VUV photodissociation of DNCO: dynamics of the D atom elimination channel

Abstract

The D atom Rydberg tagging time-of-flight technique was applied to investigate the photodissociation dynamics of DNCO in the vacuum ultraviolet 133–137 nm region. The D atom product was detected and the corresponding product translational energy distributions and angular distributions were obtained. Three product channels, D + NCO(X²Π), D + NCO(A²Σ⁺) and D + NCO(B²Π), which arise from different dissociation pathways have been observed. It is found that the D + NCO(X²Π) channel involves two different dissociation pathways; one is via internal conversion from the excited state to the S₀ state, and the other is via internal conversion from the excited state to the S₁ state. The D + NCO(A²Σ⁺) channel was ascribed to be from dissociation on S₂ surface, and the D + NCO(B²Π) channel possibly come from a relatively slow dissociation process. Vibrational structures observed in the D + NCO(A²Σ⁺) channel shows that there is dominant bending with a little stretching vibrational excitation of NCO(A²Σ⁺). This is consistent with what has been found in the previous study following VUV photodissociation of HNCO in a similar wavelength region.

GRAPHICAL ABSTRACT

KEYWORDS:

• Vacuum ultraviolet
• photodissociation dynamics
• isocyanic acid (HNCO)
• Rydberg tagging time-of-flight spectroscopy

Acknowledgements

This work was supported by the National Key R&D Program of China, (grant number 2016YFF0200500), the National Natural Science Foundation of China (Grant Nos. 21922306 and 21590802), the Strategic Priority Research Program of Chinese Academy of Sciences (grant number XDB17000000).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Key R&D Program of China [grant number 2016YFF0200500], the National Natural Science Foundation of China [grant number 21922306], [grant number 21590802], the Strategic Priority Research Program of Chinese Academy of Sciences [grant number XDB17000000].