15N Spin Lattice Relaxation in Liquid 15NH3 and 15ND3

The spin‐lattice relaxation times (T₁) for ¹⁵N in ¹⁵NH₃ and ¹⁴ND₃ have been determined and are presented and discussed. The magnitudes and temperature dependences of T₁ for ¹⁵NH₃ and ¹⁵ND₃ indicate that spin‐rotational and intramolecular dipolar interactions together dominate the ¹⁵N relaxation in ¹⁵NH₃. Since ${\gamma }_{\mathrm{D}}{\text{≈ 0.15\hspace{0.17em}γ}}_{\mathrm{H}}$ , the dipolar term is small compared with the spin‐rotational term in ¹⁵ND₃ at room temperature. This allows one to separate the spin‐rotational and dipolar contributions in ¹⁵NH₃. Values of τ_c, τ_sr, and C_N are then derived from the experimental data for ¹⁵NH₃ and compared with values derived in other work.