Tandem time-of-flight mass spectrometer

A time-of-flight mass spectrometer, comprising:

• an ion source;
• a velocity selector downstream of the ion source;
• a dissociation cell downstream of the velocity selector;
• a pulsed, linear ion accelerator downstream of the dissociation cell;
• a reflectron downstream of the pulsed, linear ion accelerator;
• and
• an ion detector for detecting ions reflected by the reflectron.

A time-of-flight mass spectrometer, comprising:

• an ion source that focuses ions at a first space focal plane;
• a velocity selector downstream of the ion source, the velocity selector having an entry located at the first space focal plane;
• a dissociation cell downstream of the velocity selector;
• an ion accelerator downstream of the dissociation cell, the accelerator including plural electrodes, each electrode initially at instrument ground potential, each of the electrodes defining an aperture, and the apertures defining a linear flight path through the accelerator, the accelerator focusing ions at a second space focal plane;
• a reflectron downstream of the ion accelerator, the reflectron defining an object plane located at the second space focal plane, the reflectron focusing ions at a third space focal plane;
• and
• an ion detector located at the third space focal plane.

A mass spectrometer, comprising:

• an ion source;
• a velocity selector downstream of the ion source, the velocity selector comprising a first ion deflector including a plurality of electrically conductive strips defining a plurality of channels, the strips including alternate positive voltage strips connected to a first positive voltage source, and alternate negative voltage strips connected to a first negative voltage source, and a second ion deflector in series with the first ion deflector, the second ion deflector including a plurality of electrically conductive strips defining a plurality of channels, the strips including alternate positive voltage strips connected to a second positive voltage source, and alternate negative voltage strips connected to a second negative voltage source;
• a dissociation cell downstream of the velocity selector;
• a reflectron downstream of the dissociation cell;
• and
• a first ion detector positioned to detect ions reflected by the reflectron.

A mass spectrometer, comprising:

• an ion source for focusing ions at a first space focal plane;
• a velocity selector downstream of the ion source, the velocity selector having an entry located at the first space focal plane, the velocity selector including a first ion deflector including a plurality of electrically conductive strips defining a plurality of channels, the strips including alternate positive voltage strips connected to a first positive voltage source, and alternate negative voltage strips connected to a first negative voltage source, and a second ion deflector in series with the first ion deflector, the second ion deflector including a plurality of electrically conductive strips defining a plurality of channels, the strips including alternate positive voltage strips connected to a second positive voltage source, and alternate negative voltage strips connected to a second negative voltage source;
• a dissociation cell downstream of the velocity selector;
• an ion accelerator downstream of the dissociation cell, the accelerator including plural electrodes, each electrode initially at instrument ground potential, each of the electrodes defining a aperture, and the apertures defining a flight path through the accelerator, the accelerator focusing ions at a second space focal plane;
• a reflectron downstream of the ion accelerator, the reflectron defining an object plane located at the second space focal plane, the reflectron focusing ions at a third space focal plane;
• and
• an ion detector located at the third space focal plane.

A method for producing a mass spectrum, comprising:

• ionizing a material to produce a set of ions that is confined to a sufficiently small volume of space and to a sufficiently short interval of time to allow subsequent space focusing of the set of ions;
• accelerating the set of ions so that each ion's velocity within the set of ions depends on the mass of the ion;
• allowing the set of ions to drift along a flight path of a time-of-flight mass analyzer so that ions within the set of ions having different velocities spatially separate along the flight path;
• deflecting all but a select subset of the ions from the flight path, the subset of ions having a select velocity range;
• inducing dissociation of a portion of the subset of ions;
• accelerating the subset of ions linearly along the flight path so that the velocity of each ion within the subset of ions depends on the mass of the ion;
• allowing the subset of ions to drift along the flight path so that ions of different velocities spatially separate along the flight path;
• and
• detecting the subset of ions at a location along the flight path.

A method for producing a mass spectrum, comprising:

• ionizing a material to produce a set of ions that is confined to a sufficiently small volume of space and to a sufficiently short internal of time to allow for subsequent space focusing of the set of ions;
• accelerating the set of ions such that the velocity of each ion within the set of ions depends on the mass of the ion;
• allowing the set of ions to move along a flight path of a time-of-flight mass analyzer so that ions of different velocities spatially separate along the flight path;
• applying a voltage across a first ion deflector positioned along the flight path to deflect ions passing through the first ion deflector in a first direction away from the flight path;
• switching off the voltage applied to the first ion deflector in phase with passage of a subset of ions having a select range of velocities so that the subset of ions is deflected less in the first direction than preceding ions;
• switching on a voltage applied to a second ion deflector, arranged downstream of the first ion deflector, in phase with passage of the subset of ions to deflect ions passing through the second ion deflector in a second direction to deflect the subset of ions back along the flight path, and to deflect ions following the subset of ions away from the flight path;
• maintaining the voltage applied to the second ion deflector to deflect ions following the subset of ions away from the flight path;
• inducing dissociation of a portion of the subset of ions;
• accelerating the subset of ions, such that each ion's velocity within the subset of ions depends on the mass of the ion;
• focusing the subset of ions at a space focal plane;
• and
• detecting ions at the space focal plane.

