Raman Spectroscopic Studies of Methane—Ethane Mixtures as a Function of Pressure

Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan

doi:10.1366/0003702011952442

Cited by 47 publications

(24 citation statements)

References 10 publications

(9 reference statements)

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“…The narrowband third harmonic and frequency-doubled OPA spectra, in the case of methane (Fig. 2(a)-(b)) are separated by ν R = 2920 cm -1 detuning resonant to the C-H symmetric stretching in CH 4 [6]. In the case of measurements in air shown in Fig.…”

mentioning

confidence: 88%

“…Although picosecond pump and Stokes pulses possess substantially broader spectra (corresponding convolution of pump and Stokes spectra is in the order of 37 cm -1 ( Fig. 2(a)) as compared to the bandwidth of Raman response (<2 cm -1 in the case of CH 4 [6]), due to the fact that the spectral width of both pulses is comparable, our setup has rather high sensitivity. As it can be seen from Fig.…”

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confidence: 97%

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Ultrafast-laser-induced backward stimulated Raman scattering for tracing atmospheric gases

Malevich¹,

Kartashov²,

Zou³

et al. 2012

Opt. Express

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Abstract. By combining tunable broadband pulse generation with nonlinear spectral compression, we demonstrate a prototype scheme for highly selective coherent standoff sensing of air molecules and discuss its coupling to the recently demonstrated backward atmospheric lasing.Many applications in environmental science and security call for standoff chemical identification of airborne pollutants by their signature molecular vibrations. Raman LIDARs, relying on the observation of incoherent wide-angle scattering, have limitations in their practicability. The success of heterodyne detection as a cornerstone concept of the existing coherent LIDAR approaches motivate the development of optical remote sensing schemes where the coherence would be used to provide a highly directional backward optical signal through stimulated Raman scattering, thus enhancing the sensitivity and selectivity of standoff detection. Coherently-enhanced Raman scattering processes, such as Coherent Anti-Stokes Raman Scattering (CARS) and Stimulated Raman Scattering (SRS), open the possibility of recording signals carried in a laser-like beam. Generation of a backward phase-matched Raman signal is simple in the presence of reflective or diffuse objects capable of bouncing the laser beam back. However, an observer who sends out a laser pulse to interrogate an optically transparent atmosphere has to find an alternative way of initiating a backward-propagating laser beam and to solve the problem of phase matching. The recent experimental demonstration of a remotely pumped atmospheric backward laser using O 2 (λ=845 nm) [1] or N 2 (λ=337 and 357 nm) [2] has sparked proposals for coherent standoff Raman spectroscopies [3].In this work we experimentally and theoretically investigate a prototype for SRS in air which will be ultimately based on the 337-nm atmospheric N 2 laser (Fig.1a). The interim model (Fig.1b) is based on a solid-state ultrafast laser system from which we derive a narrowband third harmonic Stokes pulse at ~340 nm, imitating the N 2 laser emission, and a synchronized tunable narrowband EPJ Web of Conferences

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confidence: 88%

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confidence: 97%

Ultrafast-laser-induced backward stimulated Raman scattering for tracing atmospheric gases

Malevich¹,

Kartashov²,

Zou³

et al. 2012

Opt. Express

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“…[18][19][20][21][22][23] Calibration spectra of internal standard gasses for quantitative determination of the water are also shown in Figure 3, for the examples of methane to the left or hydrogen to the right. The methane gas phase spectrum contains the well-known [24][25][26][27][28] ro-vib Q-branch band structure of the ν 1 (A 1 )…”

Section: -23mentioning

confidence: 99%

Determination of Water Vapor Pressure Over Corrosive Chemicals Versus Temperature Using Raman Spectroscopy as Exemplified with 85.5% Phosphoric Acid

Rodier

Berg

et al. 2016

Appl Spectrosc

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A method to determine the water vapor pressure over a corrosive substance was developed and tested with 85.5 ± 0.4 % phosphoric acid. The water vapor pressure was obtaineded at a range of temperatures from ∼25 °C up to ∼200 °C using Raman spectrometry. The acid was placed in an ampoule and sealed with a reference gas (either hydrogen or methane) at a known pressure (typically ∼0.5 bar). By comparing the Raman signals from the water vapor and the references, the water pressure was determined as a function of temperature. A considerable amount of data on the vapor pressure of phosphoric acid is available in the literature, to which our results could successfully be compared. A record value of the vapour pressure, 3.40 bar, was determined at 210 °C. The method required a determination of the precise Raman scattering ratios between the substance: water and the used reference gas: hydrogen or methane. In our case the scattering ratios between water and reference ν 1 Q-branches were found to be 1.20 ± 0.03 and 0.40 ± 0.02 for H 2 and CH 4 , respectively.

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“…These interesting properties have initiated numerous studies, including preparation, stability investigation and determination of the chemical composition [3]. The structure of the solid hydrate and different methane-water clusters was also subject of extensive theoretical [4][5][6][7][8][9][10][11], and spectroscopic studies [12][13][14][15][16][17][18][19]. A main concern for the computational studies was to create a proper potential for molecular dynamics calculations [4,5,7,8], and to determine the hydratation number of methane.…”

Section: Introductionmentioning

confidence: 99%

DFT study of possible lattice defects in methane-hydrate and their appearance in 13C NMR spectra

Terleczky

Nyulászi

2010

Chemical Physics Letters

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Raman Spectroscopic Studies of Methane—Ethane Mixtures as a Function of Pressure

Cited by 47 publications

References 10 publications

Ultrafast-laser-induced backward stimulated Raman scattering for tracing atmospheric gases

Ultrafast-laser-induced backward stimulated Raman scattering for tracing atmospheric gases

Determination of Water Vapor Pressure Over Corrosive Chemicals Versus Temperature Using Raman Spectroscopy as Exemplified with 85.5% Phosphoric Acid

DFT study of possible lattice defects in methane-hydrate and their appearance in 13C NMR spectra

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