High resolution mass spectrometry of recoiled ions for isotopic and trace elemental analysis

A method for determining elements on a surface with high pressure mass spectrometry, comprising the steps of:

• pulsing an ion beam of at least about 2 KeV at grazing incidence of between 45.degree. and 80.degree. to impinge said surface;
• and
• detecting the direct recoiled ions of element with a mass spectrometer having a time-of-flight sector comprising at least one linear field free drift tube and at least one toroidal or spherical energy filter with a +/- v polarization to deflect positive or negative ions;
• located at an elevation angle of about 0.degree. to 85.degree. and a channelplate detector for measurement of direct recoiled ions.

A method for quantitive measurement of elements on a surface with a high pressure mass spectrometer comprising the steps of:

• pulsing an ion beam of at least about 2 KeV at grazing incidence to impinge the surface;
• detecting positive or negative ions of elements recoiled from the surface with a first high resolution time-of-flight mass analyzer comprised of at least one linear field free drift tube and at least one toroidal or spherical energy filter with a +/- V polarization on the sectors of the filter to deflect positive or negative ions, wherein the outer sector of said filter contains a hole;
• detecting direct recoiled ions and neutrals with a second mass analyzer attached to the first mass analyzer and positioned to detect ions and neutrals exiting through said hole, wherein said second mass analyzer has a time-of-flight detector located at an elevation angle of 0.degree. to 85.degree., an electrostatic deflection plate to separate negative and positive ions and neutrals, and a channelplate detector with at least three anodes, said anodes detecting either direct recoiled negative or positive ions or neutrals;
• alternately collecting data on the first and second mass analyzers at time intervals ranging from 100 .mu.sec to 1 sec;
• and
• comparing the ion intensity from the first high resolution analyzer to the intensity of the neutrals and ions detected in the second analyzer used to obtain the ion fraction of the recoiled element.

An apparatus for measuring recoiled and direct recoiled ions comprising:

• a sample chamber;
• an ion beam pulsing means for generating a pulsed ion beam, said pulsing means oriented at an angle to the sample chamber, wherein the pulsing ion beam impinges a surface of a sample in the sample chamber at a grazing incidence of about 45.degree. to 80.degree.;
• a first mass analyzer attached to the sample chamber at an elevation angle of about 0.degree. to 85.degree. relative to the sample and in the forward specular direction, said first mass analyzer having at least one field free drift tube and at least one toroidal or spherical energy filter with sector halves polarizable +/- V for the deflection of positive or negative ions and, wherein the outer sector of said filter includes a hole;
• a second mass analyzer for detecting direct recoiled ions and neutrals when the sectors of the first analyzer are grounded, said second analyzer having an electrostatic deflector and an ion detector containing three separate anodes, said ion detector attached to at least one field free drift tube of said first mass analyzer in a position to simultaneously detect ions and neutrals separated by the electrostatic detector, after said ions and neutrals exit through the hole in the outer sector of the first mass analyzer;
• and
• a computer system for regulating the frequency of pulsing and the collection of data from the first and second mass analyzers.

An apparatus for ion scattering spectroscopy and secondary ion mass spectrometry comprising:

• a sample chamber;
• an ion beam pulsing means for generating a pulsed ion beam, said pulsing means oriented at an angle to the sample chamber, wherein the pulsing ion beam impinges a surface of a sample in the sample chamber at a grazing incidence of about 45.degree. to 80.degree.;
• a first mass analyzer for secondary ion mass spectrometry attached to the sample chamber at an angle of about 80.degree. to 180.degree. relative to the sample, said first mass analyzer having at least one toroidal or spherical field free drift tube and at least one toroidal or spherical energy filter with sector halves polarizable +/- V for the deflection of positive or negative ions, and wherein the outer sector of said filter includes a hole;
• a second mass analyzer for ion scattering spectroscopy, said second mass analyzer attached to at least one field free drift tube of said first mass analyzer in a position to detect ions and neutrals, exiting through the hole in the outer sector of the first analyzer;
• and
• a computer system for regulating the frequency of ion pulsing and the collection of data from the first and second mass analyzers.

A device for high pressure real time stoichiometry measurements of a surface comprising:

• a sample chamber;
• an ion beam pulsing means oriented at an angle to the sample chamber generating a pulsed ion beam at a grazing incidence to impinge the surface of a sample in the sample chamber;
• a micro capillary gas doser to form a local area of high pressure on the surface;
• a first array of discrete detectors in the forward specular hemisphere to measure forward ion scatter from the ion beam impinging the surface, said first array including up to about 100 discrete detectors each defining a scattering angle of .+-.0.5.degree.;
• a second array of discrete detectors in the back specular hemisphere to measure the backward ion scatter from the ion beam impinging the surface, said second array including up to about 100 discrete detectors each defining a scattering angle of .+-.0.5.degree.;
• and
• a collection means to collect a multiplicity of time of flight data simultaneously from each detector in both the first and second array of discrete detectors.

A method of measuring elemental surface concentrations in real time comprising the steps of:

• impinging about a 100 .mu.diameter of a surface with a device for high pressure real time stoichiometry measurements, said device comprising a sample chamber, an ion beam pulsing means oriented at an angle to the sample chamber and generating a pulsed ion beam at a grazing incidence to impinge the surface of a sample in the sample chamber and a microcapillary gas doser to form a local area of high pressure on the surface;
• detecting the forward direct recoiled ion and neutral profile from the impinging step with a first array of discrete detectors in the forward specular hemisphere from the ion beam impinging surface, said first array including up to about 100 discrete detectors, each defining a scattering angle of .+-.0.50;
• detecting the low energy ion scattering from the surface with said first array of discrete detectors and with a second array of discrete detectors in the back specular hemisphere, said second array including up to about 100 discrete detectors, each defining in a scattering angle of .+-.0.50;
• sampling the ion scatter at the rate of about every 10 .mu.sec. to 1 sec. with a collection means that collects a multiplicity of time of flight data simultaneously from each detector in both the first and second array of discrete detectors;
• and
• analyzing the data selected from the group of direct recoil scattering, low energy ion scattering and a combination thereof.

A method of determining the crystallography by blocking and shadowing analysis with a device for high pressure time stoichiometry measurements comprising the steps of:

• impinging a surface of a sample with said device, wherein said device comprises a sample chamber, an ion beam pulsing means oriented at an angle to the sample chamber and generating a pulsed ion beam at a grazing incidence to the surface of a sample in the sample chamber and a microcapillary gas doser to form a local area of high pressure on the surface;
• detecting the forward direct recoil ion and neutral profile from the impinging step with a first array of discrete detectors in the forward specular hemisphere, said first array including up to about 100 discrete detectors each defining a scattering angle of .+-.0.50;
• detecting the low energy ion scattering from said surface with a second array of discrete detectors in the back specular hemisphere, said second array including up to about 100 discrete detectors each defining a scattering angle of .+-.0.50;
• collecting the time of flight data simultaneously from each detector in both the first and second array of discrete detectors;
• and
• monitoring the ion beam scattering intensity as a function of scattering angle.

A method for calibrating a DRS or MSRI intensity comprising the steps of:

• inserting into a sample chamber a gas of known composition;
• pulsing an ion beam of at least about 2 KeV into said gas;
• and
• detecting the resultant ionized recoiled atoms of the gas.