To provide precise information relevant to Martian atmospheric remote sensing, high resolution high signal-to-noise ratio spectra of HDO in mixture with CO₂ were recorded in the ν₁, ν₂, and ν₃ fundamental bands between 2.7 and 7 μm regions. The spectra were obtained with the Bruker IFS-125HR Fourier transform spectrometer at the Jet Propulsion Laboratory along with two specially built coolable absorption cells with path lengths of 0.2038 mK. Sung, A.W. Mantz, M.A.H. Smith, L.R. Brown, T.J. Crawford, V.M. Devi, D.C. Benner. J. Mol. Spectrosc. 162 (2010) 124-134.nd 20.941 mA.W. Mantz, K. Sung, T.J. Crawford, L.R. Brown, M.A.H. Smith, V.M. Devi, D.C. Benner, J. Mol. Spectrosc. 304 (2014) 12-24.t various sample gas temperatures ( ∼ 220 – 296 K), total sample pressures and volume mixing ratios. A multispectrum nonlinear least squares techniqueD.C. Benner, C.P. Rinsland, V. Malathy Devi, M.A. H. Smith, and D. Atkins. JQSRT 53 (1995) 705-721.as applied to fit simultaneously all the spectra obtained. The measured line parameters include accurate line positions, intensities, self- and CO₂-broadened Lorentz halfwidth and pressure-shift coefficients, and temperature dependences of CO₂ broadened HDO halfwidth and pressure-shift coefficients. Line mixing coefficients using the relaxation matrix formalism and quadratic speed dependence parameters were also measured where appropriate. Example results for select transitions in each band will be presented and comparisons made to other measured/calculated valuesResearch described in this paper are performed at the College of William and Mary, Jet Propulsion Laboratory, California Institute of Technology, Connecticut College, and NASA Langley Research Center under contracts and cooperative agreements with the National Aeronautics and Space Administration. RRG and CLR were supported by the National Science Foundation through Grant # AGS-1156862.

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Footnotes:

K. Sung, A.W. Mantz, M.A.H. Smith, L.R. Brown, T.J. Crawford, V.M. Devi, D.C. Benner. J. Mol. Spectrosc. 162 (2010) 124-134.a A.W. Mantz, K. Sung, T.J. Crawford, L.R. Brown, M.A.H. Smith, V.M. Devi, D.C. Benner, J. Mol. Spectrosc. 304 (2014) 12-24.a D.C. Benner, C.P. Rinsland, V. Malathy Devi, M.A. H. Smith, and D. Atkins. JQSRT 53 (1995) 705-721.w Research described in this paper are performed at the College of William and Mary, Jet Propulsion Laboratory, California Institute of Technology, Connecticut College, and NASA Langley Research Center under contracts and cooperative agreements with the National Aeronautics and Space Administration. RRG and CLR were supported by the National Science Foundation through Grant # AGS-1156862..

We will present the first experimental measurements of spectral line shapes (self- and air-broadened half width, pressure shift, and line mixing (via off-diagonal relaxation matrix element) coefficients and their temperature dependences, where appropriate, for transitions in the 2ν₃ Q branch manifolds of ¹²CH₄ in the 1.6 μm region. Employing a multispectrum nonlinear least squares techniqueD.C. Benner, C.P. Rinsland, V. Malathy Devi, M.A. H. Smith, and D. Atkins. JQSRT 53 (1995) 705-721 we simultaneously fitted 23 high-resolution spectra of ¹²CH₄ and mixtures of ¹²CH₄ in air, recorded at different pressure-temperature combinations between 130 and 296 K. These data were recorded using the Bruker IFS 125 HR Fourier transform spectrometer at the Jet Propulsion Laboratory together with two coolable sample cellsK. Sung, A.W. Mantz, M.A.H. Smith, L.R. Brown, T.J. Crawford, V.M. Devi, D.C. Benner. J.Mol. Spectrosc. 162 (2010)124-134.^,A.W. Mantz, K. Sung, T.J. Crawford, L.R. Brown, M.A.H. Smith, V.M. Devi, D.C. Benner, J. Mol. Spectrosc. 304 (2014) 12−24. By applying a set of constraints to the parameters of severely blended transitions, a self−consistent set of broadening, shift and line mixing parameters for CH_4−CH_4 and CH_4−air collisions were retrieved. A quadratic speed dependence parameter common for all transitions in each Q(J) manifold was determined. In addition to line shape parameters, line positions and line intensities were also measured for over 100 transitions in the whole Q branch region (5996.5 − 6007.7 cm^-1 A.W. Mantz, K. Sung, T.J. Crawford, L.R. Brown, M.A.H. Smith, V.M. Devi, D.C. Benner, J. Mol. Spectrosc. 304 (2014) 12-24..Research described in this paper are performed at the College of William and Mary, Jet Propulsion Laboratory, California Institute of Technology, Connecticut College, and NASA Langley Research Center under contracts and cooperative agreements with the National Aeronautics and Space Administration.

