Spectrum of hot water in the 2000-4750 cm frequency range

An emission spectrum recorded in an oxyacetylene torch [P.-F. Coheur, P.F. Bernath, M. Carleer, R. Colin, O.L. Polyansky, N.F. Zobov, S.V. Shirin, R.J. Barber, J. Tennyson, J. Chem. Phys. 122 (2005) 074307] is analyzed for the region covering stretching fundamentals and associated hot bands of water. Many lines could be assigned on the basis of previously determined energy levels. New assignments made with a new variational linelist allow a further 800 energy levels covering 15 vibrational states and rotations up to J = 32 to be assigned. A simultaneous re-analysis of previously reported sunspot absorption spectra leads to the assignment of 581 further lines in the L-band spectrum and 67 in the N-band spectrum.     

Infrared emission spectrum of hot D2O

An emission spectrum of hot D₂O (1500 °C) has been analyzed in the 2077-4323 cm⁻¹ region. A considerable number of new vibration-rotation energy levels have been determined and two new vibrational levels identified. The new (0 4 1) and (0 2 2) vibrational levels have estimated band origins of 7343.93 ± 0.01 and 7826.38 ± 0.02 cm⁻¹, respectively.     

Identification of hot band transitions of CH4 near 3000 cm

Rovibrational transitions between vibrationally excited states of ¹²CH₄ in the 3.4 μm wavelength region are investigated by a pump-probe technique using an optical parametric oscillator as a pump and a tunable diode laser as a probe. Methane molecules are excited into selected levels of the 2ν₃ state of the tetradecad and numerous transitions between pentad and tetradecad, and between tetradecad and triacontad, have been observed in this spectral range. Positions and assignments of transitions involving a level of the 2ν₃ (F₂) substate are reported. Reliable energy values for 2ν₃ (F₂) levels up to J = 6 are obtained, and the energies and assignments of a number of 3ν₃ levels have been deduced allowing identification of IR lines in the 1.1 μm region.     

Observation of hot bands in the infrared spectrum of H2CO

Two hot bands in the infrared spectrum of formaldehyde (H₂CO) have been identified by means of tunable infrared laser spectroscopy using a jet-cooled sample. One band falls in the region 2760-2800 cm⁻¹; it follows a-type selection rules and it has been assigned as the ν₁ + ν₄ − ν₄ hot band. The other band falls in the region 2800-2860 cm⁻¹; it follows b-type selection rules and it has been assigned as the ν₅ + ν₄ − ν₄ hot band. The observations are restricted to low J and K_a levels. It has consequently been possible to ignore the effects of the extensive Coriolis couplings involving these levels in the analysis of the spectra and to model the rotational structure as that of a simple asymmetric top. Least-squares fits of the data have provided values for the band origins: 2774.2706(11) cm⁻¹ for the ν₁ + ν₄ − ν₄ and 2829.2621(8) cm⁻¹ for the ν₅ + ν₄ − ν₄ band. Term values for the upper vibrational levels involved in the transitions have been determined by use of the previously reported term values for the v₄ = 1 level.     

The hot bands of silane between 2120 and 2270 cm

The infrared spectrum of the SiH₄ molecule has been recorded between 2040 and 2320 cm⁻¹ using the high-resolution Fourier interferometer of the Laboratoire de Photophysique Moléculaire (Orsay, France). The resolution was 5.4 × 10⁻³ cm⁻¹. In this region, many lines were previously analyzed and assigned to the ν₁/ν₃ stretching dyad of ²⁸SiH₄, ²⁹SiH₄, and ³⁰SiH₄ molecules [J. Mol. Spectrosc. 143 (1990) 35]. However, several lines in the spectrum were not assigned. The results obtained in our previous study [J. Mol. Spectrosc. 197 (1999) 307] of the infrared spectrum of ²⁸SiH₄, in the bending-stretching tetrad region at 3100 cm⁻¹, enabled us to assign 204 of the observed transitions to hot bands (the ν₁ + ν₂/ν₁ + ν₄/ν₂ + ν₃/ν₃ + ν₄ bending-stretching tetrad minus the ν₂/ν₄ bending dyad). These transitions were used to refine the set of the Hamiltonian parameters of the bending-stretching tetrad. The analysis is performed using the tensorial formalism developed in Dijon for tetrahedral molecules and implemented in the STDS software (http://www.u-bourgogne.fr/LPUB/shTDS.html).     

