Apparatus and method for pulsed mode charge detection mass spectrometry

A charge detection mass spectrometer, comprising:

• an ion source configured to generate ions from a sample,
• an ion trap having a trapping state in which the generated ions received into a ion inlet of the ion trap are stored therein, and a transmission state in which ions stored therein are released from an ion outlet of the ion trap,
• an electrostatic linear ion trap (ELIT) array including at least two ELITs or ELIT regions, each of the at least two ELITs or ELIT regions including first and second ion mirrors and a charge detection cylinder, having a length, positioned therebetween, the first ion mirror of each of the at least two ELITs or ELIT regions defining an ion inlet into the respective one of the at least two ELITs or ELIT regions, each of the at least two ELITs or ELIT regions spaced apart from the ion trap so as to define a respective distance between the ion outlet of the ion trap and an end of the respective charge detection cylinder adjacent to the respective first ion mirror, the first and second ion mirrors of each of the at least two ELITs or ELIT regions having a transmission state in which ions are transmitted therethrough, and a reflection state in which ions entering therein from the charge detection cylinder are reflected back into the charge detection cylinder, and
• processing circuitry configured to control the ion trap from the trapping state to the transmission state thereof for a pulse width duration to cause the ion trap to release at least some of the stored ions from the ion outlet thereof to travel toward the ion inlets of the at least two ELITs or ELIT regions and, for each of the at least two ELITs or ELIT regions, to thereafter control the second and third ion mirrors from the transmission states to the reflection states thereof so as to trap at least one ion in the respective one of the at least two ELITs or ELIT regions,
• wherein a ratio of maximum and minimum values of mass-to-charge ratio of the at least one ion trapped in each of the at least two ELITs or ELIT regions is a function of the distance between the ion outlet of the ion trap and the end of the respective charge detection cylinder adjacent to the respective first ion mirror and the length of the respective charge detection cylinder.

A charge detection mass spectrometer, comprising:

• an ion source configured to generate ions from a sample,
• at least one voltage source configured to produce a plurality of output voltages,
• an ion trap, coupled to a first set of the plurality of output voltages, the ion trap configured to be responsive a trapping state of the first set of the plurality of output voltages to receive the generated ions at an ion inlet thereof and to store the generated ions therein, and to a transmission state of the first set of the plurality of output voltages to release stored ions from an ion outlet thereof,
• an electrostatic linear ion trap (ELIT) array including at least two ELITs or ELIT regions, each of the at least two ELITs or ELIT regions including first and second ion mirrors and a charge detection cylinder, having a length, positioned therebetween, the first ion mirror of each of the at least two ELITs or ELIT regions defining an ion inlet into the respective one of the at least two ELITs or ELIT regions, each of the at least two ELITs or ELIT regions spaced apart from the ion trap so as to define a respective distance between the ion outlet of the ion trap and an end of the respective charge detection cylinder adjacent to the respective first ion mirror, the first and second ion mirrors of each of the at least two ELITs or ELIT regions coupled to second and third sets respectively of the plurality of output voltages, the first and second ion mirrors configured to be responsive to transmission states of the second and third sets of the plurality of output voltages respectively to transmit ions therethrough, and to reflection states of the second and third sets of the plurality of output voltages respectively to reflect ions entering therein from the charge detection cylinder back into the charge detection cylinder, and
• processing circuitry for controlling the first set of voltages from the trapping state to the transmission state thereof for a pulse width duration to cause the ion trap to release at least some of the stored ions from the ion outlet thereof to travel toward the ion inlets of the at least two ELITs or ELIT regions and, for each of the at least two ELITs or ELIT regions, to thereafter:
• (i) control the third set of voltages from the transmission state to the reflection state thereof upon expiration of a first respective delay time from control of the first set of voltages from the trapping state to the transmission state thereof, and (ii) control the second set of voltages from the transmission state to the reflection state thereof upon expiration of a second delay time from control of the third set of the plurality of voltages from the transmission state to the reflection state to trap at least one ion in the respective one of the at least two ELITs or ELIT regions,
• wherein minimum and maximum values of mass-to-charge ratio of the at least one ion trapped in each of the at least two ELITs or ELIT regions is proportional to a sum of the first and second respective delay times,
• and wherein a ratio of the maximum and minimum values of mass-to-charge ratio of the at least one ion trapped in each of the at least two ELITs or ELIT regions is a function of the distance between the ion outlet of the ion trap and the end of the respective charge detection cylinder adjacent to the respective first ion mirror and the length of the respective charge detection cylinder.