The 3 μm region of ethane, propane and propene contains a number of vibrational modes dominated by various C-H stretches. Transmission spectra for these hydrocarbons have been obtained at high resolution (0.005 cm⁻¹) and at elevated temperatures (up to 773 K). The integrated absorption cross sections over the isolated 3 μm region are calibrated to those from the Pacific Northwest National Laboratory (PNNL) in order to obtain an effective pressure for the sample. With the Jovian Infrared Auroral Mapper (JIRAM on Juno) due to arrive at Jupiter in July 2016, these cross sections will find use in the study of hot emission from hydrocarbons in the auroral regions of Jupiter. They are also appropriate for modeling atmospheres of hot Jupiter exoplanets and brown dwarfs.

Transmission spectra for hot ammonia (23-700 ^°C) have been recorded in the region 5500-8800 cm⁻¹ and line lists have been produced from these spectra that include line positions, intensities and empirical lower state energies. Transmission spectra were obtained at high resolution (0.02 cm⁻¹) by recording absorption, emission and background spectra using a Bruker IFS 125HR with a hot quartz cell heated by a tube furnace. Temperature-appropriate line lists for the 2500-5500 cm⁻¹ region have been completed and assignment of both regions is undwer way. These empirical line lists will be compared to the theoretical line lists for ammonia available from the ExoMol project and can be used in efforts to model the atmospheres of exoplanets and brown dwarfs.

Continuing a series of studies to investigate the change in structure of hydrocarbons as the amount of fluorination is increased to varying degrees of substitution, we present a survey on the change in the helical nature of the fluorinated carbon backbone when a group is substituted for a terminal group. Spectra for 1H,1H-heptafluorobutan-1-ol, 1H,1H-nonafluoropentan-1-ol, and 1H,1H-undecafluorohexan-1-ol were collected separately using a chirped-pulse FTMW spectrometer in the range of 7-13 GHz. Only one conformation was observed for each molecule. Additional measurements of the 1H,1H-heptafluorobutan-1-ol were completed using a Balle-Flygare cavity instrument. Assignments of the singly-substituted isotopologues of the 1H,1H-heptafluorobutan-1-ol were also measured. A comparison of both ab initio and experimental structures will be presented.

A new spectroscopic scheme has been developed to probe the predissociated levels of the S₁ state of acetylene. Our new scheme is based on detection of visible fluorescence that is a result of multi-photon excitation of acetylene (resonantly through single rovibronic S₁ levels). The new detection scheme is not subject to decreases in fluorescence quantum yield of S₁ levels that lie above the predissociation limit, and laser scatter-light can be easily eliminated by a long-pass filter with a cutoff in the visible range. For the S₁ predissociated levels, the new detection scheme offers much improved signal-to-noise ratio compared to the conventional laser-induced fluorescence technique, based on detection of UV fluorescence from the S₁ levels. The new method is also easier to implement than various H-atom detection schemes, which involve one additional laser of different wavelength than the excitation wavelength. Based on the power dependence and lifetime of the fluorescence signals, electronically excited C₂H and/or C₂ fragments are the likely emitters of the detected visible fluorescence. The new method is currently being used to extend the vibrational and rotational assignments of both gerade and ungerade levels of the S₁ state of acetylene in the region of the cis-trans isomerization barrier, > 1000 cm⁻¹ above the onset of S₁ predissociation.

Pure rotational spectra of Sc¹³C₂ and Sc¹²C¹³C (~X²A₁) have been obtained using Fourier Transform Microwave methods. These molecules were created from scandium vapor in combination with ¹³CH₄ and/or ¹²CH₄, diluted in argon, using a Discharge Assisted Laser Ablation Source (DALAS). Transitions in the frequency range of 14-30 GHz were observed for both species including hyperfine splitting due to the nuclear spin of Sc (I = 7/2) and ¹³C (I = 1/2). Rotational, spin-rotational, and hyperfine constants have been determined for Sc¹³C₂ and Sc¹²C¹³C, as well as a refined structure for ScC₂. In agreement with theoretical calculations and previous Sc¹²C₂ results, these data confirm a cyclic (or T-shaped) structure for this molecule. Scandium carbides have been shown to form endohedral-doped fullerenes, which have unique electrical and magnetic properties due to electron transfer between the metal and the carbon-cage. Spectroscopy of ScC₂ provides data on model systems for comparison with theory.