HDO absorption spectrum above 11 500 cm: Assignment and dynamics

Assignment of an HDO line list extracted from a recently measured H₂O/HDO/D₂O Fourier transform absorption spectrum recorded in the 11 600-23 000 cm⁻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 ν₁ + 5ν₃, 2ν₂ + 5ν₃, ν₁ + ν₂ + 3ν₃ and ν₁ + 6ν₃ 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.     

Water vapour line assignments in the 9250-26 000 cm frequency range

Line parameters for water vapour in natural abundance have recently been determined for the 9250-13 000 cm⁻¹ region [M.-F. Mérienne, A. Jenouvrier, C. Hermans, A.C. Vandaele, M. Carleer, C. Clerbaux, P.-F. Coheur, R. Colin, S. Fally, M. Bach, J. Quant. Spectrosc. Radiat. Transfer 82 (2003) 99] and the 13 000-26 000 cm⁻¹ region [P.-F. Coheur, S. Fally, M. Carleer, C. Clerbaux, R. Colin, A. Jenouvrier, M.-F. Mérienne, C. Hermans, A.C. Vandaele, J. Quant. Spectrosc. Radiat. Transfer 74 (2002) 493] using a high-resolution Fourier-transform spectrometer with a long-path absorption cell. These spectra are analysed using several techniques including variational line lists and assignments made. In total, over 15 000 lines were assigned to transitions involving more than 150 exited vibrational states of H₂¹⁶O. Twelve new vibrational band origins are determined and estimates for a further 16 are presented.     

Water line parameters for weak lines in the range 7400-9600 cm

A long pathlength, Fourier transform spectrum of pure water vapour [J. Mol. Spectrosc. 211 (2002) 169] has been fitted and analysed. Line centres, intensities, and self-broadening parameters have been obtained for about 3900 lines with intensities less then 1 × 10⁻²⁴ cm/molecule. Transitions to 240 newly observed energy levels of H₂O have been identified. 855 lines have been assigned to three other major isotopologues of water. It is pointed out that a new intensity measurements are needed for the stronger lines in this region.     

The high-resolution infrared spectrum of isoxazole vapor between 800 and 1700 cm

The Fourier transform gas-phase IR spectrum of isoxazole, C₃H₃NO, between 550 and 1700 cm⁻¹ was measured with a resolution of ca. 0.003 cm⁻¹. Ten fundamental bands in the region 800-1700 cm⁻¹ have been analyzed by the Watson Hamiltonian model to yield upper state spectroscopic constants. A number of local resonances have been identified in the bands and explained qualitatively, and the unobserved ν₁₄(A″) fundamental band has been located at 897.5(5) cm⁻¹ from its perturbation effects on the neighboring fundamentals.     

High-resolution synchrotron far-infrared spectroscopy of acrolein: The vibrational levels below 700 cm

The far-infrared spectrum of acrolein, CH₂CHCHO, is studied in the 100–360 cm⁻¹ region using continuum radiation from a synchrotron source. The combination of a very high resolution spectrometer, a long absorption path, and a low sample pressure, yields observed line widths of less than 0.0008 cm⁻¹. Observation of the ν₁₈ (157.9 cm⁻¹), and ν₁₃ (323.8 cm⁻¹) fundamental bands, together with six hot bands in the same regions, gives information on eight low-lying vibrational states of the molecule, including the Fermi and Coriolis interactions among them. Combining the present assignments with previous data on the ν₁₂ (564.34 cm⁻¹) and ν₁₇ (593.08 cm⁻¹) fundamental bands, all ten excited vibrational levels below 700 cm⁻¹ are analyzed in terms of one 1-state fit, two 2-state fits, and one 5-state fit.     

