Comparison of aerosol and thin film spectra of supercooled ternary solution aerosol

McPheat, Robert; Bass, Stephen F.; Newnham, David; Ballard, J.; Remedios, J. J.

doi:10.1029/2001jd000641

Cited by 8 publications

(3 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…So far, only the mixing scheme developed by Biermann et al (2000) permits the calculation of optical constants in the STS system which cover a broad range of compositions and temperatures. However, as recently shown by McPheat et al (2002) on the basis of a measured extinction spectrum of STS aerosols of approximately 21 wt% H 2 SO 4 and 12 wt% HNO 3 at around 182 K, the Mie calculation using the Biermann et al (2000) optical constants differed significantly from the experimental spectrum in the important 750-1300 cm −1 region. They proposed that the temperature dependence of the sulphate feature in this regime might explain the poor Mie fit, since the H 2 SO 4 /H 2 O binary optical constants needed in the mixing scheme to calculate the ternary refractive indices were only measured down to 253 K. But note that the calculation of the ternary refractive indices of STS particles with 21 wt% H 2 SO 4 and 12 wt% HNO 3 using the Biermann et al (2000) mixing rule does not require optical constants for a binary solution containing 21 wt% H 2 SO 4 (which were in fact only measured down to 253 K), but for a binary solution containing 33 wt% H 2 SO 4 (corresponding to 21 wt% H 2 SO 4 +12 wt% HNO 3 in the ternary STS particles) which is accessible down to 193 K in the data base of Biermann et al (2000).…”

Section: Discussionmentioning

confidence: 80%

A quantitative test of infrared optical constants for supercooled sulphuric and nitric acid droplet aerosols

Wagner¹,

Mangold

Möhler³

et al. 2003

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. In situ Fourier transform infrared (FTIR) extinction spectra of supercooled H 2 SO 4 /H 2 O and HNO 3 /H 2 O solution droplets were recorded in the large coolable aerosol chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere) of Forschungszentrum Karlsruhe for a range of aerosol compositions and at temperatures extending down to 192 K. The measured spectra were quantitatively analysed in terms of aerosol composition and mass concentration by using Mie theory in combination with published refractive index data as input parameters. Simultaneously, total sulphuric acid and nitric acid mass concentrations from filter analysis and total water concentrations measured with the Lyman-α hygrometer of Forschungszentrum Jülich were used to calculate the aerosol composition at thermodynamic equilibrium inside the aerosol chamber. By comparing these measured aerosol parameters with those retrieved from the analysis of the FTIR spectra, the accuracy of the literature data sets of refractive indices could be assessed. In summary, four data sets were tested in the H 2 SO 4 /H 2 O system as well as two data sets in the HNO 3 /H 2 O system, partly revealing significant discrepancies in the retrieved aerosol properties. Potential explanations for these differences are discussed in this paper.

show abstract

Section: Discussionmentioning

confidence: 80%

A quantitative test of infrared optical constants for supercooled sulphuric and nitric acid droplet aerosols

Wagner¹,

Mangold

Möhler³

et al. 2003

Atmos. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…Physical properties of both HNO 3 and H 2 SO 4 solutions [2] under stratospheric conditions are previously carried out. Infrared optical constants of this ternary system for different mixtures of H 2 SO 4 and HNO 3 solutions [3][4][5] are evaluated at stratospheric temperature range [6][7][8][9] from 183 K to 293 K. Furthermore, four data sets are tested in the H 2 SO 4 /H 2 O system as well as two data sets in the HNO 3 /H 2 O system [10][11][12][13] revealing partly significant discrepancies in aerosol properties with those parameters recovered from FTIR spectra in the literature data. Rapid temperature fluctuations are shown to cause liquid H 2 SO 4 /HNO 3 /H 2 O stratospheric aerosols [14] to depart considerably from thermodynamic equilibrium.…”

Section: Introductionmentioning

confidence: 96%

Facet shapes and thermo-stabilities of H2SO4•HNO3 hydrates involved in polar stratospheric clouds

Verdes

Paniagua

2015

J Mol Model

View full text Add to dashboard Cite

The nucleation, ice crystal shapes and thermodynamic stability of polar stratospheric clouds particles are interesting concerns owing to their implication in the ozone layer destruction. Some of these particles are formed by conformers of H2O, HNO3, and H2SO4. We carried out calculations using density functional theory (DFT) to obtain optimized structures. Several stable trimers are achieved -divided in two groups, one with HNO3 moiety, second with H2SO4 moiety- after pre-optimization at B3LYP/6-31G and subsequently optimization at B3LYP/aug-cc-pVTZ level of theory. For both most stable conformers five H2O molecules are added to their optimized trimers to calculate hydrated geometries. The OH stretching harmonic frequencies are provided for all aggregates. The zero-point energy correction (ZEPC), relative electronic energies (∆E), relative reaction Gibbs free energies ∆(∆G)k-relative, and cooling constant (K cooling ) are reported at three temperatures: 188 K, 195 K, and 210 K. Shapes given in our calculations are compared with various experimental shapes as well as comparisons with their thermo-stabilities.

