DETECTION OF HSNO, A CRUCIAL INTERMEDIATE LINKING NO AND H2S CHEMISTRIES

The simplest S-nitrosothiol, thionitrous acid (HSNO), is a reactive molecule of both biological and astronomical interest. Here we report the first detection of both textit{cis}- and textit{trans}-HSNO by means of Fourier-transform microwave spectroscopy and double resonance experiments. Surprisingly, HSNO is readily produced in a gas expansion of H$_2$S and NO, i.e. without applying any discharge. Once formed, HSNO appears quite stable, as evidenced by its high steady-state concentration. A precise empirical molecular equilibrium structure was derived from a combination of theory and experiment