Franck–Condon simulation of photoelectron spectroscopy of HOO: Including Duschinsky effects

Geometry optimization and harmonic vibrational frequency calculations were performed on the and states of HOO and state of HOO⁻. The electron affinity and the term energy () of HOO were calculated at various theory levels. Franck–Condon analyses and spectral simulations were carried out on the and photodetachment processes. The spectral simulations of vibrational structures based on the computed Franck–Condon factors are in excellent agreement with the observed spectra. In addition, the equilibrium geometrical parameters of the state of HOO⁻ and state of HOO were obtained in the spectral simulations.     

Vibrational relaxation on the mixed vibronic levels of the and states in all-trans-neurosporene as revealed by subpicosecond time-resolved, stimulated emission and transient absorption spectroscopy

In all-trans-neurosporene, whose level is lower than the level by one vibrational quantum, the following two steps of vibrational relaxation from the mixed vibronic states were identified, in the order, stimulated emission stimulated emission transient absorption. The stimulated emission patterns were simulated by the use of Franck–Condon factors in the transitions from the pair of mixed vibronic levels down to the ground vibronic levels. The vibronic levels of the mixed and state were characterized theoretically based on the diabatic approximation.     

Solution thermodynamics near the liquid–liquid critical point. II. Excess second-order derivatives

We present a comprehensive study of the behaviour of excess second-order derivatives of binary mixtures near the liquid–liquid critical point. Specifically, excess (isobaric and isochoric) molar heat capacities ( and ), excess (isothermal and isentropic) compressibilities ( and ), and excess isobaric thermal expansivities () have been determined over the whole composition (x) range at atmospheric pressure and in the homogeneous region within (293.15–323.15) K. Results are consistent with the predictions of the current theory of critical phenomena. Remarkably, anomalous and curves in the critical region are observed. Such anomalies, which are reported here for the first time, are of significant size for and very mild in the case of , thereby indicating that volumetric effects at near-liquid–liquid criticality are, as expected, very small.     

Is Cd2 truly a van der Waals molecule? Analysis of rotational profiles recorded at the , transitions

Rotational profiles of the ²²⁸Cd₂ isotopomer recorded in the (υ′, υ″) = (26, 0), (27, 0), (42, 0), (45, 0), (46, 0), (48, 0) vibrational bands of the transition were analysed. As a result, the , , , , and excited- as well as the ground-state rotational constants of the (¹¹⁴Cd)₂ were determined. The analysis allowed determining the absolute values for the and excited- and ground-state bond lengths, respectively. The obtained result – the – distinctly shorter than that obtained with assumption of pure ground-state van der Waals bonding, supports a theoretical prediction of a covalent admixture to the bonding. Analysis of the partially-resolved rotational profile recorded in the (υ′, υ″) = (38, 0) band of the same isotopomer recorded at the transition allowed estimating the rotational constant in the B1_u state.     

DFT study of electronic structure and geometry of anionic silver clusters (n = 11, 12, 17)

Based on both total energy calculations and comparison of experimental and calculated characteristics of photoelectron spectra (PHES), the structural assignment of clusters and has been made using DFT model with recently developed S2LYP functional. The calculated characteristics of PHES for the assigned structures are in excellent agreement with the experimental ones. The electronic structure, geometry and energetic characteristics of low-lying isomers have also been studied. The calculated geometrical parameters of and clusters as well as the geometries of earlier established clusters have been compared with the geometrical characteristics of anionic sodium clusters. The structures of anionic silver and sodium clusters have been found to be very similar. The difference has been observed only for . Based on similarity of the geometries of silver and sodium clusters as well as on the comparison of calculated and experimental characteristics of PHES, the geometry of cluster has been assigned.     

