Double Resonance Sub-Doppler Study of the Allowed and ΔK = −3ForbiddenQ(3, 3)Transitions to the ν2Vibrational State of14NH3

Fichoux, H.; Khelkhal, M.; Rusinek, E.; Legrand, J.; Herlemont, F.; Urban, Štěpán

doi:10.1006/jmsp.1998.7668

Cited by 16 publications

(16 citation statements)

References 33 publications

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“…The operator code for this interaction is 600VV in the SPFIT/ SPCAT programs A total of 4394 transitions were included in the current analysis, including 2166 transitions assigned in this study and 2228 transitions from previous microwave studies 16,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] and infrared studies. [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] Each of the 4394 transitions was weighed by its experimental uncertainty.…”

Section: Resultsmentioning

confidence: 99%

Submillimeter-wave and far-infrared spectroscopy of high-J transitions of the ground and ν2=1 states of ammonia

Pearson

Drouin

et al. 2010

The Journal of Chemical Physics

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Complete and reliable knowledge of the ammonia spectrum is needed to enable the analysis and interpretation of astrophysical and planetary observations. Ammonia has been observed in the interstellar medium up to J=18 and more highly excited transitions are expected to appear in hot exoplanets and brown dwarfs. As a result, there is considerable interest in observing and assigning the high J (rovibrational) spectrum. In this work, numerous spectroscopic techniques were employed to study its high J transitions in the ground and ν2=1 states. Measurements were carried out using a frequency multiplied submillimeter spectrometer at Jet Propulsion Laboratory (JPL), a tunable far-infrared spectrometer at University of Toyama, and a high-resolution Bruker IFS 125 Fourier transform spectrometer (FTS) at Synchrotron SOLEIL. Highly excited ammonia was created with a radiofrequency discharge and a dc discharge, which allowed assignments of transitions with J up to 35. One hundred and seventy seven ground state and ν2=1 inversion transitions were observed with microwave accuracy in the 0.3–4.7 THz region. Of these, 125 were observed for the first time, including 26 ΔK=3 transitions. Over 2000 far-infrared transitions were assigned to the ground state and ν2=1 inversion bands as well as the ν2 fundamental band. Of these, 1912 were assigned using the FTS data for the first time, including 222 ΔK=3 transitions. The accuracy of these measurements has been estimated to be 0.0003–0.0006 cm−1. A reduced root mean square error of 0.9 was obtained for a global fit of the ground and ν2=1 states, which includes the lines assigned in this work and all previously available microwave, terahertz, far-infrared, and mid-infrared data. The new measurements and predictions reported here will support the analyses of astronomical observations by high-resolution spectroscopy telescopes such as Herschel, SOFIA, and ALMA. The comprehensive experimental rovibrational energy levels reported here will permit further refinement of the potential energy surface to improve ammonia ab initio calculations and facilitate assignment of new high-resolution spectra of hot ammonia.

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Section: Resultsmentioning

confidence: 99%

Submillimeter-wave and far-infrared spectroscopy of high-J transitions of the ground and ν2=1 states of ammonia

Pearson

Drouin

et al. 2010

The Journal of Chemical Physics

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show abstract

“…The observation of a "forbidden" transition in this 2 band with sub-Doppler resolution was reported recently using an infraredinfrared double resonance scheme (1). Now, we extend this IR-IR double resonance investigation to the hyperfine structures of the sP (1,0) and aR(0, 0) transitions of the 2 band. Both the transitions include a rotationless J ϭ 0 level either in the upper 2 excited or in the lower ground vibrational state, so that only one of the monitored levels exhibits the nitrogen quadrupole splitting (the 14 N spin I N ϭ 1).…”

mentioning

confidence: 77%

“…For example, the 2 band of NH 3 was the first to be used for the demonstration of sub-Doppler resolution with a tunable sideband radiation (2). The observation of a "forbidden" transition in this 2 band with sub-Doppler resolution was reported recently using an infraredinfrared double resonance scheme (1). Now, we extend this IR-IR double resonance investigation to the hyperfine structures of the sP (1,0) and aR(0, 0) transitions of the 2 band.…”

mentioning

confidence: 97%

“…in (1)]. For example, the 2 band of NH 3 was the first to be used for the demonstration of sub-Doppler resolution with a tunable sideband radiation (2).…”

mentioning

confidence: 99%

“…The experimental setup has already been described in our previous papers (1,3,4). It consists of a CO 2 laser and of two microwave electrooptic modulators that create two pairs of the independently tunable sidebands.…”

mentioning

confidence: 99%

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