Recent observations by the Cassini Orbiter suggest that complex organic chemistry occurs in the upper atmosphere of Titan. To understand the role of EUV-VUV light in the complex organic chemistry of Titan's upper atmosphere, we investigate the formation of gaseous species from a N₂/CH₄ gas mixture as a function of irradiation wavelengths from 50 nm to 150 nm. A N₂/CH₄ gas mixture (= 95/5) at 0.066 mbar in a windowless photocell is irradiated using a narrowband synchrotron radiation source. The analysis of gaseous products by quadrupole mass spectrometry reveals the formation of heavy organics up to C₇ to C₈ by EUV light irradiation. In particular, the efficient formation of benzene and toluene is observed at wavelengths less than 80 nm, which is well correlated to photoionization of N₂. In Titan's upper atmosphere, EUV radiation may play an important role in the formation of complex organic molecules through photoionization of N₂.