Photodissociation Dynamics of D₂S⁺ near 340 nm^†

The photodissociation dynamics of polyatomic molecules is of great significance for the analysis of molecular potential energy surfaces and dissociation product channels. We studied the photodissociation dynamics of D₂S⁺ in the ultraviolet region using the time-sliced velocity map ion imaging technique. The images of S⁺ products were measured at photodissociation wavelengths around 340 nm. From these images, the total kinetic energy releases of the product, branching ratios, and angular distributions were derived. We found that the total kinetic energy releases and the angular anisotropy parameters of products generally showed similar characteristics. The D₂ products are populated in v = 0 and v = 1 vibrational states, and the D₂ (v =0) is predominantly populated at all the photolysis wavelengths. The angular distributions of S⁺ products are nearly isotropic at the photolysis wavelengths ranging from 340.10 nm to 340.34 nm. However, at the photodissociation wavelength of 340.39 nm, the angular distributions of S⁺ products were anisotropic. The change of angular distributions may result from different dissociation mechanisms involving nonadiabatic coupling and contribute to the final dissociation channel. This work provides a further understanding in the ultraviolet photodissociation dynamics of D₂S⁺ and more information on the isotopic effect for the photodissociation of the H₂S⁺ cation.