Observations on the Interpretation and Analysis of Sulfuric Acid Hydrate Infrared Spectra

Nash, Karen L.; Sully, K. Jessica; Horn, Andrew B.

doi:10.1021/jp0114541

Cited by 50 publications

(40 citation statements)

References 22 publications

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“…Since the electrolyte covers the surface of graphite in the electrolyte region, the spectrum reflects the absorption from the bulk electrolyte rather than from bisulfate species between the layers of graphite. The vibrational shifts from the electrolyte spectrum match well with studies [ 20,24,25 ] on the IR absorption of bisulfate and indicate the presence of O 3 SOH, OSO, SO 3 , and H 3 O + groups. We compared this spectrum to spectra taken in the electrolyte‐free region before and during intercalation as well as after deintercalation (Figure 4b).…”

Section: Figuresupporting

confidence: 82%

“…[ 3,6 ] This system also provides a platform to highlight the advantage of the electrolyte‐free device in the IR. Since the vibrational features of the bisulfate species occur in the mid‐IR [ 20 ] but are overwhelmed by absorption from the electrolyte, the electrolyte‐free geometry enables us to study the absorption of the intercalated bisulfate species in the mid‐IR.…”

Section: Figurementioning

confidence: 99%

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Electrolyte‐Free Spectroscopy and Imaging of Graphite Intercalation

Stark

Cheng

Kim

et al. 2020

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Engineering electrode materials for optoelectronic and energy storage applications requires a fundamental understanding of intercalation using spatially‐resolved techniques. However, spectroscopic methods can have limited spatial resolution and low intensity since the signal passes through electrolyte. Here, a device geometry is presented in which the electrolyte is laterally separated from the area probed spectroscopically, so that the signal does not pass through the electrolyte. This geometry enables us to visualize ion transport with optical microscopy and monitor charge transfer with Raman and visible reflectance spectroscopies. In addition, vibrational changes are probed in the mid‐IR, a region previously difficult to access due to electrolyte absorption. This geometry will allow many layered electrodes to be probed in situ using time‐ and spatially‐resolved techniques, including photon and electron spectroscopies.

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Section: Figuresupporting

confidence: 82%

Section: Figurementioning

confidence: 99%

Electrolyte‐Free Spectroscopy and Imaging of Graphite Intercalation

Stark

Cheng

Kim

et al. 2020

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“…Also shown are homogeneous freezing onset lines calculated according to Koop2000 for nucleation rate coefficients of J V = 10 13 cm −3 s −1 ( a w = 0.32, dashed line) and J V = 5 × 10 8 cm −3 s −1 ( a w = 0.3, dotted line) (Möhler et al, 2003) and corrected according to the revised version of the homogeneous freezing lines by Koop and Zobrist (2009). The earliest freezing experiments with aqueous sulfuric acid solutions at variable solute concentrations and temperatures were performed with macroscopic samples (Ohtake, 1993;Beyer et al, 1994;Song, 1994). The observed onsets deviate significantly from Koop2000 with low water activities close to the melting point curve.…”

Section: Introductionmentioning

confidence: 99%

High homogeneous freezing onsets of sulfuric acid aerosol at cirrus temperatures

et al. 2021

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Abstract. Homogeneous freezing of aqueous solution aerosol particles is an important process for cloud ice formation in the upper troposphere. There the air temperature is low, the ice supersaturation can be high and the concentration of ice-nucleating particles is too low to initiate and dominate cirrus cloud formation by heterogeneous ice nucleation processes. The most common description to quantify homogeneous freezing processes is based on the water activity criterion (WAC) as proposed by Koop et al. (2000). The WAC describes the homogeneous nucleation rate coefficients only as a function of the water activity, which makes this approach well applicable in numerical models. In this study, we investigate the homogeneous freezing behavior of aqueous sulfuric acid aerosol particles by means of a comprehensive collection of laboratory-based homogeneous freezing experiments conducted at the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud simulation chamber, which were conducted as part of 17 measurement campaigns since 2007. The most recent experiments were conducted during October 2020 with special emphasis on temperatures below 200 K. Aqueous sulfuric acid aerosol particles of high purity were generated by particle nucleation in a gas flow composed of clean synthetic air and sulfuric acid vapor, which was added to the AIDA chamber. The resulting chamber aerosol had number concentrations from 30 cm−3 up to several thousand per cubic centimeter with particle diameters ranging from about 30 nm to 1.1 µm. Homogeneous freezing of the aerosol particles was measured at simulated cirrus formation conditions in a wide range of temperatures between 185 and 230 K with a steady increase of relative humidity during each experiment. At temperatures between about 205 K and about 230 K, the AIDA results agree well with the WAC-based predictions of homogeneous freezing onsets. At lower temperatures, however, the AIDA results show an increasing deviation from the WAC-based predictions towards higher freezing onsets. For temperatures between 185 and 205 K, the WAC-based ice saturation ratios for homogeneous freezing onsets increase from about 1.6 to 1.7, whereas the AIDA measurements show an increase from about 1.7 to 2.0 in the same temperature range. Based on the experimental results of our direct measurements, we suggest a new fit line to formulate the onset conditions of homogeneous freezing of sulfuric acid aerosol particles as an isoline for nucleation rate coefficients between 5×108 and 1013 cm−3 s−1. The potential significant impacts of the higher homogeneous freezing thresholds, as directly observed in the AIDA experiments under simulated cirrus formation conditions, on the model prediction of cirrus cloud occurrence and related cloud radiative effects are discussed.

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“…This information can be used to estimate acid concentrations when the acid is contaminated or trapped within a hydrocarbon. The assignment of peak position to species was used, as given in the literature (Nakayama et al, 1999;Nash et al, 2001;Bethell and Sheppard, 1953;Elzinga et al, 2001;Grdadolnik, 2001;Faguy and Marinkovic, 1996).…”

Section: Resultsmentioning

confidence: 99%

FTIR lubricant analysis: Concentration of dispersed sulphuric acid

Sautermeister

Priest

Fox

2014

Industrial Lubrication and Tribology

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Purpose -This paper aims to establish the acid concentration of finely dispersed droplets in hydrocarbon oils. Small quantities of aqueous sulphuric acid (H 2 SO 4 ) were found to be trapped within hydrocarbon shells, making them inaccessible for concentration evaluation by titration. Design/methodology/approach -Fourier transform infrared spectroscopy (FTIR) used in the attenuated total reflection mode (ATR; FTIR-ATR) was applied to study the reaction products of squalane, C 30 H 62 , and an API Group I base oil with various concentrations of aqueous H 2 SO 4 . Findings -The absorbance comparison usually used for estimating acid concentrations was found to fail when small quantities of acid are trapped in the reaction product. It was found that the peak shift and changes in absorbance found for various pure aqueous acid concentrations were useful to establish the remaining concentration of the trapped H 2 SO 4 . Originality/value -This paper fulfils the identified need to study acid dissociation-dependent peak shifts of H 2 SO 4 to find the acid concentration of finely dispersed droplets in hydrocarbon oils.

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Observations on the Interpretation and Analysis of Sulfuric Acid Hydrate Infrared Spectra

Cited by 50 publications

References 22 publications

Electrolyte‐Free Spectroscopy and Imaging of Graphite Intercalation

Electrolyte‐Free Spectroscopy and Imaging of Graphite Intercalation

High homogeneous freezing onsets of sulfuric acid aerosol at cirrus temperatures

FTIR lubricant analysis: Concentration of dispersed sulphuric acid

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