12360 IUPAC Gold Book - collisional focusing 10.1351/goldbook.12360 12360 current 1 Effect where collisions with a buffer gas in a radio-frequency ion trap or transmission quadrupole causes ions to lose translational energy and concentrate at the center of the trap or axis of the linear quadrupole. The effect increases with gas pressure up to a point where ion scattering becomes the dominant process. buffer gas https://goldbook.iupac.org//terms/view/12350 ion trap https://goldbook.iupac.org//terms/view/12447 transmission quadrupole https://goldbook.iupac.org//terms/view/12602 PAC, 2013, 85, 1515. 'Definitions of terms relating to mass spectrometry (IUPAC Recommendations 2013)' on page 1531 (https://doi.org/10.1351/PAC-REC-06-04-06) https://goldbook.iupac.org/terms/view/12360/html https://goldbook.iupac.org/terms/view/12360/json https://goldbook.iupac.org/terms/view/12360/plain Citation: 'collisional focusing' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.12360 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-06-20T03:44:43+00:00