Combined analysis of the high sensitivity Fourier transform and ICLAS-VeCSEL absorption spectra of D2O between 8800 and 9520 cm

The absorption spectrum of dideuterated water, D₂O, has been recorded between 8800 and 9520 cm⁻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 2v₁ + v₂ + v₃ and the v₂ + 3v₃ bands dominating the spectrum have been determined.     

IUPAC critical evaluation of the rotational-vibrational spectra of water vapor. Part II: Energy levels and transition wavenumbers for HDO, HDO, and HDO

This is the second of a series of articles reporting critically evaluated rotational-vibrational line positions, transition intensities, pressure dependences, and energy levels, with associated critically reviewed assignments and uncertainties, for all the main isotopologues of water. This article presents energy levels and line positions of the following singly deuterated isotopologues of water: HD¹⁶O, HD¹⁷O, and HD¹⁸O. The MARVEL (measured active rotational-vibrational energy levels) procedure is used to determine the levels, the lines, and their self-consistent uncertainties for the spectral regions 0-22 708, 0-1674, and 0-12 105 cm⁻¹ for HD¹⁶O, HD¹⁷O, and HD¹⁸O, respectively. For HD¹⁶O, 54 740 transitions were analyzed from 76 sources, the lines come from spectra recorded both at room temperature and from hot samples. These lines correspond to 36 690 distinct assignments and 8818 energy levels. For HD¹⁷O, only 485 transitions could be analyzed from three sources; the lines correspond to 162 MARVEL energy levels. For HD¹⁸O, 8729 transitions were analyzed from 11 sources and these lines correspond to 1864 energy levels. The energy levels are checked against ones determined from accurate variational nuclear motion computations employing exact kinetic energy operators. This comparison shows that the measured transitions account for about 86% of the anticipated absorbance of HD¹⁶O at 296 K and that the transitions predicted by the MARVEL energy levels account for essentially all the remaining absorbance. The extensive list of MARVEL lines and levels obtained are given in the Supplementary Material of this article, as well as in a distributed information system applied to water, W@DIS, where they can easily be retrieved. In addition, the transition and energy level information for H₂¹⁷O and H₂¹⁸O, given in the first paper of this series [Tennyson, et al. J Quant Spectr Rad Transfer 2009;110:573-96], has been updated.     

Colossal light-induced refractive-index modulation for neutrons in holographic polymer-dispersed liquid crystals

We report strong diffraction of cold neutrons from an only 30 micro m thick holographic polymer-dispersed liquid crystal (H-PDLC) transmission grating. The light-induced refractive-index modulation for neutrons is about 10(-6), i.e., nearly 2 orders of magnitude larger than in the best photo-neutron-refractive materials probed up to now. This makes H-PDLCs a promising candidate for fabricating neutron-optical devices.     

Fourier Transform Spectroscopy of the O(2) Herzberg Bands

From absorption spectra obtained at high resolution by coupling a Fourier transform spectrometer to a long-path multiple reflection cell [A. Jenouvrier, M.-F. Mérienne, B. Coquart, M. Carleer, S. Fally, A. C. Vandaele, C. Hermans, and R. Colin, J. Mol. Spectrosc. 198, 136-162 (1999)] the intensities of the O(2) Herzberg bands (A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), A'( 3)Delta(u)-X(3)Sigma(-)(g)) have been studied at ambient temperature. The integrated cross section values are given for the lines of the (v'-0) bands in the A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), and A'( 3)Delta(u)-X(3)Sigma(-)(g) transitions with v' = 0-11, v' = 2-19, and v' = 2-12, respectively. The band oscillator strengths have been deduced and transition moments have been calculated. The total absorption values in the region of the Herzberg bands together with the photoabsorption values determined previously above the dissociation limit can be modeled by a single curve, in agreement with the continuity relationship of the cross sections through the dissociation limit. Copyright 2000 Academic Press.     