Structures and properties of the tin-doped carbon clusters

A systemic density functional theory study of the tin-doped carbon clusters has been carried out using B3LYP method with TZP+ basis set. For each species, the electronic states, relative energies and geometries of various isomers are reported. Except for smaller SnC₂ and the largest , the Sn-terminated linear or quasi-linear isomer is the most stable structure for clusters. The electronic ground state is alternate between ³Σ (for n-odd member) and ¹Σ (for the n-even member) for linear SnC_n and invariably ²Π for linear and , except for SnC/SnC⁺/SnC⁻,, and . The incremental binding energy diagrams show that strong even–odd alternations in the cluster stability exist for both neutral SnC_n and anionic , with their n-even members being much more stable than the corresponding odd n − 1 and n + 1 ones, while for cationic , the alternation effect is less pronounced. These parity effects also reflect in the ionization potential and electron affinity curves. By comparing with the fragmentation energies accompanying various channels, the most favorable dissociation channel for each kind of the clusters are given. All these results are very similar to those obtained previously for the clusters.     

Excess thermodynamic properties, and for the binary systems {1,2-dichloropropane + 2-alkoxyethanols} at T = 298.15 K

This article presents the experimental data of and , obtained at T = 298.15 K and atmospheric pressure, for four binary systems composed of 1,2-dichloropropane (1,2-DCP) and four 2-alkoxyethanols. The 2-alkoxyethanols are 2-methoxyethanol (2-ME), 2-ethoxyethanol (2-EE), 2-propoxyethanol (2-PE) and 2-butoxyethanol (2-BE). The of the mixture has been shown positive for 2-ME, ‘s-shaped’ for all remaining systems, being negative at low and positive at high mole fraction of 1,2-DCP. The values for all binary mixtures are also shown both positive at low and negative at high mole fraction of 1,2-DCP. The experimental results of and were fitted to Redlich–Kister equation to correlate the composition dependence of both excess properties. In this work, data were also used to test the suitability of thermodynamic models (Wilson, NRTL, and UNIQUAC equations) based on local-composition theory. The results have been qualitatively discussed in terms of the polarity, self-association, and hydrogen bond among molecules.     

Theoretical study on the structures and properties of LiCn, , and (n = 1–10) clusters

The lithium-doped carbon clusters LiC_n, , and (n = 1–10) have been investigated systemically with density functional theory (DFT) method at the B3LYP/6-311+G* level. According to the total energies of different kinds of isomers, the LiC_n, , and (n = 1–10) clusters have Li-terminated linear ground states structures, except for LiC₂, LiC₃, , and (n = 4–6). The incremental binding energies are evaluated to elucidate the stabilities of the clusters with different numbers of carbon atoms for neutral molecules, cations, and anions, respectively. Clear even–odd alternation effects are observed for the stability of the cationic clusters and anionic clusters, while for neutral LiC_n clusters the alternation effect is less pronounced. Similarly, the ionization potentials and electron affinities of LiC_n also express an obvious parity alternation. In addition, the most favorable dissociation channels are acquired according to the fragmentation energies accompanying various pathways.     

First principles study of the structure, electronic state and stability of cations

Structural and electronic properties of semiconductor binary microclusters cations have been investigated using the B3LYP-DFT method in the ranges of n=1, 2 and m=1–7. Full structural optimization, adiabatic ionization potentials calculation and frequency analysis are performed with the basis of 6-311+G(d). The charged-induced structural changes in these cations have been discussed. The strong As–As bond is also favored over Al–As bonds in the cations in comparison with corresponding neutral cluster. With As_m forming the base, adding Al atom(s) in different positions would find the stable structures of cations quickly and correctly. , , and are predicted to be species with high stabilities and possible to be produced experimentally.     

Photoelectron spectroscopic study of iron–benzene cluster anions

Iron–benzene cluster anions, (n = 1–7, m = 1–4), were generated via laser vaporization and studied using mass spectrometry, anion photoelectron spectroscopy and in one case by density functional theory. Based on these studies, we propose that and Fe₁Bz₁ as well as and Fe₂Bz₁ exhibit half-sandwich structures, that and Fe₁Bz₂, and Fe₂Bz₂, as well as Fe₃Bz₂ and Fe₄Bz₂ are sandwich structures, and that and Fe₂Bz₃ and larger species form ‘rice-ball’ structures which in each case consist of benzene molecules surrounding an iron cluster core.     

