N-m-tolyl phthalimide, C₁₅NO₂H₁₁ crystallizes in the space group Cc with unit cell dimensions,a=8·54(1),b=19·89(2),c = 7·59(1)A, β=114·53(1)° andZ=4.V=1173(2)A³,D_m=1·35(1),D_c = 1·344 mg.m⁻³,M_r=237 λCoK_a=1·7903A. The structure was solved byMULTAN and refined to an R-factor of 0·116 for 632 counter reflections. The molecules are held together by van der Waal’s forces. The angle between the tolyl plane and the plane through the phthalimide group is 53·4(4)°.

The multiple-quantum pathway description developed earlier for two-dimensional single-quantum correlation spectroscopy (cosy), is generalized and applied to the two-dimensional multiple-quantum transitions (2Dmqt) spectroscopy. The connectivity classes ofcosy are also generalized tomqt spectroscopy. The pathway description allows a straightforward method of computation of the flip angle dependence of the intensity of various peaks in two-dimensional correlation spectroscopy. It is shown that a variation of flip angle allows distinction between various classes and types of transitions, as well as optimization of experiment for selective detection of certain classes of peaks in 2D spectroscopy.

Rotation-free transmission measurements governed by ground-state recovery of coumarin 102, coumarin 138 and coumarin 339 dyes in ethanol solutions were performed for the first time by pump-probe technique using 35 ps pulses of Nd:YAG laser at 355 nm. Recovery of absorption is characterized by simple exponential behaviour with relaxation times of 4.0, 3.7 and 3.0 ns respectively for C 102, C 138 and C 339. These values are comparable to the lifetimes of the first excited singlet states.

The time-resolved laser emission of coumarin 102 was investigated in various aprotic and protic solvents at picosecond resolution by frequency upconversion technique. The spectral shift of the transient emission spectrum is attributed to solvent reorientation and the results are discussed.