Wavenumber calibration tables from heterodyne frequency measurements

Maki, Arthur G.; Wells, J. S.

doi:10.6028/nist.sp.821

Cited by 237 publications

(157 citation statements)

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“…Some of the mid-infrared water studies predated the better accuracy calibration standards [89,90]. At longer wavelengths, adjustments were made to resolve inconsistencies noticed during the MARVEL analysis (see Table 4 of Part III).…”

Section: Levels and Linesmentioning

confidence: 99%

A database of water transitions from experiment and theory (IUPAC Technical Report)

Tennyson

Bernath

Brown

et al. 2014

Pure and Applied Chemistry

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Abstract:The report and results of an IUPAC Task Group (TG) formed in 2004 on "A Database of Water Transitions from Experiment and Theory" (Project No. 2004-035-1-100) O, are determined from measured transition frequencies. The transition frequencies and energy levels are validated using first-principles nuclear motion computations and the MARVEL (measured active rotational-vibrational energy levels) approach. The extensive data including lines and levels are required for analysis and synthesis of spectra, thermochemical applications, the construction of theoretical models, and the removal of spectral contamination by ubiquitous water lines. These datasets can also be used to assess where measurements are lacking for each isotopologue and to provide accurate frequencies for many yet-to-be measured transitions. The lack of high-quality frequency calibration standards in the near infrared is identified as an issue that has hindered the determination of high-accuracy energy levels at higher frequencies. The generation of spectra using the MARVEL energy levels combined with transition intensities computed using high accuracy ab initio dipole moment surfaces are discussed. A recommendation of the TG is for further work to identify a single, suitable model to represent pressure-(and temperature-) dependent line profiles more accurately than Voigt profiles.

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Section: Levels and Linesmentioning

confidence: 99%

A database of water transitions from experiment and theory (IUPAC Technical Report)

Tennyson

Bernath

Brown

et al. 2014

Pure and Applied Chemistry

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“…3) at 1879:386 cm ÿ1 . This line consists of a multiplet of 10 hyperfine transitions [10]. The feature can be fitted to Lorentzian profiles of these transitions while we take into account the increased -type doubling.…”

Section: H Y S I C a L R E V I E W L E T T E R S Week Ending 18 Novemmentioning

confidence: 99%

“…Infrared radiation is generated by means of a lead salt laser diode. Frequency calibration is achieved by simultaneously measuring the absorption lines of 20 mbar carbonyl sulfide in a cell whose frequencies are well known [7]. The laser beam also passes through a confocal etalon in order to linearize the spectrum.…”

mentioning

confidence: 99%

High-Resolution Spectroscopy of NO in Helium Droplets: A Prototype for Open Shell Molecular Interactions in a Quantum Solvent

Haeften

Metzelthin²,

Rudolph³

et al. 2005

Phys. Rev. Lett.

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We have measured the high-resolution infrared spectrum of the radical NO in the 2 1=2 state in superfluid helium nanodroplets. The features are attributed to the -doubling splitting and the hyperfine structure. The hyperfine interaction is found to be unaffected by the He solvation. For the -doubling splitting, we find a considerable increase by 55% compared to the gas phase. This is explained by a confinement of the electronically excited NO states by the surrounding He. The rotational level spacing is decreased to 76% of the gas phase value. The IR transition to the J 1:5 state is found to be homogeneously broadened. We attribute both observations to the coupling between the molecular rotation and phonon/roton excitations in superfluid 4 He droplets. DOI: 10.1103/PhysRevLett.95.215301 PACS numbers: 67.40.Fd, 33.15.Pw, 33.20.Ea, 33.20.Wr Spectroscopy of molecules in He nanodroplets is a very promising technique for investigating chemical reactions at ultralow temperatures. In such reactions, radicals play an important role [1]. It is, therefore, of interest to probe the influence of the He environment on a radical. While at present quite a number of closed shell molecules have been studied in He droplets [2], only little is known about the influence of the helium droplets on the spectra [3] and the electronic structure of radicals. The infrared spectra of many radicals exhibit hyperfine splitting and -type doubling. These effects are well known in the gas phase but have never been studied in solvents.In this Letter, we report the measurement of the IR spectrum of NO in He droplets. NO is an open shell molecule and has a 2 1=2 electronic ground state. The rotational levels of NO show hyperfine structure and -type doubling. While the hyperfine splitting reflects the magnetic interaction, -type doubling arises from rotational interaction of the ground state with higher electronic states. The coupling to the higher electronic or ÿ states splits the degenerate energy levels of the 2 1=2ground state. We will show that the droplets increase the magnitude of the -type doubling and discuss the implications for the electronically excited states of NO within the He solvent. The lower rotational energy levels of NO lie in the interesting region of the collective excitations of superfluid He. In particular, they are close to the roton excitations. NO is therefore a good candidate to investigate the role of these excitations in the rotational energy relaxation or in the shift of the rotational levels, as recently pointed out by theory [4,5]. For this purpose, NO as a diatomic molecule is ideal because it has only a single vibrational mode. The vibrational energy is much larger than the collective excitations of liquid He (1875 cm ÿ1 10 cm ÿ1 ). Therefore, vibrational relaxation is extremely slow.The experiments have been carried out using a new apparatus at Bochum. The setup is similar to that used by Hartmann et al. and explained in detail elsewhere [5,6]. Here we give only a brief description. Helium is expanded at 40 ...

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“…Infrared radiation is generated by means of a lead salt laser diode (Laser Components). Frequency calibration is achieved by simultaneously measuring the absorption lines of about 10 mbar NO at room temperature in a cell, whose frequencies are well known [7]. The laser beam also passes through a confocal etalon in order to linearize the spectrum.…”

Section: Methodsmentioning

confidence: 99%

Observation of the R(0.5)²Π_1/2transition of¹⁵N¹⁸O in helium nanodroplets

Metzelthin¹,

Havenith²

2007

Molecular Physics

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Wavenumber calibration tables from heterodyne frequency measurements

Cited by 237 publications

References 0 publications

A database of water transitions from experiment and theory (IUPAC Technical Report)

A database of water transitions from experiment and theory (IUPAC Technical Report)

High-Resolution Spectroscopy of NO in Helium Droplets: A Prototype for Open Shell Molecular Interactions in a Quantum Solvent

Observation of the R(0.5)²Π_1/2transition of¹⁵N¹⁸O in helium nanodroplets

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Wavenumber calibration tables from heterodyne frequency measurements

Cited by 237 publications

References 0 publications

A database of water transitions from experiment and theory (IUPAC Technical Report)

A database of water transitions from experiment and theory (IUPAC Technical Report)

High-Resolution Spectroscopy of NO in Helium Droplets: A Prototype for Open Shell Molecular Interactions in a Quantum Solvent

Observation of the R(0.5)2Π1/2transition of15N18O in helium nanodroplets

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Observation of the R(0.5)²Π_1/2transition of¹⁵N¹⁸O in helium nanodroplets