US 5,962,849 A · Particle selection method and a time-of flight mass spectrometer

Abstract

In the time-of-flight mass spectrometer, the mass spectrometer with high resolution is provided which defines the initial position and the initial velocity of the charged particles and selects only the stable charged particles to measure. First, all of the charged particles Pe are accelerated to one direction in a homogeneous or spatially uniform electric field during a common finite period of time, and then all of the charged particles Pe are accelerated to the opposite direction of the former in a homogeneous or spatially uniform electric field during a common finite period of time and given the same momentum in the opposite direction of the former. Two kind of particle selection method can be adopted. Only the charged particles Pe passing through a predetermined position at a predetermined time are selected by the selector. The charged particles Pe passing through the selector are defected by the first and second deflectors and then only the charged particles passing through a predetermined point of the slit are selected and reach the ion detector. Finally, the mass spectrum is obtained by measuring the time-of-flight of the particles using the ion detector.

Claims9

Dependent claims

A particle selection method comprising the steps of:

applying alternating positive and negative voltages to effect double pulsing of a plurality of charged particles during a common finite period of time, whereby said charged particles are accelerated in first one direction by a homogeneous or spatially uniform electric field during said common finite period of time, which does not exceed that period of time defined by when the accelerated particles escape from the uniform electric field, and then accelerating said plurality of ionized charged particles to an opposite direction of said one direction by said homogeneous or spatially uniform electric field during said common finite period of time, so that the same momentum is provided to all of said plurality of charged particles;
and
passing only the charged particles having the same initial condition through the same position at the same time after the completion of said acceleration.

A time-of-flight mass spectrometer comprising:

a double pulsed accelerator for applying alternating positive and negative voltages to effect double pulsing of a plurality of charged particles during a common finite period of time, whereby said charged particles are accelerated in first one direction by a homogeneous or spatially uniform electric field during said common finite period of time, which does not exceed that period of time defined by when the accelerated particles escape from the uniform electric field, and then accelerating said plurality of ionized charged particles to an opposite direction of said one direction by said homogeneous or spatially uniform electric field during said common finite period of time, so that the same momentum is provided to all of said plurality of charged particles;
a selector arranged at a special focus defined in relation to a particular position where, by the double pulsed acceleration of said double pulsed accelerator, said charged particles having a same initial condition pass through at a same time independent of the mass or charge of said charged particles;
a first deflector and a second deflector for deflecting stable particles of said plurality of charged particles passed through said selector;
a slit for selectively passing an output from said second deflector which is comprised only of those stable particles having no change of mass or charge state and particles which ha a specific change of charge-to-mass ratio;
and
an ion detector for measuring time-of-flight of said charged particles from said slit.

3 more elements

Dependencies are inferred from the claim text.

Particle selection method and a time-of flight mass spectrometer

Life of this patent

Particle selection method and a time-of flight mass spectrometer

Life of this patent

Abstract

Claims9