Branching ratio measurements of the predissociation of 12C16O by time-slice velocity-map ion imaging in the energy region from 108 000 to 110 500 cm−1

Abstract

Direct branching ratio measurements of the three lowest dissociation channels of (12)C(16)O that produce C((3)P) + O((3)P), C((1)D) + O((3)P), and C((3)P) + O((1)D) are reported in the vacuum ultraviolet region from 108,000 cm(-1) (92.59 nm) to 110,500 cm(-1) (90.50 nm) using the time-slice velocity-map ion imaging and nonlinear resonant four-wave mixing techniques. Rotationally, resolved carbon ion yield spectra for both (1)Σ(+) and (1)Π bands of CO in this region have been obtained. Our measurements using this technique show that the branching ratio in this energy region, especially the relative percentages of the two spin-forbidden channels, is strongly dependent on the particular electronic and vibrational energy levels of CO that are excited.

Branching Ratio Measurements for Vacuum Ultraviolet Photodissociation of 12C16O

“…13,14 The product branching ratios in the predissociation of CO have been recently measured for the first time using this method in the energy region from 108 000 (13.390 eV) to 110 500 cm −1 (13.700 eV) 15,16 and were found to be strongly dependent on the vibronic states of CO that are excited. In the present study, we are extending these previous branching ratio measurements to the lower energy range from 102 500 (12.709 eV) to 106 300 cm −1 (13.180 eV).…”

Branching Ratios in Vacuum Ultraviolet Photodissociation of CO and N2: Implications for Oxygen and Nitrogen Isotopic Compositions of the Solar Nebula

“…The VUV induced predissociation of CO(X 1 Σ) leading to the formation of these product channels has not been examined in detail until recently (e.g., Okazaki et al 1998Okazaki et al , 2001Gao et al 2011aGao et al , 2012Gao et al , 2013aGao et al , 2013b. In the past, it was assumed that the ground state channel (4) dominates the photodissociation of CO in the VUV region because formation of the triplet dissociation channels (5) and (6) violates the Wigner electron spin conservation rule.…”

“…In the past, it was assumed that the ground state channel (4) dominates the photodissociation of CO in the VUV region because formation of the triplet dissociation channels (5) and (6) violates the Wigner electron spin conservation rule. Nevertheless, recent studies (Gao et al 2011a(Gao et al , 2012(Gao et al , 2013a(Gao et al , 2013b have reported evidence for the formation of the excited C(…”

“…Building on our recent comprehensive studies (Gao et al 2011a(Gao et al , 2012(Gao et al , 2013a(Gao et al , 2013b, we have completed a detailed investigation of the branching ratios of CO photodissociation induced by VUV excitation in the range of 11.09-13.60 eV (91.17-111.78 nm), using the time-slice velocity-map-imagingphotoion (VMI-PI) technique. The total O( 1 D) branching ratio in the CO predissociation is summarized in Table 1 and compared with the total N( 2 D) branching ratio in the N 2 predissociation in Table 2.…”

“…The branching ratios were measured using the VUV laser photodissociation-photoionization (PD-PI) time-slice VMI-PI apparatus, which has been described in detail previously (Gao et al 2011b(Gao et al , 2012(Gao et al , 2013a(Gao et al , 2013b. In this experiment, tunable photodissociation VUV laser radiation was generated by resonance-enhanced four-wave sum-frequency mixing (2ν 1 + ν 2 ) using a Xe gas jet as the nonlinear medium, where ν 1 and ν 2 represent the UV and visible laser frequencies, respectively.…”