Raman band contours for water vapor as a function of temperature

Abstract

A simplified method of calculation of the contour of a totally polarized Raman band for an asymmetric top molecule in the gaseous state has been applied to produce the first accurate band-shape calculation for the ν1 band of the water molecule. The good fits between computed and experimental contours from approximately 150 to 350 °C lay the foundation for temperature determination for water vapor from measurements of the Raman band profile and for density measurements independent of the temperature.

Vapor pressure and specific electrical conductivity in the solid and molten H2O-CsH2PO4-CsPO3 system—a novel electrolyte for water electrolysis at ~ 225–400 °C

“…The scattering cross section ratios, σ H2O /σ N2 or σ H2O /σ CH4 between water and nitrogen or water and methane gas molecule Q-branch areas, as defined above, respectively, take values at around ∼3.50 or ∼0.40, respectively, as determined previously [80], rather independently of temperature [94], although some deviations from these values were seen in older literature. be determined.…”

Water vapor pressure over molten KH2PO4 and demonstration of water electrolysis at ∼300 °C

“…The CH 4 or H 2 Raman bands can be used as internal intensity standard calibration signals, making it possible to quantify the water content by means of the intensity [16], as discussed in detail in [14] and [17][18][19]. In spite of the rather weak scattering strength, the Raman spectroscopy technique is a favorable method to determine the content of gases trapped in voids, because the signals are species-specific and the signal (intensity) should be linearly dependent on the species concentration.…”

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

“…Our data seem not precise enough to warrant the use of temperature dependent scattering ratios, in agreement with what was found for the water vapor ν 1 band contour up to 348 ℃. 18…”

“…The water asymmetric top molecule of C 2v symmetry has a well-known Stokes Raman spectrum consisting of three active fundamental transitions: n 1 (symmetrical O-H bond stretching), n 2 (symmetrical H-O-H angle bending), and n 3 (asymmetrical O-H bond stretching). [18][19][20][21][22][23] The n 1 band is relatively strong; the other ones are very weak in Raman. Infrared absorption is much more intense but has the problem of the strong absorption of common window materials.…”

“…It can be seen that the band envelope at ∼3655 cm -1 looks like what would be expected from a broadened band of a shape reminding of the H 2 O spectra in the literature. [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 )…”