THE INFLUENCE OF HYPERFINE STRUCTURE AND ISOTOPE SHIFT ON THE DETECTION OF RB ATOMS IN ATMOSPHERIC PRESSURE ATOMIZERS BY THE 2F-WAVELENGTH MODULATION TECHNIQUE

摘要

An investigation of the influence of hyperfine structure and isotope shift on the 2f-wavelength modulation (2f-WM) signal from Rb atoms in low pressure cells and atmospheric pressure reservoirs (e.g. graphite furnaces) has been performed. Simulations of the signal generation process of the 2f-WM technique for detection of Rb atoms on the 780 nm transition based upon a simple one-peak modelling of the Rb atom (including collision induced shifts and broadening) have been compared with those based upon a full modelling of the hyperfine structure and isotope shifts (encompassing 12 transitions). It is found that the 2f-WM signals are significantly affected by the detailed atomic structure. The signals from the one-peak description are generally in poor agreement with those from the more realistic 12-peaks description in low pressure cells. The agreement is better, but still not fully satisfactory, for atoms in atmospheric pressure reservoirs. There is also a significant difference between the 2f-WM signals from low pressure cells and atmospheric pressure atomizers. Hence, it is concluded that it is far from trivial to use a low pressure cell for finding the optimum conditions for detection of Rb atoms in atmospheric pressure atomizers using the 2f-WM technique. A strategy for finding the optimum conditions for detection of Rb atoms in atmospheric pressure atomizers by the 2f-WM technique based upon signals from a low pressure cell is given. (C) 1997 Elsevier Science B.V. [References: 14]