Water line parameters for weak lines in the range 9000-12 700 cm

A total of 7923 transitions previously derived from long pathlength, Fourier transform spectra of pure water vapor (Schermaul et al., J. Mol. Spectrosc. 211 (2002) 169) have been refitted and reanalyzed using a newly calculated variational linelist. Of these, 6600 lines are weaker than 1 × 10⁻²⁴ cm/molecule, for which reliable intensities are obtained. These weak lines include 1082 lines, largely due to H₂¹⁶O, which have not been previously observed. A total of 7156 lines were assigned resulting in 329 new energy levels for H₂¹⁶O spread over 32 vibrational levels. Estimates are also given for the band origins of the (022), (140), and (051) vibrational states.     

Emission spectrum of MgCl molecule in 5030-4380Å

The emission spectrum of diatomic magnesium chloride molecule has been reinvestigated in the region 5030-4380 Å (B ²Σ⁺ —A ²Π transition) at a higher dispersion. The vibrational assignments of the bands are confirmed by observing the vibrational isotope shifts due to isotopes of magnesium and chlorine. Precise values of the vibrational constants are determined for theB ²Σ⁺ state.     

High resolution Fourier transform spectrum of HDO in the 7500-8200 cm region: revisited

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.     

空气电晕放电中的OH自由基发射光谱

测量了大气压下向空气中喷射不饱和水蒸气的电晕放电产生的OH自由基的发射光谱。通过对光谱线强度变化的分析,研究了电场强度、放电方式、水蒸气比例等因素对OH自由基产生过程的影响,及OH自由基浓度在放电反应空间的分布特点。     

Preliminary analysis of CH3D from 3250 to 3700 cm

The infrared spectrum of CH₃D from 3250 to 3700 cm⁻¹ was studied for the first time to assign transitions involving the ν₂ + ν₃, ν₂ + ν₅, ν₂ + ν₆, ν₃ + 2ν₆ and 3ν₆ vibrational states. Line positions and intensities were measured at 0.011 cm⁻¹ resolution using Fourier transform spectra recorded at Kitt Peak with isotopically enriched samples. Some 2852 line positions (involving over 900 upper state levels) and 874 line intensities were reproduced with RMS values of 0.0009 cm⁻¹ and 4.6%, respectively. The strongest bands were found to be ν₂ + ν₃ at 3499.7 cm⁻¹ and ν₂ + ν₆ at 3342.5 cm⁻¹ with integrated strengths, respectively, of 8.17 × 10⁻²⁰ and 2.44 × 10⁻²⁰ (cm⁻¹/molecule · cm⁻²) at 296 K (for 100% CH₃D). The effective Hamiltonian was expressed in terms of irreducible tensor operators and adapted to symmetric top molecules. Its present configuration in the MIRS package permitted simultaneous consideration of the four lowest polyads of CH₃D: the Ground State (G.S.), the Triad from 6.3 to 9.5 μm, the Nonad from 3.1 to 4.8 μm and now the Enneadecad (19 bands) from 2.2 to 3.1 μm. The CH₃D line parameters for this interval were calculated to create a new database for the 3 μm region.     

