Search

Abstract: The high resolution absorption spectrum of dideuterated water, D2O, has been recorded by Intracavity Laser Absorption Spectroscopy (ICLAS) in the 12850–13380cm−1 spectral region which is the higher energy region reported so far for this water isotopologue. Very high deuterium enrichment was necessary to minimize the HDO absorption lines overlapping the D2O spectrum. The achieved sensitivity (noise equivalent absorption α min ∼10−9 cm−1) allowed detecting transitions with line strengths on the order of 5×10−28 cm/molecule. The spectrum analysis, based on recent variational calculations has provided a set of 422 new rovibrational energy levels belonging to 11 vibrational states, including rotational sublevels for four new vibrational states and one level of the (091) highly excited bending state. The very weak (104)–(000) band at 13263.902cm−1, which is the highest D2 16O band currently observed, could be assigned despite the fact that the HDO absorption in the region is stronger by three orders of magnitude. The list of 996 D2 16O transitions is provided as Supplementary Material. [Copyright &y& Elsevier]

Abstract: Assignment of an HDO line list extracted from a recently measured H2O/HDO/D2O Fourier transform absorption spectrum recorded in the 11600–23000cm−1 region by Bach et al. (M. Bach, S. Fally, P.-F. Coheur, M. Carleer, A. Jenouvrier, A.C. Vandaele, J. Mol. Spectrosc. 232 (2005) 341–350.) is presented. More than 94% of the 3256 lines are given quantum number assignments and ascribed to line absorption by HDO; most of the remaining lines are actually due to D2O. High accuracy variational predictions of line positions and intensities are used for the spectral assignment process. Assignments to the ν 1 +5ν 3, 2ν 2 +5ν 3, ν 1 + ν 2 +3ν 3 and ν 1 +6ν 3 bands are presented for the first time. Comparisons are made with published ICLAS spectra covering the same spectral region and suggestions made for its recalibration. The results are used to illustrate the dynamical behaviour of highly excited vibrational states of HDO and to discuss previous vibrational assignments to high lying rotation–vibration states of this system. [Copyright &y& Elsevier]

Abstract: The weak absorption spectrum of dideuterated water, D2O, has been recorded by Intracavity Laser Absorption Spectroscopy (ICLAS) between 11400 and 11900cm−1. This spectrum is dominated by the 3ν 1 + ν 2 + ν 3 and the ν 1 + ν 2 +3ν 3 centered at 11500.25 and 11816.64cm−1, respectively. A total of 530 energy levels belonging to eight vibrational states were determined. The rovibrational assignment process of the 840 lines attributed to D2O was mostly based on the results of new variational calculations consisting in a refinement of the potential energy surface of Shirin et al. [J. Chem. Phys., 120 (2004) 206] on the basis of recent experimental observations, and a dipole moment surface from Schwenke and Partridge [J. Chem. Phys. 113 (2000) 6592]. The overall agreement between these calculations and the observed spectrum is very good both for the line positions and the line intensities. [Copyright &y& Elsevier]

Abstract: Very weak water vapor absorption lines have been investigated by intracavity laser absorption spectroscopy (ICLAS) in the 11335–11947 and 12336–12843cm−1 spectral regions dominated by the ν 1 +3ν 2 + ν 3 and ν 2 +3ν 3 bands, respectively. A detectivity on the order of α min ∼10−9 cm−1 was achieved with an ICLAS spectrometer based on a Ti: Sapphire laser. It allowed detecting transitions with an intensity down to 5×10−28 cm/molecule which is about 10 times lower than the weakest line intensities previously detected in the considered region. A line list corresponding to 1281 transitions with intensity lower than 5×10−26 cm/molecule has been generated. A detailed comparison with the line lists provided by the HITRAN database and by recent investigations by Fourier transform spectroscopy associated with very long multi pass cell is presented. The rovibrational assignment performed on the basis of the ab initio calculations of Schwenke and Partridge, has allowed for determining 176 new energy levels belonging to a total of 16 vibrational states. [Copyright &y& Elsevier]

