GGR Handbook of Rock and Mineral Analysis Chapter 23 Thermal Ionisation Mass Spectrometry

Abstract

This chapter (Thermal Ionisation Mass Spectrometry) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of A Handbook of Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).

Chapter 23 (from Section 4 of the handbook dealing with techniques for age determination and isotope ratio measurement) describes how ions are formed in the source of a TIMS instrument, how they are accelerated through the analyser and separated according to their mass/charge ratios, and how the resulting ion beams are measured in the collector. Throughout the chapter, the specificities of thermal ionisation mass spectrometry are emphasised. A particular emphasis is placed on understanding the thermal ionisation process for both positive and negative ions and how it is influenced by factors such as sample deposition. Recent advances in detection systems, such as the development of amplifiers with 10¹³-Ω resistors and capacitance-type amplifiers, and in focusing systems (lenses, zoom optics, etc.) are reviewed. The chapter concludes with an overview of both established and more innovative TIMS applications.