Using the output of one dye laser as the fundamental wave,we have generated tunable VUV coherent radiation from 116.6nm through 119.2nm by nonresonant four-wave sum-mixing process below the first resonance level of Ne.The conversion efficiency was found to be comparatively high because of the very small dispersion in this range.We found that the four-wave sum-mixing output was proportional to the square of the gas density we offered.If we increase the gas density of Ne,the conversion efficiency is estimated to be improved by two orders.