The Photodissociation Dynamics Of CS2 In The UV Region

Carbon disulfide(CS2)is a trace component of stratosphere and troposphere,which plays a significant role in the study of astrochemistry.CS2 molecules are the important precursor in the atmospheric sulfur cycle as a three-atom sulfur-containing compound.The photodissociation process in the atmosphere is a main sink of CS2.The radicals such as CS produced in this process are actively involved in various chemical reaction.As a result,it is important to study the photodissociation dynamics of CS2.We studied the photodissociation of CS2 at near 204nm using the velocity map ion imaging technique.A complete,clear experimental image were obtained,which is beneficial in understanding the dissociation mechanism of the channels.A UV and a VUV laser beams were employed in this experiments.The UV laser light was used to photolysis CS2 molecules.And the tunable VUV detection laser was generated using the difference four wave mixing method.In addition,an off-axis MgF2 biconvex lens is used between the mixing cell and the cavity to disperse the beams,so that only a VUV detection light can enter the reaction center,which greatly improves the signal-to-noise ratio of the experiment.The S(3P)and S(1D2)channels were detected by different methods at five specific photolysis wavelengths around 204nm.High-resolution raw images were measured by state selection detection.The CS fragments with different vibrational states can be distinguished.Then,the total kinetic energy distributions,branching ratios and angular distribution of products are derived.Both channels have smaller anisotropy parameter values,which indicates that they both come from the indirect predissociation process of CS2.The result is completely consistent with the previous conclusion.At several specific wavelengths,the total kinetic energy distributions and angular distributions are uniform and similar,which suggest that they have similar dissociation mechanism within this range.The non-adiabatic coupling plays an important role in the process of CS2 dissociation.