Research group led by Prof. YUAN Kaijun and Prof. YANG Xueming from the   Dalian Institue of Chemical Physics (DICP) of the Chinese Academy of Sciences, with the help of powerful any user-selected VUV wavelength laser output capability of Dalian Coherent Light Source revealed the photochemical rationale of SH(X)/H   ₂S abundance ratios in interstellar medium. The results were published in   Nature Communications.

 

H2S is regarded as the priority product when the sulfur atoms impinging on interstellar ice mantles, due to the high-hydrogen abundances and the mobility of hydrogen in the ice matrix, early analyses from measurements of interstellar SH radicals using the GREAT instrument on SOFIA returned SH /H   ₂S abundance ratio of ~13% , which was very small than predicted by commonly used astrochemical models.  
 

 
SH radical production  in H   ₂S ultraviolet photolysis measured by DCLS photodissociation dynamics experimental station (Image by ZHAO Yarui, ZHOU Jiami)

 

The work revealed only ~26% of photoexcitation events result in SH(X) products by convoluting the wavelength dependences of quantum yield for forming SH(X) products, the H   ₂S parent absorption and the interstellar radiation ？eld, the results indicate the three-body dissociation is an inevitable source of SH(X) radical depletion, which need to be added into the related astrochemical models.

 

This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the Chemical Dynamics Research Center, and the National Natural Science Foundation of China. (Text by ZHAO Yarui, ZHOU Jiami)