Versatile Sub-THz Spectrometer for Trace Gas Analysis

Mouret, G.; Guinet, M.; Cuisset, Arnaud; Croizé, Laurence; Eliet, Sophie; Bocquet, Rachel; Hindle, Francis

doi:10.1109/jsen.2012.2227055

Cited by 34 publications

(31 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They measured the rotational spectrum of 3‐MP with a conventional Stark modulated spectrometer and the analysis revealed the presence of a single conformer while four plausible conformers were expected. In the present work, a frequency multiplication chain was used to measure, at the Doppler limit and at room temperature, pure rotational transitions of 3‐MP in the 70–330 GHz frequency range. In addition, high level of theory DFT and MP2 calculations have been performed to analyse the conformational flexibility of 3‐MP.…”

Section: Figurementioning

confidence: 99%

See 1 more Smart Citation

Full Conformational Landscape of 3‐Methoxyphenol Revealed by Room Temperature mm‐wave Rotational Spectroscopy Supported by Quantum Chemical Calculations

et al. 2018

Self Cite

View full text Add to dashboard Cite

Room temperature millimeter-wave rotational spectroscopy supported by high level of theory calculations have been employed to fully characterise the conformational landscape of 3-Methoxyphenol, a semi-volatile polar oxygenated aromatic compound precursor of secondary organic aerosols in the atmosphere arising from biomass combustion. While previous rotationally-resolved spectroscopic studies in the microwave and in the UV domains failed to observe the complete conformational landscape, the 70-330 GHz rotational spectrum measured in this study reveals the ground state rotational signatures of the four stable conformations theoretically predicted. Moreover, rotational transitions in the lowest energy vibrationally excited states were assigned for two conformers. While the inertial defect of methoxyphenol does not significantly change between conformers and isomers, the excitation of the methoxy out-of-plane bending is the main contribution to the non-planarity of the molecule.

show abstract

Section: Figurementioning

confidence: 99%

“…[20]. The spectral resolution is limited to 100 kHz since the observed lines are Doppler limited (Δ v Doppler

≃

90 kHz (FWHM)) and artificially broadened by the frequency modulation . The experimental error of measured line frequencies was estimated to about 70 kHz using Eq.…”

Section: Figurementioning

confidence: 99%

Full Conformational Landscape of 3‐Methoxyphenol Revealed by Room Temperature mm‐wave Rotational Spectroscopy Supported by Quantum Chemical Calculations

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…The 40 GHz wide part of the mm‐wave spectrum shows this quasi‐continuum of lines polluted by saturated lines due to FP effects (see Section 4.2). The observed lines are Doppler limited (Δ ν Doppler ≈ 80 kHz (FWHM)) and artificially broadened by the frequency modulation that limit the spectral resolution to 100 kHz. In these conditions, most of the measured lines are blended and the 14 N NQC hyperfine structure could not be resolved at high J values .…”

Section: Resultsmentioning

confidence: 99%

“…A continuous flow of 0.8 Pa of the sample, maintained by a roughing pumping, was passed through a 125 cm‐long and 56 mm‐diameter single path stainless steel absorption cell equipped with Teflon windows and probed by the radiation generated by a frequency multiplier chain (Virginia Diodes, Inc). Two off‐axis parabolic mirrors are used to collimate the radiation into the cell and then to refocus it into a liquid‐helium‐cooled InSb bolometer . The spectrum has been recorded in 2F frequency modulation by using a frequency modulation of 10 kHz, 40 kHz modulation depth of the frequencies delivered by the synthesiser, a time constant of 200 ms and 100 kHz frequency steps.…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

Towards the Detection of Explosive Taggants: Microwave and Millimetre‐Wave Gas‐Phase Spectroscopies of 3‐Nitrotoluene

et al. 2018

Self Cite

View full text Add to dashboard Cite

The monitoring of gas-phase mononitrotoluenes is crucial for defence, civil security and environmental interests because they are used as taggant for TNT detection and in the manufacturing of industrial compounds such as dyestuffs. In this study, we have succeeded to measure and analyse at high-resolution a room temperature rotationally resolved millimetre-wave spectrum of meta-nitrotoluene (3-NT). Experimental and theoretical difficulties have been overcome, in particular, those related to the low vapour pressure of 3-NT and to the presence of a CH internal rotation in an almost free rotation regime (V =6.7659(24) cm ). Rotational spectra have been recorded in the microwave and millimetre-wave ranges using a supersonic jet Fourier Transform microwave spectrometer (T <10 K) and a millimetre-wave frequency multiplication chain (T=293 K), respectively. Spectral analysis of pure rotation lines in the vibrational ground state and in the first torsional excited state supported by quantum chemistry calculations permits the rotational energy of the molecule, the hyperfine structure due to the N nucleus, and the internal rotation of the methyl group to be characterised. A line list is provided for future in situ detection.

show abstract

“…RAM distorts the line shapes of the first harmonic signal and the second harmonic signal to an extent [12]- [14]. Some works employed numerical integration and other methods to obtain second harmonic signals for different absorption lines, but did not take into account the RAM effect [15]- [17]. Accurate line shape recovery from WMS spectra suffers from a number of difficulties.…”

Section: Introductionmentioning

confidence: 99%

Continuously Wavelength-Tunable Light Source With Constant-Power Output for Elimination of Residual Amplitude Modulation

et al. 2015

View full text Add to dashboard Cite

A continuously wavelength-tunable light source with constant-power output is presented. The unwanted optical power modulation companying with the wavelength modulation of the distributed feedback laser diode by the injection current is successfully offset by the external amplitude modulation of electro-optic modulator. The optical power stability has been experimentally demonstrated better than 1.2% in a wavelengthtunable range of 0.876 cm −1 . The background baseline appearing in the direct absorption spectrum can be removed with the new light source. Not only that, the spectral distortion of the second harmonic signal caused by residual-amplitude modulation can also be largely eliminated. Experimental results have shown that the new light source is more suitable to be served as a pure wavelength-tuning reference source for different modes of spectroscopic measurement.

show abstract

Versatile Sub-THz Spectrometer for Trace Gas Analysis

Cited by 34 publications

References 16 publications

Full Conformational Landscape of 3‐Methoxyphenol Revealed by Room Temperature mm‐wave Rotational Spectroscopy Supported by Quantum Chemical Calculations

Full Conformational Landscape of 3‐Methoxyphenol Revealed by Room Temperature mm‐wave Rotational Spectroscopy Supported by Quantum Chemical Calculations

Towards the Detection of Explosive Taggants: Microwave and Millimetre‐Wave Gas‐Phase Spectroscopies of 3‐Nitrotoluene

Continuously Wavelength-Tunable Light Source With Constant-Power Output for Elimination of Residual Amplitude Modulation

Contact Info

Product

Resources

About