[en] We measured the vibrational-rotational line profiles of ¹⁴N ¹⁶O and ¹⁵N ¹⁶O in the electronic transition spectrum by using the magnetically scanned ion line of ¹¹⁴Cd(II) at 2165.017 A. The observed separation between the line of ¹⁴N ¹⁶O, Q[10(1/2)] and the line of ¹⁵N ¹⁶O, Q₂[11(1/2)] was 49.6 GHz, and the half-width of these lines was 4.4 GHz. We could observe the line profile of ¹⁵N ¹⁶O in naturally occurring NO, even though its abundance is 0.37%. Also, the ratio ¹⁵N/¹⁴N in nitric acid was determined with this technique. The lower detection limit was about 50 ppb