Synthesis of novel tetraoxygenated homoisoflavanones

860-86

Electron interactions with AlF

The electron-impact elastic and electronic excitation cross sections of aluminum monofluoride are reported using the R-matrix method up to energies less than the ionization threshold. The scattering studies are performed using different basis sets and models like the static exchange, static exchange with polarization, and close-coupling. The bound state nature of resonance and convergence of cross sections is discussed along with other resonances. The differential and momentum transfer cross sections are also presented. The ionization cross sections are computed using all-electron and effective core potentials from the binary-encounter-Bethe model of electrons. The dissociative electron attachment cross sections are also estimated. Shape and core resonances have been identified

Elastic and vibrationally-resolved excitation cross sections for electron impact with MgF radical using R-matrix

We report the calculations of elastic and vibrationally- resolved electronic excitation cross sections by an electron impact on MgF radical by using the R-matrix approach in the 0.1–10 eV energy range. A systematic study considering various basis sets, polarisation and the Born closure technique is performed. For bench mark study, we have used the basis sets like 6-31G*, 6-311G*, DZP and cc-pVTZ to understand the bound state properties of MgF. The final target and hence the scattering calculations are reported using the cc-pVTZ basis set as it yielded the best ground state energy, dipole moment and the energy thresholds of the excited states. Various scattering models like Static Exchange (SE), Static-Exchange-Polarisation (SEP) and Close-Coupling (CC) models are invoked to investigate the role of correlation and polarisation effects on the cross sections. The trial wave function of the entire scattering system (MgF + electron) consists of the ground and many excited states. These target states are constructed by including correlation effects via configuration interaction (CI) approach. Other types of cross sections like differential, momentum transfer, ionisation and elastic rate constants are also reported

Study of electron collision from bioalcohols from 10 to 5000 eV

The electron-impact cross sections are obtained for alkyl bioalcohols in the energy range from ionization threshold to 5000 eV. The molecular wavefunction of targets are obtained from the multi-centre expansion of the Gaussian-type orbitals within a single determinant Hartree–Fock self consistent field scheme. The three dimensional molecular quantities like wavefunction, density and potentials are expanded at the centre of mass of molecule using the Single Centre Expansion formalism. The interaction potential is assumed to be local in nature and is approximated by static, correlation-polarization and exchange effects. The elastic cross sections are obtained after solving the coupled integro-radial differential equations using Volterra integral form. The inelastic ionization cross sections are computed by Binary-Encounter-Bethe method. The total cross sections are obtained after summing the elastic and inelastic cross sections incoherently. The scattering calculations were also performed for glycerol and phenol. The cross sections obtained from present methodology are in good agreement with available results. The study of e− scattering from different targets has helped in expressing a relationship between the total cross section of two different targets in a most simple but effective way

A study of electron scattering from 1-1 C

Various electron- impact cross sections of 1-1-C2H2F2 molecule are reported in the energy range from 0.1 to 5000 eV using the cc-pVTZ basis set. The molecular wavefunctions of the target are obtained from the multi-center expansion of the Gaussian-type orbitals within a single determinant Hartree Fock self consistent field scheme. The elastic cross sections in the low energy range (below ionization threshold) are reported in different scattering models like static-exchange, static-exchange-polarization and close-coupling using the R-matrix approach. The resonances detected in these scattering models are comprehensively analysed. The computed shape resonances are in an excellent agreement with the experimental and theoretical values. In addition to elastic rate coefficients, we have also reported differential, momentum transfer and electronic excitation cross sections. The present elastic cross sections are in good accord with the other ab-initio calculations. However, the total cross sections obtained lie systematically above the experimental results. The Single Center Expansion (SCE) involving the use of local potentials is invoked to obtain differential, elastic and momentum transfer cross sections at energies beyond ionization threshold. The ionization cross sections are obtained using the Binary-Encounter-Bethe model. The total cross sections are obtained by incoherently summing the elastic and inelastic cross sections. The SCE based results and total cross sections are in good agreement with the experimental and theoretical results. The cross sections like elastic, momentum transfer and total obtained from two different approaches are found to match smoothly near ionization threshold thus helping in estimating the cross sections over a wide energy range

Low to high energy electron interactions with AlCl

Various cross sections due to electron-impact are reported for aluminum monochloride (Al$$^{35}$$Cl) from low to high energy range. The scattering calculations in the low energy range (less than ionization) are accomplished using the well-known R-matrix method. Different scattering models are used to assess the convergence of results and to analyse the formation of resonances. All models converge around 4 eV, showing that the impact of correlation-polarization ceases on scattering. The shape resonance is observed in static-exchange model in the $$C_{2v}$$ point group corresponding to $$^2B_{1,2}$$ scattering symmetry. It becomes a bound state in static-exchange-polarization model. In 18-states close-coupling model, this resonance state is almost bound. The elastic differential, integral and momentum transfer cross sections beyond ionization threshold are reported by using local potential-based single-center-expansion approach. A near overlapping nature of elastic cross sections is noticed from two different theories at the ionization threshold. This helps to predict the estimates of elastic cross sections over a broad energy range. The ionization cross sections are computed adopting the semi-empirical binary-encounter-Bethe model for electrons. The dissociative electron attachment process is also discussed

