The electronic absorption spectra of thiophen and of some deuterated thiophens have been studied in the range 2500-14OOA. Three electronic transitions, with origins at 41 595, 48 330 and 53 270 cm-' in C4H4S and two Rydberg series leading to the limit 71 570 cm-I were analyzed. The broadness of the bands prevents the identification of the symmetry of the upper states by analysis of band contours. Only progressions of totally-symmetric vibrations appear in the vibrational structure of the first three transitions, indicating that they are allowed. From the small changes of the vibrations in respect to the ground state, and from the intensity distribution in the vibrational structure, it can be concluded that the geometry of the Rydberg states is close to that of the ground state.* Vibrational frequencies are numbered as recommended by Mulliktm.lz

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Second and third overtones of N-H stretching vibration in HN3 have been investigated at higher rcsolving power and pathlength than previously, and the fourth overtone photographed for the first time. The rotational analysis of 3v1, where more than 500 lines were measured, gives accurate values of the rotational constants of both ground and upper states. A local perturbation was found in levels with K' = 2 and 4. The rotational analysis of 4v1, where lines are broader than in 3vl, indicates that the dependence of A from vibrational quantum number ul, is not linear. Owing to the large linewidth (-0.35 cm-') only the analysis of the K-structure is possible for 5vl. The diffuseness in 4vl and 5vl is discussed in terms of line broadening by case I1 predissociation.

The rotational fine structure of the 3ul and vL2 vibrations of pyrrole (C4HJN) have been recorded at 0.98 and 14 pm respectively. About 100 lines were measured in the 3 v , and 120 in the v22 Rand 1'-branches. The analysis of the resolved fine structure and of the Q-branch contour yielded the following molecular constants (all in cm-I): A' = 0.304 5 , B' = 0.298 5, C' = 0.151 22, v0 = 10 184.174 for 3 u l , and B' = 0.301 4, vo = 722.21 for v z Z . The rotational levels of 3u1 with 35 < J < 4 5 are perturbed and the fine structure is either weak or not observed in this range of J-values.