Mid-Infrared Spectroscopy Of Van Der Waals Complexes Containing N₂O

Intermolecular force plays a key role in many fields of physics, chemistry and life science such as phase transition, surface adsorption or desorption, and protein folding. The study of the spectrum, structure, and dynamic of Van der Waals complexes is an important way to understand the nature of intermolecular force. Nitrous oxide (N2O) is an important trace gas. The accurate description of the interaction between N2O and atoms or molecules has been the significant subject of quantum chemistry and molecular spectroscopy. In this paper, several Van der Waals complexes were investigated using an infrared tunable diode laser spectrometer with a supersonic slit jet expansion. The following is the main results:1. The infrared spectrum N2O-Ne was investigated in the N2O v1 symmetric stretching region. Forty-three and twenty-two transitons were measured and assigned for 20Ne-N2O and 22Ne-N2O, respectively. With the molecular constants of ground state and high-level centrifugal distortion constants of excited fixed at the literature values, the other parameters of excited state for these complexes were determined via the least square fit.2. The rovibrational spectra of four isotopomers of the Kr-N2O van der Waals complex, namely 82Kr-N2O,83Kr-N2O,84Kr-N2O and 86Kr-N2O, were measured in the same region. The molecular constants for both ground and excited states of these four isotopomers were accurately determined by the least square fit. The band-origin shifts of N2O-Rg (Rg=Ne, Ar, Kr) in the v3 vibrational band region were found to be also well explained by the model based on a Buckingham intermolecular potential. But the band origin shift of He-N2O was found to deviate significantly from this model.3. The rovibrational spectrum of N2-N2O was observed in the N2O symmetric stretching region. One hundred and fifty-two transitions of this complex were measured and assigned. The rotational and centrifugal distortion constants for the ground and excited vibrational states were accurately determined. A two-dimensional intermolecular potential energy surface for a planar structure of N2-N2O has been calculated at the CCSD(T) level of theory with the aug-cc-pVDZ basis sets. With the intermolecular distance fixed at the ground state value R=3.6926A, the potential has a global minimum with a well depth of 326.64 cm-1 atθN2=11.0°andθN2O=84.3°4. The rovibrational spectra of (N2O)2 dimer and (N2O)3 trimer were observed in the N2O symmetric stretching region. Some transitions with higher quantum number were measured and analyzed in this region. The energy levels of N2O dimer with Ka’=9,10 were found to have the similar perturbation as Ka’= 0,1. As to (N2O)3, an extensive analysis for this trimer was given in the 1285 cm-1 region and 55 new transitins were assigned. The molecular constants of ground and four excited states were obtained through a globe fit, the precision of some canstants has a bit improved.