Investigation Into the Spatial Elemental Distribution Within a Pane of Glass by Time of Flight Secondary Ion Mass Spectrometry

• NCJ Number: 222341
• Journal: Journal of Forensic Sciences Volume: 53 Issue: 2 Dated: March 2008 Pages: 312-320
• Author(s): John Coumbaros Ph.D.; John Denman B.Sc.; K. Paul Kirkbride Ph.D.; G. Steward Walker Ph.D.; William Skinner Ph.D.
• Date Published: March 2008
• Length: 9 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

Since advances in technology have led to a uniform manufacturing process for glass, glass products have little variability in their physical and optical properties, this study describes the three-dimensional homogeneity of a sheet of float glass and explores the consequences for the forensic elemental analysis of small glass particles.

Abstract

The findings confirm that the refractive index (RI) of both the float and nonfloat surfaces differed significantly from the RI of the bulk. These finding support the practice of avoiding float surface fragments, which are easily distinguished, when measuring RI. The study also found that the analysis of nonfloat surface fragments was not straightforward, since their RI and elemental composition was not representative of the bulk. This is significant, because nonfloat surface fragments are not as easily recognized as float surface fragments. These findings confirm other studies that have concluded there is no significant variation in RI and elemental composition across the pane with reference to fragments recovered from the bulk (i.e., by avoiding surface fragments). The variation in elemental composition shown in this study is not a concern if analytical conditions are such that the glass surface is sampled to a depth beyond a few microns. Researchers are continuing in their effort to describe the extent of tin diffusion in the float surface and its impact upon elemental composition of glass. Clear window float glass (nontempered) 100 x 100 cm, 3 mm thick, was purchased from a glass manufacturer in Adelaide, South Australia. The supplier indicated the sample to be a typical sheet of float glass supplied for window glass in Adelaide. A description of the material and methods addresses the characteristics of the glass samples, glass sampling for RI analysis, glass sampling for analysis with time-of-flight secondary ion mass spectrometry, and instrumental parameters. 9 figures and 45 references