Thermal decomposition of humboldtine - a high resolution thermogravimetric and hot stage Raman spectroscopic study

Frost, Ray L. and Weier, Matt L. (2004) Thermal decomposition of humboldtine - a high resolution thermogravimetric and hot stage Raman spectroscopic study. Journal of Thermal Analysis and Calorimetry, 75(1). pp. 277-291.

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DOI: 10.1023/B:JTAN.0000017349.31035.dd

Abstract

Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates. These oxalates form as a film like deposit on rocks and other host matrices. Humboldtine as the natural iron(II) oxalate mineral is a classic example. Thermogravimetry coupled to evolved gas mass spectrometry shows dehydration takes place in two steps at 130 and 141 °C. Loss of the oxalate as carbon dioxide occurs at 312 and 332 °C. Dehydration is readily followed by Raman microscopy in combination with a thermal stage and is observed by the loss of intensity of the OH stretching vibration at 3318 cm-1. The application of infrared emission spectroscopy supports the results of the TG-MS. Three Raman bands are observed at 1470, 1465 and 1432 cm-1 attributed the CO symmetric stretching mode. The observation of the three bands supports the concept of multiple iron(II) oxalate phases. The significance of this work rests with the ability of Raman spectroscopy to identify iron(II)oxalate which often occurs as a film on a host rock.

ID Code:	838
Item Type:	Journal Article
Keywords:	oxalate, humboldtine, high resolution thermogravimetric analysis, hot stage Raman spectroscopy, infrared emission spectroscopy
ISSN:	1572-8943
Subjects:	Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > INORGANIC CHEMISTRY (030200)
Divisions:	QUT Faculties and Divisions > Faculty of Science and Technology
Copyright Owner:	Copyright 2004 Springer
Copyright Statement:	The original publication is available at SpringerLink.
Deposited On:	14 Mar 2005
Last Modified:	23 Jan 2009 02:14

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