Knowledge Bank

High resolution infrared absorption spectra of the weakly bonded Ar-$N2O$ complex have been observed in the $2256cm-1$ region. The observed featured are assigned to a combination band consisting of one quantum of stretch (predominantly $v3$ of $N2O$ and one quantum of intermolecular vibration. The signals are 200 times less intense and $33cm-1$ to the blue of the Ar-$N2O$ ($v3$) stretching $frequency.1$ Prior estimates based on centrifugal distortion constants, derived from microwave $data,2$ Placed the intermolecular bend and stretch at 46 and $39cm-1$, respectively. Only A-type transitions are observed and analysis of the rotational constants gives $A=13202.92(98)$ MHz, $B=1947.83(13)$, $C=1637.88(13)$ and $V0=2256.06500(8)cm-1$. An anomalously large inertial defect of 10.82 annu \AA$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ is indicative of significant rotation-vibration interactions. This second-generation, infrared, diode laser, spectrometer is similar to the one developed by $Sharpe3$ et al. and features an improved 12 cm $\times$ 150 micron pulsed slit nozzle. The spectrometer incorporates a fast scan technique allowing us to optimize the absorption signals on a per-gas-pulse $basis.4$ A high quality spectrum of up to 3 wave numbers in length typically requires 90 seconds to record with a nozzle rate of 3 Hz. A White cell allows us to multi-pass the laser light 32 times through the expending effluent for a total optical path length of 3.8 meters. Preliminary characterization of this instrument indicates sensitivity on the order of $2.5\times 10-5$ absornance (i.e., I part in 40,000) and resolution approaching 20MHz. We believe complexes via the much weaker combination bands.