Resolution of overlapping mid-infrared spectra using SIMPLISMA and a second-order derivative approach

• Published in: Vibrational spectroscopy Vol. 10; no. 2; pp. 125 - 138
• Main Authors: Toft, J., Cuesta Sánchez, F., van den Bogaert, B., Libnau, F.O., Massart, D.L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1996
• Subjects: Infrared spectrometry; Mid-infrared spectrometry; Overlapping spectra; Second order derivative; SIMPLISMA; Infrared spectrometry; Mid-infrared spectrometry; SIMPLISMA; Second order derivative; Overlapping spectra
• ISSN: 0924-2031; 1873-3697
• DOI: 10.1016/0924-2031(95)00035-6

Matrices of severely overlapping mid-infrared mixture spectra have been resolved into the pure compounds' spectra and concentration profiles using SIMPLISMA and a 2nd order derivative approach. For a three-compound mixture system of organic solvents, SIMPLISMA qualitatively resolves the spectra satisfactorily while it provides only semi-quantitative concentrations. Quantitative results are obtained by applying an additional iterative procedure. Applied to water spectra acquired in the temperature range 2–96°C, SIMPLISMA resolves two spectra. Using a discrete model, these spectra can be interpreted as corresponding to water structures constructed of H 2O molecules with a relatively high and low average number of H-bonds. After an optimising procedure the estimated enthalpy was 2.3 kcal mol −1, which is in accordance with figures found in literature.