# US 8,772,708 B2 · Time-of-flight mass spectrometer

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- Number: US 8,772,708 B2
- Document ID: US8772708B2
- Status: Granted
- Kind: B2
- Application number: 13/996,372
- Filed: 2011-12-20
- Published: 2014-02-27
- Granted: 2014-07-08
- Earliest claimed: 2010-12-20
- Assignees: National University Corporation Kobe University; Shimadzu Corporation
- Applicants: Tohru Kinugawa; Osamu Furuhashi
- Inventors: Tohru Kinugawa; Osamu Furuhashi
- Web page: https://patentgrep.com/patent/US8772708B2

## CPC

- H01J 49/405: {characterised by the reflectron, e.g. curved field, electrode shapes}
- G01N 27/62: by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
- H01J 49/403: {characterised by the acceleration optics and/or the extraction fields}
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

An embodiment with a dual-stage reflectron is as follows: (1) On the assumption that a reflector has a base potential XA(U) created by uniform electric fields, its design parameters are adjusted so as to cancel the first and second order derivatives at energy E=E0 of a total time of flight T(E), and a second-order focusing position on a central axis at which the potential value becomes zero is determined (Mamyrin solution). (2) A correcting potential XC(U) to be superposed on XA(U), beginning from the second-order focusing position, is calculated so that T(E) of ions reflected in a region deeper than the second-order focusing position will be constant. (3) Voltage values of the reflector electrodes are determined so that a real potential XR(U)=XA(U)+XC(U) is created on the central axis.

## Claims

### Claim 1

A time-of-flight mass spectrometer including an ion ejector for accelerating target ions by imparting a certain amount of energy to the ions, an ion reflector for reflecting ions ejected from the ion ejector and turning the ions around by an effect of an electric field, an ion detector for detecting the ions reflected by and exiting from the ion reflector, and a reflector driver for driving the ion reflector so as to create a reflecting electric field inside the ion reflector, wherein:
with X denoting a coordinate along a central axis of the ion reflector, the reflector driver applies a voltage to the ion reflector so as to create, inside an inner hollow area of the ion reflector and along the central axis of the ion reflector, a predetermined potential distribution UA(X) in which the potential monotonously changes over the entire ion reflector and therefore an inverse function XA(U) can be uniquely obtained, thus creating an N-th order focusing position at a position with coordinate X0 and potential E0 inside the ion reflector; and
the reflector driver also applies a voltage to the ion reflector within a space having the N-th order focusing position with coordinate X0 as a starting point and extending into a deeper region, so as to superpose, on the predetermined potential XA(U), a predetermined correcting potential XC(U) which can be approximated by a formula proportional to {U(X)−E0}N+3/2 in a vicinity of the coordinate X0 and which is expressed as a smooth function continuing from the coordinate X0 into the deeper region.

### Claim 2 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
a forward ion drift region for making the ions ejected from the ion ejector fly forward is provided between the ion ejector and the ion reflector, the ion reflector subsequently reflects the ions passing through the forward ion drift region and turns the ions around by the effect of the electric field; and
a backward ion drift region for making the ions reflected by and exiting from the ion reflector fly in a direction opposite to the forward ion drift region is provided between the ion reflector and the ion detector.

### Claim 3 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
either the ion ejector and the ion reflector, or the ion reflector and the ion detector, or both are connected to each other with no drift region or similar space provided in between.

### Claim 4 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
the electric field which is to be the predetermined potential distribution XA(U) is a uniform electric field at least in a vicinity of the coordinate X0.

### Claim 5 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
a grid electrode is provided inside an inner hollow area of the ion reflector, the grid electrode dividing the ion reflector into a plurality of stages.

### Claim 6 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
a grid-less structure with no grid electrode provided inside an inner hollow area of the ion reflector is adopted.

### Claim 7 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
the ion reflector is a single-stage system, a first-order focusing position inside the ion reflector is selected as the starting point, and a correcting potential for N=1, which is proportional to {U(X)−E0}2.5, is superposed on a region in a vicinity of a boundary of the starting point.

### Claim 8 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
the ion reflector is a dual-stage system, a second-order focusing position inside the ion reflector is selected as the starting point, and a correcting potential for N=2, which is proportional to {U(X)−E0}3.5, is superposed on a region in a vicinity of a boundary of the starting point.

### Claim 9 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
the ion reflector is a dual-stage system, a first-order focusing position inside the ion reflector is selected as the starting point, and a correcting potential for N=1, which is proportional to {U(X)−E0}2.5, is superposed on a region in a vicinity of a boundary of the starting point.

### Claim 10 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
the ion ejector is an orthogonal acceleration type.

### Claim 11 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
the ion ejector is a MALDI ion source.

### Claim 12 (depends on 2)

The time-of-flight mass spectrometer according to claim 2, wherein:
an accelerating or decelerating region is provided in a portion of the forward ion drift region and/or the backward ion drift region.

### Claim 13 (depends on 2)

The time-of-flight mass spectrometer according to claim 2, wherein:
a focusing lens is provided in a portion of the forward ion drift region.

### Claim 14 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
The ion ejector has a function of a focusing lens.

### Claim 15 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
an aperture or slit for limiting a passing area of the ions is provided between the ion ejector and the ion reflector.

### Claim 16 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
the ion ejector or a portion of electrodes of the ion reflector has the function of limiting a passing area of the ions.

### Claim 17 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
the ion reflector includes a plurality of thin electrodes arranged along an ion beam axis.

### Claim 18 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
the ion reflector includes a resistance element having an electric resistance adjusted along the ion beam axis.

### Claim 19 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, wherein:
the ion reflector is constructed by using a printed circuit board or a microfabricated substrate.

### Claim 20 (depends on 1)

The time-of-flight mass spectrometer according to claim 1, which is designed as a multi-reflection time-of-flight mass spectrometer including a plurality of ion reflectors arranged opposite to each other so that ions are reflected a plurality of times between the plurality of ion reflectors, wherein:
at least one of the plurality of ion reflectors is the aforementioned ion reflector in which a predetermined correcting potential XC(U) is superposed on the predetermined potential XA(U).