Theoretical re-investigation on the N–N bond breaking of N2O+ cations in the A2Σ+ and B2Π states at the CASPT2 level

The N+ Formation Mechanism of Vibrationally Selected N2O+ Ions in the C2Σ+ State: A TPEPICO Imaging Study

“…To clearly understand the dissociation characteristics of the C 2 Σ + state, we performed high-level quantum chemical calculations on its optimized geometry and mapped 2D potential energy surface along the N–NO coordinate and bond angle at the CASPT2//cc-pVQZ level, similar to our recent calculations of the A 2 Σ + and B 2 Π states . In the Franck–Condon region, a linear optimized geometry is affirmed for the C 2 Σ + state with R (N–N) of 1.119 Å and R (N–O) of 1.209 Å.…”

“…Figure shows the calculated 2D potential energy surface of the C 2 Σ + state along the N–NO coordinate and bond angle. Notably, the pattern is generally similar to those of the lower excited states, A 2 Σ + and B 2 A′ (the A′ component of B 2 Π in bent geometry) . In brief, from the global minimum of the C 2 Σ + state (linear geometry) in the Franck–Condon region, a relatively high barrier of ∼1.8 eV exists to break the N–NO bond of N 2 O + (C 2 Σ + ) along the linear configuration.…”

“…Notably, the pattern is generally similar to those of the lower excited states, A 2 Σ + and B 2 A′ (the A′ component of B 2 Π in bent geometry). 17 ) Ions at the (0,0,0), (1,0,0), and (0,0,1) VibronicLevels vibronic levels anisotropy parameter,…”

“…9,16 Very recently, we have conducted high-level ab initio calculations on N 2 O + in the A 2 Σ + and B 2 Π states, using the complete active space self-consistent field (CASSCF) and multireference second-order perturbation theory (CASPT2). 17 By mapping two-dimensional (2D) multistate potential energy surfaces along the N−NO bond length and N−N−O angle, we have proposed comprehensive N−NO bond-fission mechanisms in linear and bent geometries to explain ro-vibrational distributions of the NO + fragment observed in experiments, in which the avoided crossing and the coupling of spin states play crucial roles. 17 The decomposition of N 2 O + (C 2 Σ + ) ions is more complex, and many dissociation channels are open owing to the increase of excitation energy and multistate coupling.…”

“…17 By mapping two-dimensional (2D) multistate potential energy surfaces along the N−NO bond length and N−N−O angle, we have proposed comprehensive N−NO bond-fission mechanisms in linear and bent geometries to explain ro-vibrational distributions of the NO + fragment observed in experiments, in which the avoided crossing and the coupling of spin states play crucial roles. 17 The decomposition of N 2 O + (C 2 Σ + ) ions is more complex, and many dissociation channels are open owing to the increase of excitation energy and multistate coupling. 18,19 Four fragment ions, NO + , N 2 + , O + , or N + , were all observed in experiments, and their branching ratios exhibited some degree of vibrational dependence.…”