| abstract |
While applying a square wave voltage to the ion electrode ( 21 ) so that ions already captured in the ion trap ( 20 ) do not disperse, the frequency of the square wave voltage is temporarily increased at the timing when the ions generated in response to the short time irradiation of a laser light reach the ion inlet ( 25 ). This decreases the Mathieu parameter q z , and the potential well becomes shallow, which makes it easy for ions to enter the ion trap ( 20 ). Although the ions that have been already captured become more likely to disperse, the frequency of the square wave voltage is decreased before they deviate from the stable orbit. Thus, the dispersion of the ions can also be avoided. Accordingly, while the number of captured ions is not decreased, new ions are further added, and thereby the amount of ions can be increased. By performing a mass separation and detection after that, the signal intensity in one mass analysis can be increased. Thereby, the number of repetition of the mass analysis for summing up the mass profiles can be decreased, and the signal intensity can be increased while decreasing the measuring time. |