A computational study of photoisomerization in Al3O3− clusters

Abstract

Ab initio calculations are employed to understand the photoisomerization process in small Al 3 O 3 Ϫ clusters. This process is the first example of a photoinduced isomerization observed in an anion cluster gas-phase system. Potential energy surfaces for the ground state and the excited state ͑S 1 and T 1 ͒ are explored by means of B3LYP, MP2, CI-singles, and CASSCF methods. We demonstrate that the isomerization process occurs between the global minimum singlet state Book structure (C 2v , 1 A 1 ) and the triplet state Ring structure (C 2v , 3 B 2 ). The calculated vertical excitation energy is 3.62 eV at the CASSCF level of approximation, in good agreement with the experimental value ͑3.49 eV͒. A nonplanar conical intersection, which hosts the intersystem crossing between the S 1 and T 1 surfaces is identified at the region of around R(1,6)ϭ2.4 Å. Beyond the experimental results, we predict, that this isomerization is reversible upon absorption of a phonon with energy of 1.92 eV. Our results describe a unique system, whose structure depends on its spin multiplicity; it exists as the Book structure on singlet states and as the Ring structure on triplet states.

Separating contributions from multiple structural isomers in anion photoelectron spectra: Al3O3− beam hole burning

“…This was based on their new DFT and ab initio calculations on the excited singlet and triplet states of the various anion structural isomers. 17 The electron affinity of this ring structure calculated by Cui et al at the B3LYP level is 2.11 eV ͑Ghanty and Davidson calculate the EA to be 2.09 eV 2 ͒. If this were being generated, photoelectron signal from this anion should overlap with band XЈ.…”

Photoelectron spectroscopy and density functional theory study of TiAlOy− (y=1–3) and TiAl2Oy− (y=2–3) clusters

“…11,42,46,47 This configuration is based on isomer 3A of TiAlO 3 − by adding an extra Al to the terminal oxygen atom.…”

“…Theoretically, a number of methods were employed to explore the structures and bonding of the clusters of titanium [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] and aluminum oxides. [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] Although the clusters of titanium oxide and aluminum oxide were intensively investigated, the study of hybrid titanium-aluminum oxides is quite rare. In the past few years, it has been proposed that hybrid titanium-aluminum oxides might have potential applications as a high-dielectric ͑high-K͒ material for the next generation of complementary metal-oxide-semiconductor ͑CMOS͒ gates.…”

Density functional study of neutral and anionic AlOn and ScOn with high oxygen content

“…Two isomers of Al 3 O 3 − were identified in its photoelectron spectrum 15. The energies of an extra electron detachment from the Al n O m − anions were computed using various density functional theory (DFT) and post‐Hartree‐Fock (HF) methods including electron propagator techniques 16–21. Among theoretically studied clusters are the (AlO 2 ) 2 dimer,22 the (AlO) 2 dimer,23 the Al(O 2 ) n series n = 1–3,24 the (AlO) 4 tetramer,25 Al n O m ( n , m = 1–4),26 (Al 2 O 3 ) 4 , and (Al 2 O 3 ) 4 + 27.…”