In this work, we report the fluorescence emission spectra of NO molecules excited using a low power glow discharge under different experimental conditions such as different gas pressure, buffer gases, NO concentration, discharge voltage and time evolution of Ar/NO density ratio as well. This glow discharge electronic excitation populated different high lying energy states like quartet and doublet states of NO in its proximity such as the A ²Σ (ν = 2), b ⁴Σ - (ν = 3), B ²II (ν = 4) and X ²II (ν = 33 - 32) states. Due to intersystem crossing, emission lines originating from these levels to lower lying states were recorded and spectral line assignments were performed. Observed systems included b b ⁴Σ- a ⁴II , B ²II - a ⁴II , a ⁴II - X ²II, A ²II -X ²II and X ²II -X ²II. This investigation could assist in understanding the interesting features of NO molecule such as collision processes, population dynamics and energy transfer within molecules.

The spectra of some astrophysical sources contain signatures from molecules containing magnesium or sulphur atoms. Therefore, we have extended previous studies of the diatomic molecule MgS, which is a possible candidate for astrophysical detection. Microwave spectra of X¹Σ⁺ , the ground electronic state, were reported in 1989S. Takano, S. Yamamoto and S. Saito, Chem. Phys. Lett. 159, 563-566 (1989).nd 1997K. A. Walker and M. C. L. Gerry, J. Mol. Spectrosc 182, 178-183 (1997). and the B¹Σ⁺-X¹Σ⁺ electronic absorption spectrum in the blue was last studied in 1970M. Marcano and R. F. Barrow, Trans. Faraday Soc. 66, 2936-2938 (1970). We have investigated the B¹Σ⁺-X¹Σ⁺ 0-0 spectrum of MgS at high resolution under jet-cooled conditions in a laser-ablation molecular source, and have obtained laser-induced fluorescence spectra from four isotopologues. Dispersed fluorescence from this source identified the low-lying A¹Π state near 4520 cm⁻¹. We also created MgS in a Broida oven, with the help of a stream of activated nitrogen, and took rotationally resolved dispersed fluorescence spectra of the B¹Σ⁺-A¹Π transition with a grating spectrometer by laser excitation of individual rotational levels of the B¹Σ⁺ state via the B¹Σ⁺-X¹Σ⁺ transition. These spectra provide a first observation and analysis of the A¹Π state.

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Footnotes:

S. Takano, S. Yamamoto and S. Saito, Chem. Phys. Lett. 159, 563-566 (1989).a K. A. Walker and M. C. L. Gerry, J. Mol. Spectrosc 182, 178-183 (1997)., M. Marcano and R. F. Barrow, Trans. Faraday Soc. 66, 2936-2938 (1970)..

The near-infrared spectrum of NiCl has been recorded in high resolution in the 13,200-13,500 cm⁻¹and 13,600-13,750 cm⁻¹regions using Intracavity Laser Spectroscopy (ILS). The NiCl Molecules were produced in the plasma discharge of a Ni-lined copper hollow cathode with 0.3-0.6 torr of argon as the sputter gas, and a trace amount of CCl₄. The hollow cathode was located within the laser cavity of a Verdi V-10 pumped Ti:sapphire system. A generation of 90 μsec resulted in an effective pathlength of approximately 700 m for the absorption measurements. Several transitions were observed, including 3 transitions involving 2 previously unreported electronic states. The (0,0) and (1,0) bands of the [13.5] ²Φ_7/2-[0.16] A ²∆_5/2 transition were observed near 13,709 cm⁻¹and 13,318 cm⁻¹, respectively. The (0,0) band of the [13.8] ²Π_1/2 - [0.38] X ²Π_1/2 transition was observed near 13,480 cm⁻¹. With the analysis of these transitions, molecular constants have been obtained for 9 of the 12 doublet states of NiCl predicted by Zou and Lou in 2006. Analysis of these transitions and a comparison between the experimentally observed transitions and the theoretically predicted states of NiCl will be presented.

