Accurate double many-body expansion potential energy surface for the 21A′ state of N2O

Accurate many-body expansion potential energy surface for SiH2 (11 A′) using a switching function formalism

An accurate many-body expansion potential energy surface for the ground state of SiH2 is reported. To warrant the correct behavior at the Si (1D) + H2 (X1Σ+g) dissociation channels...

Photodissociation Dynamics of Nitrous Oxide near 145 nm: The O(1S0) and O(3P J=2,1,0) Product Channels

We report the study of photodissociation dynamics of nitrous oxide in the vacuum ultraviolet region, using the time-sliced velocity map ion imaging technique. Ion images of the O(¹S₀) and O(³P _J=2,1,0) products were measured at nine photolysis wavelengths from 142.55 to 148.79 nm. The product channels O(¹S₀) + N₂(X¹Σ_g⁺) and O(³P _J=2,1,0) + N₂(A³Σ_u⁺) have been observed. For these dissociation channels, the total kinetic energy releases of the dissociated products were acquired. With vibrational structures of the N₂ coproducts partially resolved in the experimental images, the branching ratios of different vibrational states of the N₂ coproducts were determined, and the vibrational state specific anisotropy parameters (β values) were derived. Analysis shows that the O(¹S₀) + N₂(X¹Σ_g⁺) channel is primarily formed via nonadiabatic couplings between the C (¹Π) state and the higher-lying D (¹Σ⁺) state of the N₂O. A moderate rotational excitation and high vibrational excitation of N₂(X¹Σ_g⁺) products have been observed through this pathway. On the other hand, for the O(³P _J=2,1,0) + N₂(A³Σ_u⁺) channels, where a slightly higher rotational excitation of N₂ coproducts have been observed, the possible pathway would be via nonadiabatic couplings from the C (¹Π) state to the lower-lying A(¹Σ^-)state.

VUV Photodissociation Dynamics of Nitrous Oxide: The N((2)DJ=3/2,5/2) and N((2)PJ=1/2,3/2) Product Channels

We report on an experimental study of the vacuum ultraviolet photodissociation dynamics of nitrous oxide as a function of photolysis wavelength. In this study, both the N((2)DJ) + NO(X(2)Π) and N((2)PJ) + NO(X(2)Π) product channels were investigated using the time-sliced velocity ion imaging technique. Images of the N((2)DJ=5/2,3/2) and N((2)PJ=3/2,1/2) products were measured at seven and ten, respectively, photolysis wavelengths between 124.44 and 133.20 nm. The vibrational states of the NO products were partially resolved in the acquired raw ion images. The total kinetic energy release and the branching ratios of different vibrational states of NO products were determined. The vibrational state distributions of NO were found to be inverted for the N((2)DJ=5/2,3/2) and N((2)PJ=3/2,1/2) product channels. This phenomenon indicates that the N-O bond is highly vibrational excited during the breaking of the N-N bond. Vibrational state resolved anisotropic parameters β in both the N((2)DJ) and the N((2)PJ) channels were acquired. The small β values (around 0.5) in the dissociation process suggest that transition states in a bent configuration play an important role in the formation of N + NO products.

Global triplet potential energy surfaces for the N2(X(1)Σ) + O((3)P) → NO(X(2)Π) + N((4)S) reaction

This work presents two global triplet potential energy surfaces (PESs) for the high-energy reaction N2(X(1)Σ) + O((3)P) → NO(X(2)Π) + N((4)S)-in particular, for the lowest energy (3)A' and (3)A″ PESs. In order to obtain the energies needed for fitting analytic surfaces, we carried out multireference configuration interaction (MRCI) calculations based on wave functions obtained from state-averaged complete active space self-consistent field calculations for 2280 geometries for the three lowest (3)A″ states and for 2298 geometries for the three lowest (3)A' states. The lowest-energy (3)A' and (3)A″ states at each of these geometries were then improved by applying the dynamically scaled external correlation (DSEC) method to all MRCI points, and the resulting DSEC energies were used for construction of the ground-state PES for each symmetry. The many-body component of the DSEC energies for the three-dimensional (3)A' and (3)A″ PESs was then least-squares fitted in terms of permutationally invariant polynomials in mixed exponential-Gaussian bond order variables. The global and local minima as well as the transition structures of both the (3)A' and the (3)A″ analytic PES were explored. In agreement with previous work, we find that the reverse reaction is barrierless on the (3)A″ surface along the minimum energy pathway. However, we have explored several new local minima and transition structures on the (3)A' PES. Furthermore, based on the newly found minima and transition structures, two independent reaction mechanisms have been illustrated for the reaction path on the (3)A' PES. The analytic surfaces may be used for dynamics calculations of electronically adiabatic reactive scattering and energy transfer.