Counting individual ions by tagging them with nanoparticles | Abstract
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Counting individual ions by tagging them with nanoparticles

Author(s): Boris Gorbunov and Michael Burton

The quantification of ultra-low concentrations of molecules and ions in gases is of fundamental and practical importance for science and technology, for example, the detection of explosives in airports or biomarkers in medical diagnostics. Often the Faraday cup is employed to transfer ion concentrations in an electric current that is then amplified and measured. One of the main challenges is to increase the sensitivity of detection. A novel concept has been developed that enables detection of individual ions in gases by tagging them with neutral nano-objects. The concentration of ionized molecules was measured and a detection limit of 5 cm -3 was observed. It is anticipated that this concept opens doors for advances in detection sensitivity for many applications including security, medical diagnostic, trace chemical analysis.

A novel concept of measuring the concentration of ionized molecules in gases that enables detection of individual ionized molecules by means of tagging them with readily detectable nanoobjects has been discovered. It was found that this method where ions were tagged with electrically neutral objects, e.g. nanoparticles with radius 100 nm, can provide a breakthrough in sensitivity by enabling a single ion or electron to be detected. This provides an increase in sensitivity by three order of magnitude in comparison to existing methods. This concept was termed Individual Ion Tagging (IIT).