show abstract

“…This approach has already been implemented in several retrieval algorithms in remote sensing applications. , However, there is still a need for an independent study to assess the accuracy by which FTIR extinction spectra of STS aerosols can be analyzed in terms of aerosol composition and mass concentration on the basis of this mixing rule. McPheat et al have observed large spectral differences between a measured STS droplet extinction spectrum and a Mie calculation using the Biermann et al mixing rule in the 750−1300 cm -1 spectral region. However, this must not be a result of a deficiency of the mixing rule but may be fully explained by the poor quality of the Biermann et al binary data sets, which were employed in the mixing rule calculation.…”

Section: Introductionmentioning

confidence: 99%

Aerosol Chamber Study of Optical Constants and N₂O₅ Uptake on Supercooled H₂SO₄/H₂O/HNO₃ Solution Droplets at Polar Stratospheric Cloud Temperatures

Wagner¹,

Naumann²,

Mangold³

et al. 2005

J. Phys. Chem. A

View full text Add to dashboard Cite

The mechanism of the formation of supercooled ternary H(2)SO(4)/H(2)O/HNO(3) solution (STS) droplets in the polar winter stratosphere, i.e., the uptake of nitric acid and water onto background sulfate aerosols at T < 195 K, was successfully mimicked during a simulation experiment at the large coolable aerosol chamber AIDA of Forschungszentrum Karlsruhe. Supercooled sulfuric acid droplets, acting as background aerosol, were added to the cooled AIDA vessel at T = 193.6 K, followed by the addition of ozone and nitrogen dioxide. N(2)O(5), the product of the gas phase reaction between O(3) and NO(2), was then hydrolyzed in the liquid phase with an uptake coefficient gamma(N(2)O(5)). From this experiment, a series of FTIR extinction spectra of STS droplets was obtained, covering a broad range of different STS compositions. This infrared spectra sequence was used for a quantitative test of the accuracy of published infrared optical constants for STS aerosols, needed, for example, as input in remote sensing applications. The present findings indicate that the implementation of a mixing rule approach, i.e., calculating the refractive indices of ternary H(2)SO(4)/H(2)O/HNO(3) solution droplets based on accurate reference data sets for the two binary H(2)SO(4)/H(2)O and HNO(3)/H(2)O systems, is justified. Additional model calculations revealed that the uptake coefficient gamma(N(2)O(5)) on STS aerosols strongly decreases with increasing nitrate concentration in the particles, demonstrating that this so-called nitrate effect, already well-established from uptake experiments conducted at room temperature, is also dominant at stratospheric temperatures.

show abstract

Comparison of aerosol and thin film spectra of supercooled ternary solution aerosol

Cited by 8 publications

References 15 publications

A quantitative test of infrared optical constants for supercooled sulphuric and nitric acid droplet aerosols

A quantitative test of infrared optical constants for supercooled sulphuric and nitric acid droplet aerosols

Facet shapes and thermo-stabilities of H2SO4•HNO3 hydrates involved in polar stratospheric clouds

Aerosol Chamber Study of Optical Constants and N₂O₅ Uptake on Supercooled H₂SO₄/H₂O/HNO₃ Solution Droplets at Polar Stratospheric Cloud Temperatures

Contact Info

Product

Resources

About

Comparison of aerosol and thin film spectra of supercooled ternary solution aerosol

Cited by 8 publications

References 15 publications

A quantitative test of infrared optical constants for supercooled sulphuric and nitric acid droplet aerosols

A quantitative test of infrared optical constants for supercooled sulphuric and nitric acid droplet aerosols

Facet shapes and thermo-stabilities of H2SO4•HNO3 hydrates involved in polar stratospheric clouds

Aerosol Chamber Study of Optical Constants and N2O5 Uptake on Supercooled H2SO4/H2O/HNO3 Solution Droplets at Polar Stratospheric Cloud Temperatures

Contact Info

Product

Resources

About

Aerosol Chamber Study of Optical Constants and N₂O₅ Uptake on Supercooled H₂SO₄/H₂O/HNO₃ Solution Droplets at Polar Stratospheric Cloud Temperatures