Photodissociation of ozone in the Hartley band: Product state and angular distributions

Product state properties from the photodissociation of ozone in the ultraviolet Hartley band are investigated by trajectory surface-hopping calculations. The diabatic B and R state potential energy and coupling surfaces of Schinke and McBane [J. Chem. Phys. 132, 044305 (2010)] are employed. The properties computed include rotational and vibrational distributions in both the singlet and triplet channels, the total internal energy distribution in the triplet channel, and the photodissociation anisotropy parameter β role= presentation style= display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3eββ in the singlet channel. A method for computing β role= presentation style= display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3eββ from trajectories computed in internal Jacobi coordinates is described. In the singlet channel, the vibrational distribution is in good agreement with the experimental results. The observed increase in β role= presentation style= display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3eββ with increasing photolysis wavelength is reproduced by the calculations and is attributed to the effects of the bending potential on the B state late in the fragmentation. The computed β role= presentation style= display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3eββ values are too high with respect to experiment, and the peaks jmax role= presentation style= display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3ejmaxjmax of the singlet-channel rotational distributions are too low; these discrepancies are attributed to a too steep bending potential at long O–O distances. In the triplet channel, the main part of the internal energy distribution is described well by the calculations, although the detailed structures observed in the experiment are not reproduced. The experimental rotational distributions are well reproduced, although the maxima appear at slightly too high j role= presentation style= display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3ejj. The triplet state product energy distributions are shown to depend largely on the distribution of hopping points onto the R state surface. A Landau–Zener model constructed as a function of the O2 role= presentation style= display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3eO2O2 bond distance provides a good physical description of the two-state dynamics. The high internal energy O2 role= presentation style= display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3eO2O2 products that cannot be attributed to the excitation of the Herzberg states remain unexplained

The Ultraviolet Spectrum of OCS from First Principles: Electronic Transitions, Vibrational Structure and Temperature Dependence

Global three dimensional potential energy surfaces and transition dipole moment functions are calculated for the lowest singlet and triplet states of carbonyl sulfide at the multireference configuration interaction level of theory. The first ultraviolet absorption band is then studied by means of quantum mechanical wave packet propagation. excitation of the repulsive 21A\u27 state gives the main contribution to the cross section. Excitation of the repulsive 11A state is about a factor of 20 weaker at the absorption peak (Eph ≈ 45 000 cm-1) but becomes comparable to the 21A\u27 state absorption with decreasing energy (35 000 cm-1) and eventually exceeds it. Direct excitation of the repulsive triplet states is negligible except at photon energies Eph \u3c 38 000 cm-1. The main structure observed in the cross section is caused by excitation of the bound 23A state, which is nearly degerate with the 2 1A\u27 state in the Franck-Condon region. The structure observed in the low energy tail of the spectrum is caused by excitation of quasi-bound bending vibrational states of the 21A\u27 and 11A electronic states. The absorption cross sections agree well with experimental data and the temperature dependence of the cross section is well reproduced

Multi-State Analysis of the OCS Ultraviolet Absorption Including Vibrational Structure

The first absorption band of OCS (carbonyl sulfide) is analyzed using potential energy surfaces and transition dipole moment functions of the lowest four singlet and the lowest four triplet states. Excitation of the 21A\u27 state is predominant except at very low photon energies. It is shown that the vibrational structures in the center of the band are due to excitation of the 23A triplet state, whereas the structures at the very low energies are caused by bending excitation in the potential wells of states 21A\u27 and 11A

Photodissociation of N\u3csub\u3e2\u3c/sub\u3eO: Energy Partitioning

The energy partitioning in the UV photodissociation of N2O is investigated by means of quantum mechanical wave packet and classical trajectory calculations using recently calculated potential energy surfaces. Vibrational excitation of N2 is weak at the onset of the absorption spectrum, but becomes stronger with increasing photon energy. Since the NNO equilibrium angles in the ground and the excited state differe by about 70°, the molecule experiences an extraordinarily large torque during fragmentation producing N2in very high rotational states. The vibrational and rotational distributions obtained from the quantum mechanical and the classical calculations agree remarkably well. The shape of the rotational distributions is semi-quantitatively explained by a two-dimensional verision of the reflection principle. The calculated rotational distribution for excitation with λ = 204 nm and the translational energy distribution for 193 nm agree well with experimental results, except for the tails of the experimental distributions corresponding to excitation of the highest rotational states. Inclusion of nonadiabatic transitions from the excited to the ground electronic state at relatively large N2-O separations, studied by trajectory surface hopping, improves the agreement at high j

Production of O\u3csub\u3e2\u3c/sub\u3e Herzberg States in the Deep UV Photodissociation of Ozone

High-resolution imaging experiments combined with new electronic structure and dynamics calculations strongly indicate that the O(3P)+O2 products with very low kinetic energy release (Etr2: A\u27 3Δu(v=0, 1, 2) and A 3Σ+u(v=0, 1). This interpretation contradicts the earlier assignment to very high (v≥26) vibrational states of O2(3Σ-g)

Exploring Renner-Teller Induced Quenching in the Reaction H(\u3csup\u3e2\u3c/sup\u3e\u3ci\u3eS\u3c/i\u3e)+NH(\u3ci\u3ea\u3c/i\u3e\u3csup\u3e1\u3c/sup\u3eΔ): A Combined Experimental and Theoretical Study

Experimental rate coefficients for the removal of NH(a1Δ) and ND(a1Δ) in collisions with H and D atoms are presented; all four isotope combinations are considered: NH+H, NH+D, ND+H, and ND+D. The experiments were performed in a quasistatic laser-flash photolysis/laser-induced fluorescence system at low pressures. NH(a1Δ) and ND(a1Δ) were generated by photolysis of HN3 and DN3, respectively. The total removal rate coefficients at room temperature are in the range of (3-5) x 1013 cm3 mol-1 s-1. For two isotope combinations, NH+H and NH+D, quenching rate coefficients for the production of NH(X 3Σ-) or ND(X 3Σ-) were also determined; they are in the range of 1x1013 cm3 mol-1 s-1. The quenching rate coefficients directly reflect the strength of the Renner-Teller coupling between the 2A and 2A\u27 electronic states near linearity and so can be used to test theoretical models for describing this nonadiabatic process. The title reaction was modeled with a simple surface-hopping approach including a single parameter, which was adjusted to reproduce the quenching rate for NH+H; the same parameter value was used for all isotope combinations. The agreement with the measured total removal rate is good for all but one isotope combination. However, the quenching rates for the NH+D combination are only in fair (factor of 2) agreement with the corresponding data

Assessing the effects of flood resilience technologies

The impacts of floods on housing in urban areas are increasing due to both the intensification of extreme weather events and the development of settlements together with the rising vulnerability of assets in areas at risk. Therefore, the improvement of buildings’ resilience properties to better cope with flooding is becoming a key issue in European research in recent years. The implementation of flood resilience technologies (FRe T) on a building scale provides a previously untapped potential to reduce flood damage because of insufficient transparency of their effects. To overcome this obstacle the paper covers an extended methodological framework for the analysis of the potential of FRe T. This framework is based a synthetic approach on flood damage simulation that supports the assessment of singular FRe T or the combination of serval FRe T options and permits the derivation of optimised FRe T alternatives. The approach his been tested, amongst other selected European study sites, in Heywood/Greater Manchester(United Kingdom) to analyse its functionality considering various flood types as well as different national and local contexts