Journal article
Molar Absorptivity Measurements in Absorbing Solvents: Impact on Solvent Absorptivity Values
Applied spectroscopy, Vol.71(3), pp.446-455
03/2017
DOI: 10.1177/0003702816662883
PMID: 27756864
Abstract
Molar absorptivity is a fundamental molecular property that quantifies absorption strength as a function of wavelength. Absolute measurements of molar absorptivity demand accounting for all mechanisms of light attenuation, including reflective losses at interfaces associated with the sample. Ideally, such measurements are performed in nonabsorbing solvents and reflective losses can be determined in a straightforward manner from Fresnel equations or effectively accounted for by path length difference methods. At near-infrared wavelengths, however, many solvents, including water, are absorbing which complicates the quantification of reflective losses. Here, generalized equations are developed for calculating absolute molar absorptivities of neat liquids wherein the dependency of reflective loss on absorption properties of the liquid are considered explicitly. The resulting equations are used to characterize sensitivity of absolute molar absorptivity measurements for solvents to the absorption strength of the solvent as well as the path length of the measurement. Methods are derived from these equations to properly account for reflective losses in general and the effectiveness of these methods is demonstrated for absolute molar absorptivity measurements for water over the combination region (5000-4000 cm ) of the near-infrared spectrum. Results indicate that ignoring solvent absorption effects can incorporate wide ranging systematic errors depending upon experimental conditions. As an example, systematic errors range from 0 to 10% for common conditions used in the measurement of absolute molar absorptivity of water over the combination region of the near-infrared spectrum.
Details
- Title: Subtitle
- Molar Absorptivity Measurements in Absorbing Solvents: Impact on Solvent Absorptivity Values
- Creators
- Ariel Bohman - Department of Chemistry and Optical Science and Technology Center, University of Iowa, USAMark A Arnold - Department of Chemistry and Optical Science and Technology Center, University of Iowa, USA
- Resource Type
- Journal article
- Publication Details
- Applied spectroscopy, Vol.71(3), pp.446-455
- Publisher
- United States
- DOI
- 10.1177/0003702816662883
- PMID
- 27756864
- ISSN
- 0003-7028
- eISSN
- 1943-3530
- Language
- English
- Date published
- 03/2017
- Academic Unit
- Center for Biocatalysis and Bioprocessing; Fraternal Order of Eagles Diabetes Research Center; Chemistry
- Record Identifier
- 9983985940602771
Metrics
29 Record Views