Genetic algorithm for obtaining potential energy curve of diatomic molecules based on dispersed fluorescence spectra.

The method for reconstruction of an adiabatic potential energy curve from experimental dispersed fluorescence spectra has been developed. The novelty of the method relies on a unique approach of simultaneous use of [Formula: see text] and [Formula: see text] parts of the spectrum. The method is based on the Genetic Algorithm (GA) procedure and determines potential energy curve integrally, below and above the dissociation energy limit. The method was tested on the artificially generated reference spectrum as well as experimental spectrum of [Formula: see text] transition in Hg[Formula: see text]. The tests show very good accuracy of simulation based on GA results with artificially generated reference spectrum as well as with the experimental one.

Electron Trap Depths in Cubic Lutetium Oxide Doped with Pr and Ti, Zr or Hf─From Ab Initio Multiconfigurational Calculations.

We propose a universal approach to model intervalence charge transfer (IVCT) and metal-to-metal charge transfer (MMCT) transitions between ions in solids. The approach relies on already well-known and reliable ab initio RASSCF/CASPT2/RASSI-SO calculations for a series of emission center coordination geometries (restricted active space self-consistent field, complete active space second-order perturbation theory, and restricted active space state interaction with spin-orbit coupling). Embedding with ab initio model potentials (AIMPs) is used to represent the crystal lattice. We propose a way to construct the geometries via interpolation of the coordinates obtained using solid-state density functional theory (DFT) calculations for the structures where the activator metal is at specific oxidation (charge) states of interest. The approach thus takes the best of two worlds: the precision of the embedded cluster calculations (including localized excited states) and the geometries from DFT, where the effects of ionic radii mismatch (and eventual nearby defects) can be modeled explicitly. The method is applied to the Pr activator and Ti, Zr, Hf codopants in cubic Lu2O3, in which the said ions are used to obtain energy storage and thermoluminescence properties. Electron trap charging and discharging mechanisms (not involving a conduction band) are discussed in the context of the IVCT and MMCT role in them. Trap depths and trap quenching pathways are analyzed.

Observation of gerade Rydberg state of Cd2 van der Waals complex cooled in free-jet expansion beam and excited using optical-optical double resonance method.

We report on the observation of a gerade Rydberg electronic energy state of Cd2 van der Waals (vdW) complex vibrationally cooled in a free-jet expansion beam. Cd2 in the beam were excited from the X10g+(51S0) ground via the b30u+(53P1) intermediate to the final gerade state using optical-optical double resonance (OODR) method. A pronounced vibrational progression with partly resolved isotopologue components was recorded and analyzed. The analysis of isotopic separation indicated the excitation to high vibrational levels (υ'≈50). A comparison with the result of ab initio calculations reveals, that Cd2 was most probably excited to the 31g -state correlating with the 63S1 atomic asymptote.

Ab initio theoretical study on the 4f(2) and 4f5d electronic manifolds of cubic defects in CaF2:Pr3+.

Wave function-based embedded cluster ab initio calculations have been carried out in order to study the 4f(2) and 4f5d energy levels of the cubic substitutional defect of Pr-doped CaF2. The 4f(2) → 4f5d absorption spectrum and 4f5d → 4f(2) emission spectrum have been calculated. The 4f(2 1)S0 level is found to be immersed in the 4f5d(eg) manifold, so that no quantum cutting from (1)S0 can occur and only strong 4f5d(eg) → 4f(2) emission is predicted, which supports previous assumptions made in order to explain results in CaF2:Pr(3+). The details of the 4f(2) → 4f5d(eg) and 4f(2) → 4f5d(t2g) bands of the absorption spectrum are interpreted and assignments are made. The lowest level of the 4f5d(eg) configuration is found to have 80% of singlet character, in opposition to Hund's Rules, and the issue is discussed in detail. The comparison between the experimental 4f5d(eg) → 4f(2) high resolution emission spectrum of the cubic site of CaF2:Pr(3+) and the calculated emission spectra from the two lowest 4f5d(eg) states 1T2u((1)T2u) and 1Eu(1(3)T2u) suggests the possibility that the experimental emission of the cubic Pr defect of CaF2:Pr(3+) is in fact a multiple emission.