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Experiments directed toward elucidating the nature of fragments produced by the photodissociation of ClN3 have been performed. The utlraviolet absorption spectrum of this molecule exhibits three features between 300 and 170 nm, with λmax = 250, 205, and <170 nm. The shortest wavelength feature (whose maximum was not resolved) was the strongest of the three, with ε170 = 5000 ℓ mol−1 cm−1. Photolysis of ClN3 at 193 nm produces N2 and NCl fragments in both the singlet and triplet manifolds. In the singlet manifold of fragments, emission from electronically excited NCl(b 1Σ+) was observed. The NCl(b 1Σ+) molecules are also vibrationally excited, and emission from levels as high as v′ = 10 was recorded. Time resolution of the NCl(b 1Σ+) emission indicated that the higher vibrational levels were quenched by the gas mixture (∼3% ClN3 in helium) much more rapidly than the lower vibrational levels. The rate constant for quenching of the low v′ levels (v′ = 0–2) of NCl(b 1Σ+) was determined to be kQ = (1.72±0.05)×103 s−1 Torr−1; the rate constant for quenching of the higher levels (v′?8) was found to be kQ = (3.8±0.2)×104 s−1 Torr−1. The spontaneous emission rate for NCl(b 1Σ+), v′ = 0–2, was measured to be A = 1590±160 s−1. In the triplet manifold of fragments, photolysis at 193 nm produces excited N2(A 3Σ+u) metastable molecules. The presence of this species was determined from the observation of N2(C 3Πu)→(B 3Πg) emission produced by energy pooling processes, and from the excitation of NO by energy transfer from the N2 metastables. Photolysis of ClN3 produces at 193 nm excited singlet and triplet fragments with comparable probability. Photolysis at 249 nm also generates both excited singlet and triplet NCl and N2 fragments. Emission from vibrationally excited NCl(b 1Σ+) was again observed, and the initial vibrational distribution appeared to be similar to that found for photolysis at 193 nm. The yields for production of NCl(b 1Σ+) at 193 and 249 nm are approximately equal. Photolysis at 249 nm also produces N2(A 3Σ+u) fragments, although in substantially smaller yield than found at 193 nm.

The gas-phase microwave spectrum of 1-pentyne has been investigated in the region 8–40 GHz. The spectrum can be attributed to two rotational isomers in which the methyl group is, respectively, trans and gauche to the acetylene substituent. The rotational constants of the trans form are A = 23 340 ± 200, B = 2230.566 ± 0.020, and C = 2116.385 ± 0.020 MHz, and those for the gauche form are A = 9921.112 ± 0.030, B = 3172.780 ± 0.010, and C = 2634.025 ± 0.010 MHz. From these data a plausible structure has been derived which gives the gauche dihedral angle as 115° ± 3° from the trans position. For each form several vibrationally excited states have been assigned to the torsional motion around the central carbon—carbon bond, the methyl internal rotation, and the C–C≡C bending motion. The torsional vibration frequency is 106 ± 10 cm−1 in the trans form and 114 ± 10 cm−1 in the gauche. Stark effect measurements yield μ trans = 0.842 ± 0.010 D and μ gauche = 0.769 ± 0.028 D. The gauche-form ground state is 27 ± 36 cm−1 below the trans ground state. Four coefficients in the Fourier expansion of the potential energy for rotation about the central C–C bond have been derived: V1=0.940, V2=−1.045, V3=3.518, and V4=0.071 kcal/mole. It is suggested that the slightly greater stability of the gauche form may be due to an attractive dipole—dipole interaction.

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Charge exchange and hydrogen atom pickup cross sections, and product ion time-of-flight measurements are reported for N+2 –H2O(D2O) collisions at center-of-mass collision energies ranging between 1 and 15 eV. No isotope effect is detected for the charge exchange branch, while a significant isotope effect is observed for the atom pickup reaction. Throughout the measured energy range, the time-of-flight measurements show that the H2O+(D2O+) charge exchange product is produced with near-thermal energy in the laboratory frame, implying little or no momentum transfer. The charge exchange reaction products are therefore formed with internal energy comparable to the exothermicity of the reaction (2.96 eV). The atom pickup ion product velocity distributions and the atom pickup isotope effect are consistent with a spectator stripping mechanism.