A method for selecting a subset of ions from a set of ions, comprising:

• applying a voltage across a first ion deflector positioned along a flight path of a time-of-flight mass analyzer so as to deflect ions passing through the first ion deflector in a first direction away from the flight path;
• switching off the voltage applied to the first ion deflector in phase with the passage of a subset of ions having a select range of velocities so that the subset of ions is deflected less in the first direction than preceding ions;
• switching on a voltage applied to a second ion deflector arranged downstream of the first ion deflector in phase with passage of the subset of ions to deflect ions passing through the second ion deflector in a second direction and to deflect the subset of ions back along the flight path;
• and
• maintaining a voltage across the second ion deflector to deflect ions following the subset of ions away from the flight path.

A method for selecting a subset of ions from a set of ions, comprising:

• accelerating a set of ions such that the ions have varying velocities;
• allowing the set of ions to move along a flight path of a time-of-flight mass analyzer so that ions of different velocities spatially separate along the flight path;
• applying a voltage across a first ion deflector positioned along the flight path so as to deflect ions passing through the first ion deflector in a first direction away from the flight path;
• switching off the voltage across the first ion deflector in phase with passage of a subset of ions having a select range of velocities so that the subset of ions is deflected less in the first direction than preceding ions;
• switching on the voltage across a second ion deflector arranged downstream of the first ion deflector in phase with the passage of the subset of ions to deflect ions passing through the second ion deflector in a second direction and to deflect the subset of ions back along the flight path;
• and
• maintaining a voltage across the second ion deflector to deflect ions following the subset of ions away from the flight path.

A method for producing a mass spectrum, comprising:

• ionizing a material to produce a pulsed or continuous beam of ions that has a velocity in a first direction and a width in a second direction orthogonal to the first direction;
• injecting the beam of ions in the first direction into an extraction region of a two-stage ion extraction source;
• accelerating a set of ions that is confined to a short interval of time out of the beam in the second direction orthogonal to the first direction so that each ion's velocity within the set of ions depends on the mass of the ion;
• allowing the set of ions to drift along a flight path of a time-of-flight mass analyzer so that ions within the set of ions having different velocities spatially separate along the flight path;
• deflecting all of the set of ions, except a select subset of the ions, from the flight path, the select subset of ions having a select velocity range;
• inducing dissociation of a portion of the subset of ions;
• accelerating the subset of ions linearly along the flight path so that each ion's velocity within the subset of ions depends on the mass of the ion;
• allowing the subset of ions to drift along the flight path so that ions having different velocities spatially separate along the flight path;
• and
• detecting the subset of ions at a location along the flight path.

A method for producing a mass spectrum, comprising:

• ionizing a material to produce a pulsed or continuous beam of ions that has a velocity in a first direction and a width in a second direction orthogonal to the first direction;
• injecting the beam of ions in the first direction into an extraction region of a two-stage ion extraction source;
• accelerating a select set of ions that is confined to a short interval of time out of the beam in the second direction orthogonal to the first direction such that each ion's velocity within the set of ions depends on the mass of the ion;
• allowing the set of ions to move along a flight path of a time-of-flight mass analyzer so that ions of different velocities spatially separate along the flight path;
• applying a voltage across a first ion deflector positioned along the flight path to deflect ions passing through the first ion deflector in a first direction away from the flight path;
• switching off the voltage applied to the first ion deflector in phase with the passage of a subset of ions having a select range of velocities so that the subset of ions is deflected less in the first direction than preceding ions;
• switching on a voltage applied to a second ion deflector arranged downstream the first ion deflector in phase with passage of the subset of ions so as to deflect ions passing through the second ion deflector in a second direction to deflect the subset of ions back along the flight path, and to deflect ions following the subset of ions away from the flight path;
• maintaining the voltage applied to the second ion deflector so as to deflect ions following the subset of ions away from the flight path;
• inducing dissociation of a portion of the subset of ions;
• accelerating the subset of ions, such that the each ion's velocity within the subset of ions depends on the mass of the ion;
• focusing the subset of ions at a space focal plane;
• and detecting ions at the space focal plane.