I don't know which line gets excited, but a good clue would be to look at an Argon light. If you heat it enough to spark, of course, it's ultraviolet.

By looking for information to answer to your question, I found out that when a flow of electrical current passes through argon gas, several wavelengths of light are produced, including short-wave ultraviolet light. However, it would be interesting to try to see it through an experiment.