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Both positive and negative ions of N3O2 have been observed in various experiments. The neutral N3O2 was predicted to exist either as a weakly bound NO·N2O complex or a covalent molecule. The rovibrational spectrum of the NO(X2Π)–N2O complex has been measured for the first time in the 5.3 µm region using distributed quantum cascade lasers to probe the direct absorption in a slit-jet supersonic expansion. The observed spectrum is analyzed with a semi-rigid asymmetric rotor Hamiltonian for a planar open-shell complex, giving a bent geometry with an a-axis–NO angle of about 21.9°. The vibrationally averaged 2A′–2A″ energy separation is determined to be ε = 144.56(95) cm−1 for the ground state, indicating that the electronic orbital angular momentum is partially quenched upon complexation. Geometry optimizations of the complex restricted to a planar configuration at the RCCSD(T)/aug-cc-pVTZ level of theory show that the 2A″ state is more stable than the 2A′ state by about 110 cm−1 and the N atom of NO points to the central N atom of N2O at the minimum of the 2A″ state. [ABSTRACT FROM AUTHOR]

The rovibrational spectrum of the Ne–NO(X2Π) open-shell complex has been measured in the 5.3 µm region using distributed feed-back quantum cascade lasers to probe the direct absorption in a slit-jet supersonic expansion. Three P-subbands (P′ ← P″: 1/2 ← 1/2, 3/2 ← 1/2, and 5/2 ← 3/2) were observed, where P is the projection of the angular momentum J along the inertial a-axis of the complex. The hyperfine structure due to the nuclei spin of 14N (I = 1) was partially resolved in the P′ ← P″: 1/2 ← 1/2 and 3/2 ← 1/2 subbands. The observed mid-infrared spectrum of Ne–NO (X2Π) together with the previously reported microwave spectrum was analyzed using a modified semirigid asymmetric rotor Hamiltonian for a planar open-shell complex. The band origin is located at 1876.0606(97) cm−1, which is blue-shifted from that of the NO monomer by only 0.0888 cm−1. The complex shows strong structural relaxation upon excitation of the overall rotation and the internal rotation of the NO subunit. [ABSTRACT FROM AUTHOR]

The rovibrational spectrum of the Ar–NO open-shell complex has been measured in the 5.3 µm region using distributed feed-back quantum lasers to probe the direct absorption in a slit-jet supersonic expansion. Five P-subbands, namely, P ′ ← P ″ : 1 / 2 ← 3 / 2,1 / 2 ← 1 / 2,3 / 2 ← 1 / 2,5 / 2 ← 3 / 2 , and 7 / 2 ← 5 / 2 , are observed, with J up to 15.5. The hyperfine structure due to the nuclei spin of 14N (I = 1) can be partially resolved in the P ′ ← P ″ : 1 / 2 ← 3 / 2,1 / 2 ← 1 / 2 , and 3 / 2 ← 1 / 2 subbands. The fine structure of the observed spectrum is analyzed using a modified semi-rigid rotor Hamiltonian [W. M. Fawzy and J. T. Hougen, J. Mol. Spectrosc. 137, 154–165 (1989)] and an empirical Hamiltonian [Y. Kim and H. Meyer, Int. Rev. Phys. Chem. 20, 219–282 (2001)] separately. The hyperfine structure can be simulated successfully by including hyperfine terms to the semi-rigid rotor Hamiltonian. A linear J-dependence of the angle between the inertial a-axis of the complex and the intramolecular axis of the NO subunit is also introduced in order to model the strong structure relaxation effect in the P = 1/2 state. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rovibrational spectra of nonpolar (N 2 O) 2 and Ar-N 2 O complexes in N 2 O monomer 2 v 2 band region are measured and analyzed. • Vibrational frequencies and infrared intensities of fundamental, overtone and combination bands are calculated. • Accurate molecular constants for both ground and excited vibrational states are derived. Rovibrational spectra of Ar–N 2 O and nonpolar (N 2 O) 2 van der Waals complexes have been recorded from 1157.2 to 1176.7 cm−1 in 2 v 2 overtone band region of N 2 O monomer using an external-cavity quantum cascade laser to probe the direct absorption in a slit supersonic jet expansion. One a / b hybrid vibrational band was identified for nonpolar (N 2 O) 2 , and one b -type vibrational band for Ar–N 2 O, respectively. Quantum chemical calculations of vibrational frequencies and infrared intensities of these two complexes were performed at the MP2/aug-cc-pvtz level of theory. The first vibrational band is assigned tentatively as a combination band of the intramolecular symmetric and anti-symmetric in-plane bending modes of nonpolar (N 2 O) 2. The second vibrational band is assigned as an overtone band of the bending mode of Ar–N 2 O. Precise molecular constants have been derived for these two complexes. The band-origin is located at υ 0 = 1168.177584(76) cm−1 for Ar–N 2 O and υ 0 = 1165.218580(54) cm−1 for nonpolar (N 2 O) 2 , which shows a blue-shift by 0.0451 cm−1 for Ar-N 2 O and a red-shift by 2.9139 cm−1 for nonpolar (N 2 O) 2 compared with that of the N 2 O (0200)-(0000) band, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rovibrational spectra of (SO 2) 2 and Ar-SO 2 complexes in SO 2 monomer v 1 band region are measured and analyzed. • Accurate molecular constants for both ground and excited vibrational states are derived. • Tunneling splitting and Coriolis coupling constant of Ar-SO2 in excited vibrational states are determined. Rovibrational absorption spectra of Ar–SO 2 and (SO 2) 2 van der Waals complexes generated in a slit supersonic jet expansion have been recorded in the v 1 symmetric stretching region of SO 2 monomer using an external-cavity quantum cascade laser. Two vibrational bands for (SO 2) 2 and one for Ar–SO 2 are assigned and analyzed. All these vibrational bands are of a / c hybrid type. The observed infrared transitions are fitted together with previous radio frequency and microwave spectra, yielding precise molecular constants in both the ground and excited vibrational states for these two complexes. The band origins of (SO 2) 2 are determined to be 1150.30319(13) cm−1 for vibration on the electron-donor side and 1153.40911(10) cm−1 for vibration on the electron-acceptor side, which is shifted from that of the SO 2 v 1 band by about −1.41 cm - 1 and + 1.70 cm−1, respectively. The vibrational energies of the two tunneling components of Ar–SO 2 are determined to be 1151.61315(11) cm−1 and 1151.64840(11) cm−1. The tunneling splitting of Ar–SO 2 increases from 982.881(32) MHz in the ground state to 1056.7(34) MHz in the excited vibrational state, indicating a decrease of the tunneling barrier upon excitation of the SO 2 symmetric stretching vibration. [ABSTRACT FROM AUTHOR]