Titre du document / Document title

Thermal decomposition of humboldtine: A high resolution thermogravimetric and hot stage Raman spectroscopic study

Auteur(s) / Author(s)

FROST R. L. ⁽¹⁾ ; WEIER M. L. ⁽¹⁾ ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾ Inorganic Materials Research Program, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001, AUSTRALIE

Résumé / 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.

Revue / Journal Title

Journal of thermal analysis and calorimetry   ISSN 1388-6150 

Source / Source

2004, vol. 75, n^o1, pp. 277-291 [15 page(s) (article)] (58 ref.)

Langue / Language

Anglais

Editeur / Publisher

Springer, Dordrecht, PAYS-BAS  (1998) (Revue)

Mots-clés anglais / English Keywords

Infrared spectrometry ; Raman spectrometry ; Thermogravimetry ; Thermal analysis ; Iron II Oxalate ; Pyrolysis ;

Mots-clés français / French Keywords

Humboldtine ; Spectrométrie IR ; Spectrométrie Raman ; Thermogravimétrie ; Analyse thermique ; Fer II Oxalate ; Pyrolyse ;

Mots-clés espagnols / Spanish Keywords

Espectrometría IR ; Espectrometría Raman ; Termogravimetría ; Análisis térmico ; Hierro II Oxalato ; Pirólisis ;

Mots-clés d'auteur / Author Keywords

high resolution thermogravimetric analysis ; hot stage Raman spectroscopy ; humboldtine ; infrared emission spectroscopy ; oxalate ;

Localisation / Location

INIST-CNRS, Cote INIST : 6367, 35400011644557.0260