Multiple pulse sequences are widely used for signal enhancement in NQR detection applications. Since the various 14 N NQR relaxation times, signal decay times and frequency of each NQR line have a major influence on detection sequence performance, it is important to characterise these parameters and their temperature variation, as fully as possible. In this paper we discuss such measurements for a number of the ν + and ν − NQR lines of monoclinic and orthorhombic TNT and relate the temperature variation results to molecular dynamics. The temperature variation of the 14 N spin-lattice relaxation times T 1 is interpreted as due to hindered rotation of the NO 2 group about the C-NO 2 bond with an activation energy of 89 kJ mol -1 for the ortho and para groups of monoclinic TNT and 70 kJ mol -1 for the para group of orthorhombic TNT.