The Ar-Ar lab: Introduction

Where to find us: here
(50° 55.498'N, 13° 19.871'E)

Our lab is equipped with two Argus noble gas mass spectrometers. One machine was developed and built by GV Instruments Ltd. (Manchester, England; now Thermo Scientific), and is in use since summer 2007. This machine is equipped with five Faraday cups for a simultaneous measurement of all five Ar isotopes (36-40). The preperation system connected to this machine was developed in an excellent cooperation with VTS Createc (Germany) and was built and installed by VTS Createc in autum 2006. It consists of a high-temperature resistance furnace (HTC) that allows sample heating and step-wise degassing up to temperatures of 1700 degrees. The special design of the autosampler enables to load samples without wrapping. The furnace is controlled via an Eurotherm controller 3504 that is connected via a serial RS232 interface to the main computer. Also adopted to the prep system is a differentially pumped ZnS viewport from MPF products for CO2 laser heating and degassing (not shown in the figure). Gas cleaning is achieved by two SAES getters, one at room temperature, one at 400 degrees.

Since summer 2007 the HTC is used routinely for step-heating dating of mineral separates and whole rocks. The CO2-Laser (wavelength 10.6 µm), that was delivered by New Wave Research (USA), is in use since beginning of 2008. For laser degassing, we use small mineral fractions (1-30 grains, 0.2 - 2 mg) loaded in a differentially pumped laser viewport that was delivered by MPF products (USA).

Since spring and summer 2008, the HTC and laser step-heating measurements run fully automated. Automation was achieved by combining the powerful IonVantage software package of the Argus with Labview modules that were partly also delivered by GV Instruments and partly self-developed.

The other mass spectrometer is an Argus VI equipped with an additional electron-multiplier at the low-mass side. This machine was built by Thermo Scientific and is used in conjunction with an 193 nm ArF excimer laser developed and installed by Photon Machines, USA. The excimer laser, fully functional since 2009, and the high-sensitivity Argus VI improve the spatial resolution of Ar-Ar dating to the 100 micron scale, and allows to date syn-kinematic phases and dating of authigenic minerals.

J. Pfaender - 2011

since April 2010