Reconstruction of parasitic holograms to characterize photorefractive materials

Photoinduced light scattering is a serious drawback that limits the applicability of thick holographic recording media but provides valuable information on the recording medium. As long as there is no correlation between the scattering centers in the crystal, photoinduced light scattering may be explained to result from the interference pattern of the incident beam and the field scattered from a single point-like scattering center. The hologram of this ellipsoidally scattered wave field will have practically the same structure in the reciprocal space modified by a response function which reflects the anisotropic properties of the recording medium. We studied photoinduced light scattering in LiNbO₃:Fe, a model system for photorefractive materials. The transmitted intensity in the stationary state of the scattering process is investigated as a function of the reconstruction angle at different wavelengths and polarizations of the reconstructing beam. The experimental results are analyzed by a simple phenomenological model based on the Ewald construction and can be used to choose suitable conditions at which holographic scattering can be minimized as well as to extract some physical parameters of the crystal. Received: 27 September 2000 / Revised version: 1 December 2000 / Published online: 21 February 2001     

An experimental study on the validity of diffraction theories for off-Bragg replay of volume holographic gratings

We perform experiments on the direction of the diffracted beam in off-Bragg replay for volume holographic gratings. The obtained results clearly verify the assumptions made by the first-order two-wave coupling theory for one dimensional lossless unslanted planar volume gratings using the beta-value method rather than Kogelnik??s K-vector closure method.     

High resolution Fourier transform spectroscopy of HD16O: Line positions,absolute intensities and self broadening coefficients in the 8800–11,600 cm−1 spectral region

High-resolution water vapor absorption spectra have been measured at room temperature in the 8800–11,600 cm^?1 spectral region. They were obtained using the mobile BRUKER IFS 120M Fourier transform spectrometer (FTS) from ULB-SCQP coupled to the 50 m base long multiple reflection White type cell in GSMA laboratory. The absorption path was 600 m and different H₂O/HDO/D₂O mixtures were used. Measurements of line positions, intensities and self-broadening coefficients were performed for the HD¹⁶O isotopologue. 6464 rovibrational assignment of the observed lines was made on the basis of global variational predictions and allowed the identification of new energy levels. 3ν₃, 2ν₁+ν₃, 3ν₁+ν₂, ν₁+2ν₃ and 2ν₂+2ν₃ are the five strongest bands. The present paper provides a complementary data set on water vapor for atmospheric and astrophysical applications.     

Fourier transform measurements of SO2 absorption cross sections:: I. Temperature dependence in the 24 000–29 000 cm−1 (345–420 nm) region

Absorption cross sections of SO₂ have been obtained in the 24 000–29 000 cm^?1 spectral range (345–420 nm) with a Fourier transform spectrometer at a resolution of 2 cm^?1. Pure SO₂ samples were used and measurements were performed at room temperature (298 K) as well as at 318, 338 and 358 K. This is the first time that temperature effects in this spectral region are reported and investigated. This paper is the first of a series that will report on measurements of the absorption cross section of SO₂ in the UV/visible region at a higher than previously reported resolution and that will investigate temperature effects in support of tropospheric, stratospheric and astrophysical or planetary applications.     

Fourier transform measurements of SO2 absorption cross sections: II.: Temperature dependence in the 29 000–44 000 cm (227–345 nm) region

This paper is the second of a series that reports results on the measurements of the absorption cross section of SO₂ in the UV/visible region at high resolution and that investigates high temperatures in support to planetary applications. Absorption cross sections of SO₂ have been obtained in the 29 000–44 000 cm⁻¹ spectral range (227–345 nm) with a Fourier transform spectrometer at a resolution of 2 cm⁻¹ (0.4500 cm MOPD and boxcar apodisation). Pure SO₂ samples were used and measurements were performed at room temperature (298 K) as well as at 318, 338 and 358 K. Temperature effects in this spectral region are investigated and are favorably compared to existing studies in the literature. Comparison of the absorption cross section at room temperature shows good agreement in intensity with most of the literature data, but shows that most of the latter suffer from inaccurate wavelength scale definition. Moreover, literature data are often given only on restricted spectral intervals. Combined with the data described in the first part of this series of papers on SO₂, this new data set offers the considerable advantage of covering the large spectral interval extending from 24 000 to 44 000 cm⁻¹ (227–420 nm), at the four temperatures investigated.