Several isotopes of NH
3have been studied as laser candidates, including ND
2H, NH
2D, ND
3, and N
15H
3. Lasing was observed in N
15H
3at 15.08 and 15.91 μ. Tentative assignments of transitions to the

vibrational levels have been made. Enhanced energy output was observed in N
14H
3with the addition of helium.