The Water Dimer Investigated in the 2OH Spectral Range Using Cavity Ring-Down Spectroscopy

Abstract

Two setups based on CW cavity ring-down spectroscopy were used at Bruxelles and Rennes to record jet-cooled water dimer absorption between 7188 and 7285, and between 7357 and 7386 cm(-1). Some 19 absorption features are reported, significantly more than in the literature. Limited high-resolution information is available due to strong overlap between neighboring vibration-rotation-tunneling (VRT) structures and to spectral broadening induced by short upper state vibrational predissociation lifetimes, likely to range between 100 and 20 ps. Rotational band contours analyses are performed to assign the partly resolved VRT structures to the v1v2v3,vfvb = 000,11; 200,00; 000,20; and 101,00 zero-order vibrational states. Their wavenumbers are found to be 7192.34, 7225.86, 7240.57, and 7256.99 cm(-1), respectively. Both so-called acceptor-switching tunneling components are involved in the assignments whose tentative character is discussed.

Overtone spectroscopy of molecular complexes containing small polyatomic molecules

“…the so-called acceptor-switching (AS) and interchange tunnelings [40]. Simulation of the band contours using PGOPHER [220] played a crucial role in the tentative sub-band assignment, summarised in Figure 31, after [219]. The sub-band assignment tentatively suggested in Figure 31 significantly modifies and extends ab initio predictions (e.g.…”

“…The (NH 3 ) 2 dimer was looked for also using FANTASIO+, so far unsuccessfully. Larger multimers have been observed for 2CH-excited acetylene [131] (see Table 1 and Figure 7(c)) and, possibly for 2OH-excited water [219], using cw-CRDS. They are not further discussed here.…”

“…Later, additional experiments were undertaken in both CQP/ULB and the Institut de Physique in Rennes to cover a broader wavelength range in the 2OH excitation region [219]. The latter set-up also uses cw-CRDS and the expansion is produced using a very large roots pumping system [265].…”

“…The latter set-up also uses cw-CRDS and the expansion is produced using a very large roots pumping system [265]. All experimental conditions are reported in [219]. A few more rotationally resolved bands were recorded, as well as a large deal of barely resolved band contours.…”

Spectra of the D2O dimer in the O–D fundamental stretch region: Vibrational dependence of tunneling splittings and lifetimes

“…[7][8][9] Recently, there has also been activity concerning O-H stretching overtones in the near infrared region, revealing rich spectra that are not yet fully understood. [10][11][12]…”