Patent ID: 8487242
Filing Date: 2013-07-16
Classification: H01J

Abstract:
1. A method of analyzing high mass ions in a mass spectrometer comprising the following steps: a) releasing a vacuum in a time of flight mass spectrometer which includes an ionization region, a flight tube and an existing detection unit, where ions formed in the ionization region pass through the flight tube of the time of flight mass spectrometer with an ion flight path and impact the existing detection unit; b) mounting to the existing detection unit of the time of flight mass spectrometer a high mass detection unit including a secondary electron multiplier mounted behind a conversion dynode, where the secondary electron multiplier has a front side and a back side, where the front side of the secondary electron multiplier is proximal to the conversion dynode, where the position of the high mass detection unit is moveable, where the high mass detection unit can be positioned to allow ions to impact the existing detection unit by positioning the high mass detection unit not ‘in-line’, where the high mass detection unit can be positioned to allow ions to impact the high mass detection unit by positioning the high mass detection unit ‘in-line’; c) re-establishing the vacuum in the time of flight mass spectrometer; and d) positioning the high mass detection unit in-line with the ion flight path; e) converting heavy ions which pass through the flight tube of the mass spectrometer with an ion flight path into lighter, secondary ions, by impingement of the heavy ions on the conversion dynode which allows transmission of the secondary ions; f) accelerating the lighter secondary ions towards the secondary electron multiplier by applying a potential difference between the conversion dynode and the front side of the secondary electron multiplier; g) converting the secondary ions into electrons upon impingement of the secondary ions on surfaces of the secondary electron multiplier; and h) multiplying a number of electrons inside the secondary electron multiplier by applying a potential difference between the front side and the back side of the electron multiplier to analyze high mass ions.