Intense laser-induced decomposition of mass-selected 2-, 3-, and 4-methylaniline cations

Photodecomposition processes of 2-, 3-, and 4-methylaniline cations induced by a moderately intense (10¹¹ W/cm²) visible nanosecond laser field and an intense (10¹⁵ W/cm²) UV femtosecond laser field have been investigated using a tandem mass spectrometer. Highly unsaturated fragment cations such as and are dominantly produced by the nanosecond laser, while less unsaturated smaller fragment cations such as , and are produced mainly by the femtosecond laser. Ab initio calculations have also been performed to estimate the stable geometrical structures of and and those of possible intermediate ring compounds for discussing the photodecomposition pathways in intense laser fields.     

Self-assembly, crystal structure and photoluminescent properties of a novel organic–inorganic hybrid coordination polymer: [CdCl3(CH3)3NH]

A novel organic–inorganic coordination polymer [CdCl₃(CH₃)₃NH] 1 was synthesized by the reaction of CdCl₂ with trimethylamine (TMA) at 170 °C for 5 days in ethanol and structurally characterized by means of X-ray single diffraction. The title compound affords a one-dimensional chain structure. It crystallizes in hexagonal system space group P6(3)/m with , , , γ=120.00°, , Z=2, , F(000)=266, Mr=277.86, , the final R=0.0420 and ωR=0.1020 for 355 observed reflections with I>2σ(I). The title compound consists of cation [(CH₃)₃NH]⁺ and anion chain , and they are combined by static attracting forces in the crystal. TG–DTA, XRD and IR data for the title compound are reported and discussed. The photoluminescent properties of the compound 1 were also investigated.     

Ab initio electronic and rovibrational structure of

The electronic structure of the ground state of has been investigated using relativistically-corrected CCSD(T) in conjunction with ANO-RCC (Mg) and aug-cc-pVQZ (H) basis sets. The molecular potential energy surface possessed minima corresponding to both ¹A₁ and equilibrium structures (with a ¹Σ⁺ transition state). The ¹A₁ structure possessed R_e and θ_e values of 2.0297 Å and of 22.09°, respectively. The higher-energy structure exhibited an R_e value of 2.1658 Å. Property surfaces were constructed to calculate rovibrational energies and spectral line intensities for the ground states of , (¹A′) MgHD²⁺ and . For the vibration ground state of , the vibration-averaged R_e and θ_e values were calculated to be 2.0209 Å and 22.53°, respectively. The A, B and C rotational constants were calculated to be 58.0, 2.21 and 2.11 cm⁻¹, respectively.     

Theoretical mapping of new L–(N)–L family of species with donor–acceptor bonding between N and ligand L

We perform a computational mapping study of a family of new inorganic species, based on idea of donor–acceptor type bonding between N⁺ and a ligand L with a terminal electron lone pair. The nitrogen ion is seen as being in an atomic ¹D state, with empty 2p acceptor orbitals [I.S.K. Kerkines., A. Papakondylis, A. Mavridis, J. Phys. Chem. A, 2002, 106, 4435]. We consider a series of small ligands, such as PN, CCH⁻, CCCN⁻, , and others. Chemical bonding analysis confirms the suggested bonding picture as characteristic for experimentally known and as well as for most of the predicted species. A number of these new compounds is found to be thermodynamically stable with respect to the existing or . They are candidates for new synthetic targets.     

The elliptical Penning trap: Experimental investigations and simulations

The application of an additional azimuthal quadrupolar electrostatic field to a Penning trap leads to a field configuration referred to as an elliptical Penning trap. The resulting changes of the radial ion motions have been investigated experimentally and by use of simulations. The eigenfrequencies, i.e., the magnetron frequency and the reduced cyclotron frequency , are found to be shifted with respect to those of the standard Penning trap ω₋, ω₊, respectively. As the shift of the magnetron frequency is larger than that of the reduced cyclotron frequency their sum is also a function of the ellipticity and no longer equal to the cyclotron frequency in the absence of an electric trapping field ω_c=qB/m. The frequency shifts were investigated for argon and fullerene ions. The experimental studies were performed by time-of-flight (ToF) analysis of the ion cyclotron resonance and by Fourier-transform ion-cyclotron-resonance mass spectrometry (FT-ICR MS). The experimental and simulated values are in agreement with theoretical predictions [M. Kretzschmar, this issue] when the influence of higher multipole terms is taken into account.     

