We know transitions to the n = 1 state are in the UV (the Lyman series) and to the n = 2(the Balmer series) lies in the visible. Therefore, I would suggest you start with a transition ending in N=3 and starting with N = 4 and see how that works. You want the wavelength to come out larger than about 700 nm. (700-800 nm is the start of the near infrared and anything above 1,000 nm to 2,000 nm is infrared.