飞秒激光与等离子体相互作用过程中超热电子能谱的测量

 报道了在3TW飞秒激光器上完成的激光 等离子体相互作用过程中产生的超热电子的能谱测量结果。能谱测量显示：在较低的能段，超热电子能谱先是呈现一个局部的平台，然后迅速衰减，呈现非类麦克斯韦分布，这是由于几种加热机制共同作用，其中占主导地位的是反射激光对电子的加速；在较高的能段，超热电子能谱呈类麦克斯韦分布，拟合的温度远远高于已知的温度定标律给出的温度，其原因在于超热电子分布的高能尾部本身的抬高和激光的自聚焦及成道。     

含Kerr介质的Fock态和相干态腔场中耦合双原子辐射谱

研究了在充满Kerr介质的高Q腔中两个具有偶极-偶极相互作用的二能级原子辐射谱,给出了初始光场为Fock态和相干态时辐射谱的数值结果.讨论了Kerr效应对谱结构的影响.在初始注入光场为较强的相干态时,辐射谱除中心单峰外,两侧各出现一个多峰梳状边带,峰的个数随初始场平均光子数-n的增大而增多,峰间距随Kerr介质与光场的耦合系数X的增大而增大,两个边带则随Xn-的增大逐渐远离.     

ICLAS of HDO between 13,020 and 14,115 cm

The high resolution absorption spectrum of monodeuterated water, HDO, has been recorded by Intracavity Laser Absorption Spectroscopy (ICLAS) in the 13,020–14,115 cm⁻¹ region dominated by the 4ν₃ band. The achieved noise equivalent absorption (α_min10⁻⁹ cm⁻¹) allowed detecting transitions with line strengths as small as 2×10⁻²⁷ cm/molecule which is about 10 times lower than the smallest line intensities previously detected in the region.The rovibrational assignment of the spectrum was based on the results of the variational calculations of Schwenke and Partridge (SP) as well as recent calculations using a new potential energy surface performed by Voronin, Tolchenov and Tennyson (VTT). 2157 transitions involving 21 upper vibrational states were assigned to HD¹⁶O while only four bands were previously reported in the region. A set of 157 new energy levels could be derived. It includes rotational levels of several highly excited bending states, in particular the (0 11 0) pure bending state. For some states like the (1 0 3) and (0 2 3) Fermi dyad, effective Hamiltonian modelling was needed to establish the vibrational assignments of some rotational levels. VTT calculations were found to significantly improve the SP results, the rms deviation of the calculated and observed energies being decreased from 0.23 to 0.06 cm⁻¹.Finally, 79 transitions of the 4ν₃ band of the HD¹⁸O isotopologue were assigned, leading to the derivation of 48 levels, which are the most excited energy levels reported so far for this isotopologue.     

Fourier transform measurements of water vapor line parameters in the 4200-6600 cm region

New high-resolution water vapor absorption spectra were obtained at room temperature in the 4200-6600 cm⁻¹ spectral region by combining Fourier transform spectrometers (FTS) with single and multiple reflection cells. With absorption paths from 0.3 to 1800 m in pure and air diluted water vapor, accurate measurements of about 10400 lines in an intensity range from 10⁻²⁹ to 10⁻¹⁹ cm/molecule have been performed. Positions, intensities, self- and air-broadening coefficients and air-induced shifts were determined for the H₂¹⁶O, H₂¹⁷O, H₂¹⁸O and HDO isotopologues. The rovibrational assignment of the observed lines was performed with the use of global variational predictions and allowed the identification of several new energy levels. One major contribution of this work consists of the identification of 3280 new weak lines. A very close agreement between the new measured parameters and those listed in the database is reported as well as between the observations and the most recent variational calculations for the positions and the intensities. The present parameters provide an extended and homogeneous data set for water vapor, which is shown to significantly improve the databases for atmospheric applications, especially in the transmission windows on both sides of the band centered at 5400 cm⁻¹.     

Emission characteristics of a gas-discharge plasma of water vapor in the vacuum UV region of the spectrum

We present the results of a study of emission from a low-density water vapor plasma in the vacuum ultraviolet (VUV) region of the spectrum. The plasma was formed in a longitudinal glow discharge. We have studied the spectral characteristics of the plasma and also the dependences of the relative energy characteristics of the hydroxyl (OH) emission band on the discharge current and the helium partial pressure in a He-H₂O mixture in the spectral range 130–190 nm. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 831–833, November–December, 2006.