New vibronic bands were observed in the 17000-17600cm - 1 region by laser induced fluorescence (LIF) spectroscopy in the discharged products of a mixture of C 2 H 2 and CS 2 in a supersonic jet. The effective rotational constants and the position of the vibronic band origin have been determined to be B'' e f f =0.01910(2)cm - 1 ,B ' e f f =0.01891(2)cm - 1 , and T 0 =16961.5161(5)cm - 1 , respectively. The spectral carrier of the bands has been confirmed to be the HC 6 S radical from the chemical behavior of the products and the determined rotational constant.