Abstract: The absorption spectrum of dideuterated water, D2O, has been recorded between 8800 and 9520cm−1 by intracavity laser absorption spectroscopy (ICLAS) based on a vertical external cavity system emitting laser (VeCSEL) and by high sensitivity Fourier Transform spectroscopy. The combined analysis of the spectra has allowed attributing 1223 transitions to the D2O species. The spectrum assignment was performed on the basis of the recent results of variational calculations based on an optimized potential energy surface of D2O. A set of 687 energy levels was derived from transitions assigned to eight upper vibrational states, 577 of them being reported for the first time. A detailed line list has been generated. The line intensities were retrieved mainly from the FTS spectrum and the absolute integrated intensities of the 2v 1 + v 2 + v 3 and the v 2 +3v 3 bands dominating the spectrum have been determined. [Copyright &y& Elsevier]

The HDO absorption FT spectrum is recorded and analyzed in the 7500–8200 cm-1 spectral region. The high accuracy ab initio calculation of Schwenke and Partridge was successfully applied for spectrum assignment that resulted in derivation of 508 precise rovibrational energy levels for the (3 0 0), (0 3 1), (1 1 1), (0 6 0), (2 2 0), and (0 0 2) states, with 295 of them being reported for the first time. In particular, eight new energy levels, including the band center at 7914.3170 cm-1, were derived for the highly excited bending (0 6 0) state from transitions borrowing their intensities through local high-order resonance coupling with the (3 0 0) and (0 3 1) states. [Copyright &y& Elsevier]

Abstract: The high resolution absorption spectrum of dideuterated water, D2 16O, has been recorded by Intracavity Laser Absorption Spectroscopy (ICLAS) in the 13600–14020cm−1 spectral region which is the highest energy region reported so far for this water isotopologue. Because the HD16O absorption is stronger by three orders of magnitude in the region under study, it was necessary to use high deuterium enrichment in order to minimize the HD16O absorption lines overlapping the D2 16O spectrum. With the high sensitivity achieved (noise equivalent absorption αmin ∼10−9 cm−1), transitions with line strengths on the order of 5×10−28 cm molecule−1 could be detected. The spectrum analysis, based on recent variational calculations has provided a set of 177 new rovibrational energy levels belonging to six vibrational states. The most complete set of 53 vibrational energy levels of D2 16O, including the three newly determined band origins, was constructed from an exhaustive review of the literature data. The fitting of the parameters of the vibrational effective Hamiltonian has allowed to reproduce the whole set of vibrational energies with an rms deviation of 0.055cm−1. This simple model gave consistent vibrational labels of the D2 16O states up to 18000cm−1. Above 15000cm−1, Fermi and Darling-Dennison resonance interaction were found to induce strong vibrational mixings of the wave functions in the normal mode basis, leading to ambiguous vibrational labeling. [Copyright &y& Elsevier]

Abstract: The weak absorption spectrum of dideuterated water, D2O, has been recorded between 12450 and 12850cm−1 by high sensitivity Intracavity Laser Absorption Spectroscopy (ICLAS). This spectral region corresponds to the (ν 1 + ν 2/2+ ν 3)=5polyad, dominated by the 4ν 1 + ν 3 band centered at 12743.035cm−1. The achieved sensitivity has allowed for the detection of lines with a minimum intensity of 2×10−28 cm/molecule i.e. typically two orders of magnitude lower than previous observations in the region considered. A total of 586 energy levels belonging to 11 vibrational states were determined. The rovibrational assignment process of 1025 lines ascribed to D2O was based on new results of variational calculations by Shirin et al. [S.V. Shirin, N.F. Zobov, O.L. Polyansky, J. Quant. Spectrosc. Radiat. Transfer, in press, doi:10.1016/j.jqsrt.2007.07.010]. The overall agreement between these calculations and the observed spectrum is good both for the line positions and line intensities. The difficulties encountered while performing the rovibrational labeling and the assignment of the weakest transitions not included in Combination Differences relations, are discussed. [Copyright &y& Elsevier]