Modeling of vibration–electronic–chemistry coupling in the atomic–molecular oxygen system

The comprehensive analysis of the kinetic processes in the atomic–molecular oxygen system is conducted on the base of the novel state-to-state model involving both electronically and vibrationally excited O₂ molecules: and O(³P), O(¹D) atoms as well as vibrationally excited O₃(¹A₁) molecules. The model describes properly experimental data on the total removal rate of vibrationally excited molecules, the temporal evolution of the population of , and on the variation of vibrational temperature of behind strong shock wave. It is demonstrated that to describe with reasonable accuracy the variation of macroscopic flow parameters (pressure, temperature, density, and velocity) in the post shock region it is sufficient to use the widely applied model of mode approximation but in order to predict properly the species concentrations and populations of vibronic states of molecules just downstream the shock front it is needed to use state-to-state consideration.     

Thermochemical properties of the rare earth complexes with pyromellitic acid

Fourteen rare earth complexes with pyromellitic acid were synthesized and characterized by means of chemical and elemental analysis, and TG–DTG. The constant-volume combustion energies of complexes, Δ_cU, were measured by a precise rotating-bomb calorimeter (RBC-type II). Their standard molar enthalpies of combustion, , and standard molar enthalpies of formation, , were calculated at T = 298.15 K. The relationship of and with the atomic numbers of the elements in the lanthanide series was examined. The results show that a certain amount of covalence is present in the chemical bond between rare earth cations and the ligand.     

Excess molar volumes and excess molar enthalpies of binary mixtures for 1,2-dichloropropane + 2-alkoxyethanol acetates at 298.15 K

The excess molar volumes and excess molar enthalpies over the whole range of composition have been measured for the binary mixtures formed by 1,2-dichloropropane (1,2-DCP) with three 2-alkoxyethanol acetates at 298.15 K and atmospheric pressure using a digital vibrating-tube densimeter and an isothermal calorimeter with flow-mixing cell, respectively. The 2-alkoxyethanol acetates are ethylene glycol monomethyl ether acetate (EGMEA), ethylene glycol monoethyl ether acetate (EGEEA), and ethylene glycol monobutyl ether acetate (EGBEA). The of the mixture has been shown positive for EGMEA, ‘S-shaped’ for EGEEA, being negative at low and positive at high mole fraction of 1,2-DCP, and negative for EGBEA. All the values for the above mixtures showed an exothermic effect (negative values) which increase with increase in carbon number of the 2-alkoxyethanol acetates, showing minimum values varying from −374 J mol⁻¹ (EGMEA) to −428 J mol⁻¹ (EGBEA) around 0.54–0.56 mol fraction of 1,2-DCP. The experimental results of and were fitted to Redlich–Kister equation to correlate the composition dependence of both excess properties. In this work, the experimental excess enthalpy data have been also correlated using thermodynamic models (Wilson, NRTL, and UNIQUAC) and have been qualitatively discussed.     

Nucleophilic and electrophilic radical attack on maleic and fumaric acids in aqueous solution

Rate coefficients (k) of CH₂OH, , and radical addition to maleic and fumaric acids were investigated between pH 1 and 8. Strong pH dependences observed were attributed to changes in protonation states of acids: H₂X, HX⁻ and X²⁻. k of CH₂OH, , addition to fumaric acid decreased in the order k_H2F>k_HF^->k_F^2- in agreement with the nucleophilic character of reaction. The electrophilic radical showed opposite tendency. With maleic acid the monoanion had the highest reactivity towards nucleophilic and the lowest one towards electrophilic radicals. This is attributed to a prevalence of steric over polar effects for HM⁻.