High-Resolution Rovibrational Absorption Spectrum of CO₂−N₂O

Abstract

The rovibrational absorption spectrum of the weakly bound cluster CO 2 -N 2 O has been observed in the region of the ν 3 CO 2 asymmetric stretch (∼2350 cm -1 ). Clusters were formed by supersonic expansion of a mixture of N 2 O:CO 2 in a 4:1 ratio using He carrier gas. Approximately 340 lines have been assigned. Both parallel and perpendicular transitions were observed. The ground state rotational constants A, B, and C are 0.294 924-(12), 0.058 004(6), and 0.048 400(6) cm -1 , respectively. The quartic centrifugal distortion constants are D j ) 5.03(17) × 10 -7 cm -1 , D jk ) -3.92(9) × 10 -6 cm -1 , D k ) 1.26(2) × 10 -5 cm -1 , δ j ) 1.61(92) × 10 -8 cm -1 , and δ k ) 1.77(80) × 10 -6 cm -1 . Ab initio calculations for several CO 2 -N 2 O equilibrium structures have been done on the Hartree-Fock self-consistent field level using a 6-311g* basis set. Møller-Plesset MP2 and MP3 calculations were carried out for the two possible slipped parallel configurations of the dimer. The planar slipped parallel geometry with the oxygen atom of N 2 O nearest the CO 2 monomer was found to be the most stable structure. The spectral constants and stabilization energies were compared to those of the CO 2 and N 2 O homodimers. A planar slipped parallel geometry is observed with the O of N 2 O nearly over the C of CO 2 . R cm and θ are 3.4701 Å and 60.1°, respectively, assuming the CO 2 and N 2 O are parallel to each other.

Time dependent measurements of nitrous oxide and carbon dioxide collisional relaxation processes by a frequency down-chirped quantum cascade laser: Rapid passage signals and the time dependence of collisional processes

“…27 Such a model has been used to explain the slippedparallel geometry of the dimer formed by N 2 O and CO 2 at low temperatures. [28][29][30] Two recent papers 31,32 have used the interaction potential derived from such dimers to calculate the efficiency of the scattering processes at higher temperatures. Buffa 31 used an ab initio potential of the type pioneered by Green and Hutson 33 for a weakly interacting dimer, whereas Barry et al 32 used a semiempirical potential of the type proposed by Lin et al 34 …”

Infrared spectra of the OCS-CO2 complex: Observation of two distinct slipped near-parallel isomers

“…Similarly, only one form of N 2 O-CO 2 is known experimentally, 26,27 but perhaps there are more, as predicted theoretically. 26,28 In conclusion, we have investigated infrared spectra of the weakly bound OCS-CO 2 complex in the 2060 cm −1 region of the C-O stretching fundamental band of OCS. Two bands were observed and analyzed, corresponding to two distinct isomers of the complex.…”

“…For the isoelectronic system OCS-N 2 O, only one form ͑analogous to isomer a͒ has been reported so far, 25 but maybe there is also an analog to isomer b. Similarly, only one form of N 2 O-CO 2 is known experimentally, 26,27 but perhaps there are more, as predicted theoretically. 26,28 In conclusion, we have investigated infrared spectra of the weakly bound OCS-CO 2 complex in the 2060 cm −1 region of the C-O stretching fundamental band of OCS.…”

Infrared spectra of two isomers of OCS–C2H2 and OCS–C2D2 in the region of OCS ν1 fundamental

“…There are a large number of different complexes made from combinations of relatively simple molecules: for example OCS, N 2 O, CO 2 , and C 2 H 2 which are relevant for the present work. Some complexes have been studied spectroscopically in both the microwave and infrared regions, such as polar (N 2 O) 2 [1][2][3][4], polar (OCS) 2 [5,6], (OCS) 3 [7,8], (C 2 H 2 ) 2 [9,10], OCS-CO 2 [11,12], CO 2 -N 2 O [13][14][15], CO 2 -C 2 H 2 [16,17], and N 2 O-C 2 H 2 [18][19][20][21][22]. Others have been studied only by means of their infrared spectra, either because of their nonpolar structure like nonpolar (N 2 O) 2 [4,[23][24][25][26][27], nonpolar (OCS) 2 [28,29], and (CO 2 ) 2 [30,31], or because of complications arising from extensive hyperfine structure, like (N 2 O) 3 [32,33].…”