Rotational dependence of the branching ratios and fragment angular distributions for the photodissociation of ¹²C¹⁶O in the Rydberg 4p(2) and 5p(0) complex region (92.84–93.37 nm)

Abstract

Various patterns of rotational dependence for the photodissociation branching ratios and irregular angular distributions of the photofragments have been observed.

Photodissociation branching ratios of 13C16O and 12C18O in the vacuum ultraviolet region from 107 800 to 109 700 cm−1

“…Besides the rotation-dependent photodissociation, we also see photodissociation that is independent of both rotation and parity, which implies that homogeneous interaction with a 1 Π state is also involved in the predissociation process of this state. Similar phenomena have been observed previously for many 1 Π states of CO (Gao et al 2013;Jiang et al 2019aJiang et al , 2020Chi et al 2020b).…”

“…The dotted box indicates the energy range investigated in the current study. The X-axis shows -1-branching ratios from Gao et al (2013), Chi et al (2020b); -2-branching ratios from Shi et al (2018), Jiang et al (2019aJiang et al ( ,b, 2020; and -3-branching ratios from Gao et al (2011Gao et al ( , 2012, Chi et al (2020a) current study. e/f parity was noted, probably because only branching ratios of J < 4 levels were measured.…”

“…7. This might be due to the different molecular beam temperatures generated by the Even-Lavie valve and the general valve (Jiang et al 2019a). The simulated spectrum generated using PGOPHER is presented in red in Fig.…”

“…A37, page 11 of 13 A&A 637, A37 2020So far, the photodissociation branching ratios of the vast majority of strong absorption bands of 12 C 16 O and 13 C 16 O in the VUV region from 102 807 cm −1 (97.27 nm) to 109 700 cm −1 (91.16 nm) that are of astrophysical interest, as listed in Table 1 by Visser et al (2009), have been measured and documented (Gao et al 2011(Gao et al , 2012(Gao et al , 2013Shi et al 2018;Jiang et al 2019aJiang et al ,b, 2020Chi et al 2020b,a). Extension of the measurements for 12 C 18 O in the lower energy region from 102 807 cm −1 (97.27 nm) to 107 816 cm −1 (92.75 nm) is in progress.…”

“…Since 2011, significant progress has been made toward systematically determining the quantum state populations of the atomic photodissociation products of 12 C 16 O and its isotopologs using a time-slice velocity-map imaging (TSVMI) setup and a tunable VUV laser radiation source produced by the twophoton resonance-enhanced four-wave mixing scheme. Jackson, Ng, Gao, and coworkers (Gao et al 2011(Gao et al , 2012(Gao et al , 2013Shi et al 2018;Jiang et al 2019a;Chi et al 2020a) measured and documented all strong 12 C 16 O absorption bands in the VUV region from 102 807 cm −1 (97.27 nm) to 109 700 cm −1 (91.16 nm) that are of astrophysical importance as listed in Table 1 by Visser et al (2009). Collectively, these findings show that the photodissociation products are formed not only in the ground state, but also in the excited states in substantial amounts.…”