Opacity Data for HCN and HNC from a New Ab Initio Line List

Harris, G. J.; Polyansky, Oleg L.; Tennyson, Jonathan

doi:10.1086/342318

Cited by 50 publications

(100 citation statements)

References 23 publications

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“…Figure 2 shows the vibrational angular momentum dependence of the difference between the experimental and ab initio vibrational eigenenergies E vib = T v,(J =0)meas − T v,(J =0)abinitio for the potential surface calculated by Tennyson and co-workers. [83][84][85] The error plot shows a strong vibrational angular momentum dependence. For high l, the ab initio vibrational eigenenergies agree better with the experimental data than for low l. For the HNC eigenenergies the error plot shows a similar dependence 18 but for HNC the error is smaller for the low l states.…”

Section: Rotationally Assigned Ab Initio Eigenenergiesmentioning

confidence: 96%

Complete experimental rovibrational eigenenergies of HCN up to 6880 cm−1 above the ground state

Mellau

2011

The Journal of Chemical Physics

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The [H,C,N] molecular system is a very important model system to many fields of chemical physics and the experimental characterization of highly excited vibrational states of this molecular system is of special interest. This paper reports the experimental characterization of all 3822 eigenenergies up to 6880 cm −1 relative to the ground state in the HCN part of the potential surface using high temperature hot gas emission spectroscopy. The spectroscopic constants for the first 71 vibrational states including highly excited bending vibrations up to v 2 = 10 are reported. The perturbed eigenenergies for all 20 rotational perturbations in the reported eigenenergy range have been determined. The 11 070 eigenenergies up to J = 90 for the first 123 vibrational substates are included as supplement to this paper. We show that a complete ab initio rovibrational analysis for a polyatomic molecule is possible. Using such an analysis we can understand the molecular physics behind the Schrödinger equation for problems for which perturbation theoretical calculations are no more valid. We show that the vibrational structure of the linear HCN molecule persists approximately up to the isomerization barrier and only above the barrier the accommodation of the vibrational states to the double well structure of the potential takes place.

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Section: Rotationally Assigned Ab Initio Eigenenergiesmentioning

confidence: 96%

Complete experimental rovibrational eigenenergies of HCN up to 6880 cm−1 above the ground state

Mellau

2011

The Journal of Chemical Physics

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“…However, additional data in a broader spectral range are necessary to confirm this scenario. We also note that while there is a good line list available for the hot HCN/HNC system (Harris et al 2002;Barber et al 2014), there is no comprehensive line list available for hot C 2 H 2 ; providing such a list is important for future studies of this interesting system. Figure 8.…”

Section: Hcn As a Tracer Of High C/o Ratio Atmospheresmentioning

confidence: 99%

Detection of an Atmosphere Around the Super-Earth 55 Cancri E

Tsiaras

Rocchetto

Waldmann

et al. 2016

ApJ

251

238

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We report the analysis of two new spectroscopic observations in the near-infrared of the super-Earth 55 Cancri e, obtained with the WFC3 camera on board the Hubble Space Telescope. 55 Cancri e orbits so close to its parent star that temperatures much higher than 2000 K are expected on its surface. Given the brightness of 55 Cancri, the observations were obtained in scanning mode, adopting a very long scanning length and a very high scanning speed. We use our specialized pipeline to take into account systematics introduced by these observational parameters when coupled with the geometrical distortions of the instrument. We measure the transit depth per wavelength channel with an average relative uncertainty of 22 ppm per visit and find modulations that depart from a straight line model with a 6σ confidence level. These results suggest that 55 Cancri e is surrounded by an atmosphere, which is probably hydrogen-rich. Our fully Bayesian spectral retrieval code,  -REx, has identified HCN to be the most likely molecular candidate able to explain the features at 1.42 and 1.54 μm. While additional spectroscopic observations in a broader wavelength range in the infrared will be needed to confirm the HCN detection, we discuss here the implications of such a result. Our chemical model, developed with combustion specialists, indicates that relatively high mixing ratios of HCN may be caused by a high C/O ratio. This result suggests this super-Earth is a carbon-rich environment even more exotic than previously thought.

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“…In fact all 45 000 eigenvalues up to the isomerisation barrier have already been calculated. 24,25 molecular system only parity and total angular momentum are exact quantum numbers and the eigenenergies have to be labeled with vibrational quantum numbers in an assignment procedure. This work presents the results from the rotational assignment of all rovibrational eigenenergies up to the isomerisation barrier.…”

Section: Approximate Twofold Rotational Degeneracy Of the Hcn Anmentioning

confidence: 99%

Rovibrational eigenenergy structure of the [H,C,N] molecular system

Mellau¹

2011

The Journal of Chemical Physics

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The vibrational-rotational eigenenergy structure of the [H,N,C] molecular system is one of the key features needed for a quantum mechanical understanding of the HCN HNC model reaction. The rotationless vibrational structure corresponding to the multidimensional double well potential energy surface is well established. The rotational structure of the bending vibrational states up to the isomerisation barrier is still unknown. In this work the structure of the rotational states for low and high vibrational angular momentum is described from the ground state up to the isomerisation barrier using hot gas molecular high resolution spectroscopy and rotationally assigned ab initio rovibronic states. For low vibrational angular momentum the rotational structure of the bending excitations splits in three regions. For J < 40 the structure corresponds to that of a typical linear molecule, for 40 < J < 60 has an approximate double degenerate structure and for J > 60 the splitting of the e and f components begins to decrease and the rotational constant increases. For states with high angular momentum, the rotational structure evolves into a limiting structure for v 2 > 7 -the molecule is locked to the molecular axis. For states with v 2 > 11 the rotational structure already begins to accommodate to the lower rotational constants of the isomerisation states. The vibrational energy begins to accommodate to the levels above the barrier only at high vibrational excitations of v 2 > 22 just above the barrier whereas this work shows that the rotational structure is much more sensitive to the double well structure of the potential energy surface. The rotational structure already experiences the influence of the barrier at much lower energies than the vibrational one.

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Opacity Data for HCN and HNC from a New Ab Initio Line List

Cited by 50 publications

References 23 publications

Complete experimental rovibrational eigenenergies of HCN up to 6880 cm−1 above the ground state

Complete experimental rovibrational eigenenergies of HCN up to 6880 cm−1 above the ground state

Detection of an Atmosphere Around the Super-Earth 55 Cancri E

Rovibrational eigenenergy structure of the [H,C,N] molecular system

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