Note: Calculation of the branching ratios for the predissociation of the Rydberg CO W1Π(v=1) level

Strong and selective isotope effect in the vacuum ultraviolet photodissociation branching ratios of carbon monoxide

“…This model was recently discussed by Thiemens and coworkers for explaining the variations of absorption line positions and oscillator strengths of N 2 due to isotopic substitution, which should also work for the photoabsorption and photodissociation processes of CO as pointed out by those authors 34,41 . This is actually similar to the coupled equations method used by Lefebvre-Brion and coworkers for quantitatively predicting the line positions, oscillator strengths, accidental perturbations, and photodissociation branching ratios of CO and their dependences on the isotopic substitution 40,42,43 . In this model, two bound diabatic potential curves with different bonding types, usually one Rydberg and one valence, cross at certain point and interact with each other through an electronic coupling constant H , this is shown schematically in Fig.…”

Vacuum Ultraviolet Photodissociation Branching Ratios of 12C16O, 13C16O, and 12C18O from 100500 to 102320 cm–1

“…In the recent photoabsorption study by Eidelsberg et al, the state at ∼102311 cm –1 was reassigned as the high vibrational level (υ′ = 5) of the E­(3pπ) 1 Π state. Lefebvre-Brion and co-workers have recently performed a series of theoretical calculations, the potential energy curves of CO and their mutual interactions, especially the Rydberg–Rydberg and Rydberg-valence types of 1 Π– 1 Π, 1 Π– 3 Π, and 3 Π– 3 Π interactions, in the energy range below ∼105000 cm –1 have been relatively well constructed. ,− According to these theoretical calculations, the states at ∼100650 cm –1 and ∼102311 cm –1 were assigned to the υ′ = 1 and 2 levels of the valence E′ 1 Π state, respectively, which strongly interacts with the Rydberg E 1 Π state. , The well-constructed potential energy curves make a tentative discussion of the detailed predissociation pathways of CO in the aforementioned energy range possible.…”

“…Since the year of 2007, Lefebvre-Brion and co-workers have performed a series of ab initio calculations on the potential energy curves of CO, and special attention have been paid to the valence 1 Π and 3 Π states and their interactions with the Rydberg states. ,− Thanks to all these theoretical efforts, the predissociation pathways involving 1 Π– 1 Π and 1 Π– 3 Π interactions of Rydberg-valence type in the relatively low energy region (mainly below the second dissociation threshold C­( 1 D) + O­( 3 P)) have been gradually unraveled. The isotope dependent accidental predissociation processes in the low vibrational levels of the E 1 Π state, which involve the interactions with the valence E′ 1 Π and k 3 Π states, have been very well explained. ,, They correctly reproduced the rotational dependent predissociation line widths of the two interacting levels, W­(3sσ) 1 Π­(υ′ = 1) and the second valence 1 Π state E′ 1 Π. , The good agreements above between theory and high-resolution spectroscopic measurements confirm the accuracy of the potential energy curves of CO so far obtained in the energy region below the second dissociation threshold C­( 1 D) + O­( 3 P).…”

“…Photodissociation branching ratio measurements can provide more information about the predissociation process than pure spectroscopic methods do, since the branching ratios are determined not only by interactions in the Franck–Condon region, but also by interactions that are far away from the Franck–Condon region. The predissociation process of the W­(3sσ) 1 Π­(υ′ = 1) state is a good example as presented in refs and . Only considering the interactions of the W­(3sσ) 1 Π­(υ′ = 1) state with the valence E′ 1 Π state can very well reproduce the predissociation line widths, while with the same coupling parameters the branching ratios of the W­(3sσ) 1 Π­(υ′ = 1) state cannot be explained at all, and this issue can only be solved through refining the strength of the nonadiabatic interaction between the k 3 Π and 4 3 Π states at a nuclear distance of ∼3.5 au (see Figure 2 in ref ), which is already out of the Franck–Condon region …”

“…The predissociation process of the W­(3sσ) 1 Π­(υ′ = 1) state is a good example as presented in refs and . Only considering the interactions of the W­(3sσ) 1 Π­(υ′ = 1) state with the valence E′ 1 Π state can very well reproduce the predissociation line widths, while with the same coupling parameters the branching ratios of the W­(3sσ) 1 Π­(υ′ = 1) state cannot be explained at all, and this issue can only be solved through refining the strength of the nonadiabatic interaction between the k 3 Π and 4 3 Π states at a nuclear distance of ∼3.5 au (see Figure 2 in ref ), which is already out of the Franck–Condon region …”