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Kinetic‐energy‐sensitive mass spectrometry for separation of different ions with the same m / z value
Author(s) -
Shiki Shigetomo,
Ukibe Masahiro,
Sato Yuki,
Tomita Shigeo,
Hayakawa Shigeo,
Ohkubo Masataka
Publication year - 2008
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1459
Subject(s) - chemistry , ion , homonuclear molecule , ionization , kinetic energy , mass spectrometry , diatomic molecule , atomic physics , analytical chemistry (journal) , electron ionization , molecule , physics , organic chemistry , chromatography , quantum mechanics
A double‐focusing mass spectrometer (MS) equipped with a superconducting‐tunnel‐junction (STJ) detector has been applied to measure relative ionization cross‐sections for the production of ions that are accompanied by different ion species with the same mass‐to‐charge ( m / z ) value. The STJ detector fabricated for this study enables kinetic energy ( E ) measurement of incoming individual ions at a counting rate of up to ∼100 k ions/s and an energy resolution (Δ E / E ) of 15%. Both high counting rate and high‐energy resolution are necessary to independently determine both m and z and not the m / z value only in ion‐counting MS experiments. Ions such as 14 N 2 2+ and 14 N + with the same m / z value can be clearly discriminated using a kinetic‐energy‐sensitive MS. This fine discrimination capability allows direct determination of relative ionization cross‐sections of the homonuclear diatomic ions 14 N 2 2+ / 14 N 2 + and 16 O 2 2+ / 16 O 2 + , which are difficult to measure due to the strong interference by the signals of their dissociated atomic ions with noticeably large ionization cross‐sections. The new instrument requires no low‐abundance heteronuclear diatomic molecules of the forms 14 N 15 N or 16 O 17 O to carry out ionization studies and thus, is expected to be useful in fields such as atmospheric science, interstellar science, or plasma physics. Copyright © 2008 John Wiley & Sons, Ltd.