The many decades of work on determining accurate analytic pair potentials for rare gas dimers from experimental data focussed largely on the use of bulk non-ideal gas and collisional properties, with the use of spectroscopic data being somewhat of an afterthought, for testing the resulting functions. This was a natural result of experimental challenges, as the very weak binding of ground-state rare gas pairs made high resolution spectroscopy a relatively late arrival as a practical tool in this area. However, we believe that it is now time for a comprehensive reassessment. Following up on a preliminary report at this meeting five years ago,R.J. Le Roy, C.J.W. Mackie, P. Chandrasekhar and K.M.\ Sentjens, "Accurate New Potential Energy Functions From Spectroscopic and Virial Coefficient Data for the Ten Rare Gas Pairs formed from Ne, Ar, Kr and Xe, paper MF03 at the 66^th Ohio State University International Symposium on Molecular Spectroscopy, Columbus, Ohio, June 13-17 (2011).his paper describes work to determine a new generation of empirical potential energy functions for the four heavier (i.e., not involving He) homonuclear rare gas pairs from direct fits to all available spectroscopic, pressure virial, and acoustic virial coefficient data, with the resulting functions being `tuned' by comparisons with available thermal transport property data: viscosity, mass diffusion and thermal diffusion, and thermal conductivity data, and tested against the best available ab initio potentials. The resulting functions are everywhere smooth and differentiable to all orders, incorporate the correct (damped) theoretical inverse-power long-range behaviour, and have sensible short-range extrapolation behaviour.

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Footnotes:

R.J. Le Roy, C.J.W. Mackie, P. Chandrasekhar and K.M.\ Sentjens, "Accurate New Potential Energy Functions From Spectroscopic and Virial Coefficient Data for the Ten Rare Gas Pairs formed from Ne, Ar, Kr and Xe, paper MF03 at the 66^th Ohio State University International Symposium on Molecular Spectroscopy, Columbus, Ohio, June 13-17 (2011).t

We present helium- and hydrogen-broadened linewidths, pressure-induced shifts, and collisional narrowing coefficients for selected lines in the P- and R- branch of the second overtone (3–0) band of CO, spanning from 6270 cm⁻¹to 6402 cm⁻¹. The contribution of speed dependent effects and partial correlation between velocity-changing and dephasing collisions on the foreign broadened line shapes are also discussed. The data were obtained using the frequency-stabilized cavity ringdown spectroscopy technique. Spectra were collected at room temperature over a pressure range from 13.3 kPa to 100 kPa. The spectrum frequency axis is referenced via an optical frequency comb to a Cs clock, which provides pressure shifting values with uncertainties as low as 100 kHz/atm. The spectra exhibited signal-to-noise ratios as high as 20,000:1, which enables rigorous tests of theoretical line profiles through multi-spectrum least squares data analysis. The partially correlated, quadratic-speed-dependent Nelkin Ghatak profile gives a quality of fit mostly commensurate with the high spectrum signal-to-noise and minimizes structural residuals.

We present the results of ab initio calculations for the lower electronic states of the Group 15 (pnictogen) dihydrides, SbH₂ and BiH₂. For each of these molecules the two lowest electronic states become degenerate at linearity and are therefore subject to the Renner effect. Spin-orbit coupling is also strong in these two heavy-element containing molecules. For the lowest two electronic states of SbH₂, we construct the three dimensional potential energy surfaces and corresponding dipole moment and transition moment surfaces by multi-reference configuration interaction techniques. Including both the Renner effect and spin-orbit coupling, we calculate term values and simulate the rovibrational and rovibronic spectra of SbH₂. Excellent agreement is obtained with the results of matrix isolation infrared spectroscopic studies and with gas phase electronic spectroscopic studies in absorption [1,2]. For the heavier dihydride BiH₂ we calculate bending potential curves and the spin-orbit coupling constant for comparison. For SbH₂ we further study the local mode vibrational behavior and the formation of rovibronic energy level clusters in high angular momentum states.   [1] X. Wang, P. F. Souter and L. Andrews, J. Phys. Chem. A 107, 4244-4249 (2003) [2] N. Basco and K. K. Lee, Spectroscopy Letters 1, 13-15 (1968)

The bichromatic force is a coherent optical force that has been demonstrated to exceed the saturated radiative force from a monochromatic cw laser by orders of magnitude in atomic systems. By stimulating photon emission between two states, the bichromatic force allows us to increase the photon scattering rate beyond the spontaneous emission rate while also suppressing decays into dark states. We present studies of the efficacy of the bichromatic force on molecular systems using the test cases of B-X (0,0), P₁₁(1.5)/^PQ₁₂(0.5) in CaF and Ã(000)−X̃(000), P₁₁(1.5)/^PQ₁₂(0.5) in the linear triatomic molecule SrOH. Computational results from detailed multilevel models indicate that both of these molecular systems are suitable for the use of the bichromatic force, with neither repumping nor magnetic destabilization of dark states interrupting the coherent cycling at the heart of the force. We comment on the applicability of the bichromatic force to arbitrary polyatomic molecules, and present our experimental progress in demonstrating the bichromatic force on CaF and possibly on SrOH.Supported by the National Science Foundation.html:<hr /><h3>Footnotes: Supported by the National Science Foundation.