METHOD FOR ANALYZING IONIC STRUCTURE

摘要

A method for analyzing ionic structure, including: applying a radio frequency electric field on an ion mass analyzer to cause sample ions to be excited to a motion amplitude, the motion amplitude at this moment being recorded as a primary motion amplitude; continuously feeding carrier gas into the ion mass analyzer and keeping a certain degree of vacuum in the ion mass analyzer, the sample ions being collided with the carrier gas and the motion amplitude being decreased gradually, and collecting a time domain signal of an image current generated by the sample ions during the process; and analyzing the time domain signal through a time-frequency analysis method and obtaining time-varying characteristic curves indicating corresponding relations between the motion frequencies of the ions having corresponding sizes and the collision cross sectional areas of the ions and the carrier gas, thus distinguishing among ions having different sizes.

主权项

1. A method for analyzing ionic structure, comprising the following steps of:
ion trapping and exciting step: applying a radio frequency electric field on an ion mass analyzer to trap sample ions in the ion mass analyzer, the applied radio frequency electric field having a high order component; and applying an an auxiliary alternating current electric field or applying a broadband excitation electric field on the ion mass analyzer to cause the sample ions to be excited to a motion amplitude not exceeding the trapping ability of the ion mass analyzer, the motion amplitude at this moment being recorded as a primary motion amplitude (a0) and the moment corresponding to the primary motion amplitude (a0) being recorded as a first moment (t0); signal collecting step: continuously feeding carrier gas into the ion mass analyzer and keeping a degree of vacuum in the ion mass analyzer to be smaller than 1.333 Pa, the sample ions being collided with the carrier gas and the motion amplitude being decreased gradually till a second moment (tt), and collecting a time domain signal of an image current generated by the sample ions during the process from the first moment (t0) to the second moment (tt); and signal processing step: analyzing the time domain signal through a time-frequency analysis method and respectively obtaining time-varying characteristic curves (C) of the motion frequencies (f) of ions having various sizes in the sample ions varied with time so as to distinguish among the ions having different sizes, each of the time-varying characteristic curves (C) indicating a corresponding relation between a motion frequency of the ion having a corresponding size and a collision cross sectional area of the ion and the carrier gas.