Elastic and Inelastic Cross Sections for Low-Energy Electron Collisions with ClF Molecule Using the R-Matrix Method

The ClF molecule belongs to an interhalogen family and is important in laser physics and condensed phase molecular dynamics. The elastic and excitation scattering cross sections are obtained in a fixed nuclei approximation using the UKRmol+ codes based on R-matrix formalism. The scattering calculations were performed in the static-exchange (SE), static-exchange-plus-polarisation (SEP), and close-coupling (CC) models. Three CC models with different target states were employed, namely, the 1-state, 5-states, and 12-states. In the CC model, the target states were represented by configuration interaction (CI) wavefunctions. A good agreement of dipole and quadrupole moments of the ground state was obtained with the experimental values, which indicates a good representation of the target modelling. The study predicted the existence of a shape resonance in the SE, SEP, and 5-states CC models. This resonance vanished in the 12-states CC model. The excitation cross sections from ground to the lowest two excited states were also reported. The elastic differential and momentum transfer cross sections were obtained in the 12-states CC models. The contribution of long-range interactions to elastic scattering was included via Born closure approach. The quantities like collision frequencies and rate coefficients were also presented over a wide range of electron temperatures. The ionization cross sections were computed using the binary-encounter-Bethe (BEB) model. The results were reported in C2v point group representation

Electron-impact cross sections of X

Various electron-impact cross sections are obtained for halogenated derivatives of formaldehyde like H2CO, F2CO, Cl2CO, Br2CO using the Single Centre Expansion method. The molecular wavefunction of the targets are obtained from the multi-centre expansion of the Gaussian-type orbitals within the single determinant Hartree Fock self consistent field scheme. The effects due to static, correlation-polarization and exchange included to model the electron-molecule interactions are approximated by their local nature. The correlation-polarization potential includes short and long range polarization electron dynamical effects. The dipole and higher order multipole terms are considered in the multipole expansion of the target at centre of mass. The coupled scattering equations are solved using Volterra integral form to obtain the elastic cross sections. The inelastic contributions to collision process are approximated by ionization cross sections. The two cross sections are added to obtain the total cross sections from ionization threshold to 5 keV. The collision data generated from this approach are consistent with the available results. The study of scattering from homologous series has helped in proposing a simple empirical formula to estimate the total cross sections for any member of the homologous family

Electron impact partial ionization cross sections of methyl alcohol up to 5 keV using the mass spectrometry data

The electron impact partial ionization cross sections (PICSs) of methyl alcohol fragments are reported from ionization threshold to 5 keV. The calculations employ use of electron impact mass spectrometry data and a modified form of binary-encounter-Bethe (BEB) model. In the modified-BEB approach, the binding energy of each occupied molecular orbital is incremented by an amount such that the highest occupied molecular orbital reflects the appearance potential of a particular fragment. The PICSs are then obtained by appropriately scaling the cross section data using the branching ratios (BR). The BRs can either be obtained from the cross section data or using the mass spectrometry data at an energy at which the mass spectrum is recorded. The PICSs are summed to obtain the total ionization cross sections (TICS) of the methyl alcohol. The results are in good agreement with the experimental results and are superior to the existing theoretical results. A simple approach like this in conjunction with mass spectrometry would be of immense help in modeling and interpretation of ionization data. The study reveals the need for more consistent ion energetics and mass spectrometry data for an accurate modeling of PICSs

Partial Ionization Cross Sections of Tungsten Hexafluoride Due to Electron Impact

The ionization data of a neutral molecule are crucial to model the energy deposition and dissociative ionization process. We study theoretically the electron impact ionization process and report on the dissociative ionization cross sections of the tungsten hexafluoride cations invoking the modified-binary-encounter-Bethe model. In this model, the binary-encounter-Bethe model is modified by applying the transformation to the binding energies of the molecular orbitals and then normalizing the partial ionization cross sections of the cations using the branching ratios. The normalization is performed at a particular energy and ensures that the branching ratios of different fragments are summed to unity. The model yielded satisfactory results for both the singly and doubly ionized ions. The approach validates the results of Basner et al. The advantages and limitations of this model are also discussed. This work corroborates the importance of mass spectrometry data in the proper understanding of the ionization process