Pulsed molecular beam infrared absorption spectroscopy of CO2 dimer

High-resolution infrared spectroscopy of carbon dioxide dimers, trimers, and larger clusters

“…Although the coverage is fairly good, it is of course still restricted by the tuning ranges of our available diode laser sources and the limited supply of isotopically substituted gas. The spectrum of the normal isotope of (CO 2 ) 2 in the 3 fundamental band region has already been well studied in the pioneering work of Walsh et al [5]. Here we report our own analysis of this spectrum, not so much because of improvements (which are slight), but rather for consistency with the 13 C results described below.…”

“…[5] the main improvement here is a narrower line width ($0.0017 vs. 0.004 cm À1 ) resulting from a jet source with a slit (rather than pinhole) nozzle. This is illustrated in the top panel of Figure 1, which covers the same region as shown in Ref.…”

“…In 1984, Miller and Watts [1] observed sharp lines corresponding to the resolved (CO 2 ) 2 rotational structure in the 3700 cm À1 region of the 1 þ 3 /2 2 þ 3 combination bands of CO 2 . Three years later, the analysis of this [2][3][4] and a corresponding spectrum [5] in the 3 fundamental band region ($2350 cm À1 ) showed that the dimer has a planar slipped-parallel structure with centrosymmetric C 2h symmetry. Around the same time, an interesting symmetric-top spectrum of the CO 2 trimer in the 3700 cm À1 region was studied by Fraser et al [6], who derived a planar cyclic structure with C 3h symmetry.…”

High resolution infrared spectroscopy of carbon dioxide clusters up to (CO2)13

“…This is illustrated in Fig. 7, which includes the known CO 2 monomer, dimer, 5 Q-branch feature at 2352.60 cm −1 (labeled "Q A ") (Refs. 7, 8, and 10) might be due to (CO 2 ) 4 and this point is also included in Fig.…”

“…More generally, clusters represent the "missing" link between single molecules or molecular pairs and the bulk liquid or solid phases, and intermolecular forces play a key role in this transition region. Carbon dioxide dimers [1][2][3][4][5] and trimers [6][7][8] were extensively studied by high-resolution infrared spectroscopy in the period from 1984 to 1996. The dimer was shown to have a planar slipped-parallel structure, with centrosymmetric C 2h symmetry.…”