G. Galloni

The ν1 and 3ν1 bands of HNCO

Abstract The infrared absorption of HNCO has been measured in the region of the NH stretching fundamental and in that of the second overtone. The results for the excited states are (in cm−1): Band ν 0 A- B B C ν 1 3533.1 27.0 — — 3ν 1 10145.79 22.6713 0.368426 0.361722 Ground state term values F(0, K) up to K = 8 were determined from millimeter wave, far infrared, and present data.

Infrared spectrum and vibrational potential function of thionylimide (HNSO)

Abstract The ir absorption of gaseous HNSO, DNSO and H15NSO is recorded in the range 300–4100 cm−1 at medium resolution. Besides the fundamental vibrations, overtones and combination bands are measured and assigned. From these data, combined with the ir absorptions of four more isotopic species of thionylimide, and with the centrifugal distortion constants of HNSO and DNSO, a harmonic force field, with 11 constants was derived.

Rotation-vibration spectrum of hydrazoic acid in the near infra-red and in the visible

Second and third overtones of N—H stretching vibration in HN3 have been investigated at higher resolving power and pathlength than previously, and the fourth overtone photographed for the first time. The rotational analysis of 3ν1, 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 4ν1, where lines are broader than in 3ν1, indicates that the dependence of A from vibrational quantum number v1, is not linear. Owing to the large linewidth (∼0.35 cm–1) only the analysis of the K-structure is possible for 5ν1. The diffuseness in 4ν1 and 5ν1 is discussed in terms of line broadening by case II predissociation.

Electronic spectrum of thiophen and some deuterated thiophens

The electronic absorption spectra of thiophen and of some deuterated thiophens have been studied in the range 2500–1400 A. Three electronic transitions, with origins at 41 595, 48 330 and 53 270 cm–1 in C4H4S and two Rydberg series leading to the limit 71 570 cm–1 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.

Molecular spectra of OCSe

The absorption spectra of OCSe vapour have been recorded in the i.-r. (300–5000 cm–1) and u.-v. (2600–1350 A) regions. Several electronic transitions were identified, which always display progressions in ν′3 and possibly ν′1, except the first transition at 4.89 eV, where ν′2 is active: this absorption has been assigned to a bent-linear trasition. An upper limit to the dissociation energy of OC—Se bond (3.1 eV) was obtained from linear extrapolation of the ν′3 progression of the second transition at 5.83 eV.

The ν1 progression of HNSO in the ground state

Abstract The infrared spectrum of HNSO has been observed in the region of the NH stretching fundamental and in those of the first and second overtones. The main results (in cm−1) for the excited states are: Band ν 0 A B + C B − C ν 1 3308.50 1.6339 0.6027 0.0541 2ν 1 6463.56 1.6222 0.6018 3ν 1 9465.04 1.6149 Ground state rotational and centrifugal distortion constants were determined from microwave data of Kirchhoff (1) with combination differences from the infrared measurements.

The ν1 and 2ν1 bands of DNSO

Abstract The infrared spectrum of DNSO has been recorded in the region of the N-D stretching fundamental vibration and of the first overtone. The results of the analysis are the following (in cm −1 ): State ν 0 A B C v 1 = 1 2454.76 1.3982 0.3184 0.2588 v 1 = 2 4827.78 1.3866 It was also found that the anharmonicity constant x 11 can be predicted from x 11 of HNSO by the simple relation holding for diatomic molecules.

A- and C-type bands in the infra-red spectrum of pyrrole

The rotational fine structure of the 3ν1 and ν22 vibrations of pyrrole (C4H5N) have been recorded at 0.98 and 14 µm respectively. About 100 lines were measured in the 3ν1 and 120 in the ν22R- and P-branches. The analysis of the resolved fine structure and of the Q-branch contour yielded the following molecular constants (all in cm–1): A′= 0.304 5, B′= 0.298 5, C′= 0.151 22, ν0= 10 184.174 for 3ν1, and text-decoration:overlineB′= 0.301 4, ν0= 722.21 for ν22. The rotational levels of 3ν1 with 35 < J < 45 are perturbed and the fine structure is either weak or not observed in this range of J-values.

Franck-Condon distribution in the 226 nm band of trimethylene sulfide

Abstract The potential function for the ring-puckering vibration of trimethylene sulfide in the lowest excited singlet state is obtained, and the relative intensity distribution in the 226 nm electronic transition calculated. It is concluded that the excitation of the ring-puckering vibration by itself does not account for the intensity of the higher energy peaks that are better assigned as combination bands of ring-puckering and CS stretching modes.