problem of diatomics starting investigations from the simplest hydrogen-like ions or molecules to systems with large numbers of electrons, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] other relevant papers are tackling the problem of photodissociation and fragmentation of polyatomics, as well. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] Molecular dissociation is usually treated within the Born-Oppenheimer (BO) framework, which relies on the separation of the motions of the electrons and nuclei due to different time scales of their motion. In most cases, this approach works well and provides an acceptable treatment of dynamical processes.…”

“…Although many of these works treat the dynamical problem of diatomics starting investigations from the simplest hydrogen-like ions or molecules to systems with large numbers of electrons, 1–16 other relevant papers are tackling the problem of photodissociation and fragmentation of polyatomics, as well. 17–36…”

Excited-state dynamics of [Mn(im)(CO)3(phen)]+: PhotoCORM, catalyst, luminescent probe?

“…Recent simulations are mostly devoted to isomerization, fragmentation or charge transfer in organic chromophores. [28][29][30] Simulations of quantum dynamics including dissociative coordinates 31 are still scarce and only one example has been reported for a 1 st -row transition metal complex, namely the ultrafast photolysis of the heme-CO complex. 32 The present study is devoted to quantum dynamics simulations capable to follow the competition between fluorescence and carbonyl loss in [Mn(im)(CO)3(phen)] + , in particular the axial carbonyl, see Scheme 1.…”

Modelling the non-radiative singlet excited state isomerization of diphenyl-acetylene: A vibronic coupling model

“…The expansion coefficients of the diabatic model are chosen so that the eigenvalues of the potential operator map on to the adiabatic potential surfaces. Such models have been shown to accurately reproduce the short-time dynamics of non-adiabatic systems [20,21,22,23,24]. For describing tolane, normal mode coordinates were used and the diabatic potential energy surfaces expanded around the Frank- A u (5.23) A g (4.36) A g (∼5.30) A (6.33) Condon point.…”