US 2021/0341392 A1Published application

Laser ablation analysis

AssigneeApplied Spectra, Inc.

InventorsAlexander A. Bol'shakov, Chunyi Liu, Jong Hyun Yoo, Sudeep J. Pandey, Richard E. Russo, Randolph S. Tribe

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Abstract

Methods for laser induced ablation spectroscopy (LIBS) are disclosed. Light from laser ablation can be gathered into a lightguide fiber bundle that is subdivided into branches. One branch can convey a first portion of the light to a broadband spectrometer operable to analyze a relatively wide spectral segment, and a different branch can convey a second portion of the light to a high dispersion spectrometer operable to measure minor concentrations and/or trace elements. Emissions can be analyzed using a plurality of spectrometers having distinct and/or complementary capabilities, and with a synergistic method using inductively coupled plasma mass spectrometry.

Claims5

Dependent claims

A method for analyzing a composition of a sample using laser ablation spectroscopy, comprising:

placing a sample comprising a multiplicity of distinct sample sites distributed throughout the surface of the sample on a stage operable to move in x and y directions of a plane and in a z direction perpendicular to the plane,
automatically maintaining an optimum height of a first sample site on the sample surface while ablating material with a pulsed laser beam having a preselected spot size in the range of approximately 50 micrometers to 500 micrometers from the first sample site into a first luminous plasma plume;
and automatically maintaining an optimum height of a second sample site while ablating material with a pulsed laser beam having a preselected spot size in the range of approximately 50 micrometers to 500 micrometers from the second sample site into a second luminous plasma plume using a controller operable to automatically adjust a z-coordinate of the sample using a displacement signal proportional to a difference of a z-coordinate of the first sample site relative to a z-coordinate of the second sample site,
waiting a preselected interval of time after the start of each ablation wherein an intensity of spectral features emanating from a molecular species increases during the preselected interval and an intensity spectral features emanating from atomic and/or an ionic species decreases during the interval,
gathering light emanating from each luminous plasma plume after the preselected time interval, and
quantifying an abundance of isotopes of an element at each sample site based on the intensity of the spectral features from molecular species,
wherein the quantifying comprises:
generating a simulated spectrum of the molecular species using a mathematical model,
numerically fitting a combination of simulated spectra to spectral data from the molecular species;
and
determining the abundance of the isotopes of the element at each sample site from the result of the numerical fitting.

8 more elements

A method of determining a sample composition using spectral data comprising wavelength and wavelength intensity values obtained with laser ablation spectroscopy and ion mass to charge peak intensity values obtained with inductively coupled mass spectrometry, the method comprising:

providing a laser pulse from a pulsed laser ablation source;
using the laser pulse to ablate material from a sample site into an emissive plasma plume;
gathering light emanating from the emissive plasma plume into a proximal end of a fiber optic lightguide using collection optics configured to couple the gathered light emanating from the emissive plasma plume into a proximal end of the fiber optic lightguide,
coupling a first portion of the gathered light from a first distal end of the fiber optic lightguide into an optical spectrometer;
receiving spectral data from the optical spectrometer in a computer having instructions operable to determine a representation of the sample site composition based on the data received;
transporting a gaseous portion of ablated material from the plasma plume to an inductively coupled mass spectrometer;
receiving ion mass to charge peak intensity values from the inductively coupled mass spectrometer in the computer;
and
determining a sample site composition depending on combining the wavelength and wavelength intensity values from the first optical spectrometer and normalized values of the ion mass to charge ratio intensities;
wherein the normalization of the ion mass to charge ratio peaks depends correcting the ion mass to charge ratio intensity values for pulse-to-pulse variations in the amount of ablated material based on a signal level from the spectral data.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/366,023Filed 2 Jul 2021
Priority: 5 May 2008
Published: 4 Nov 2021
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

G01N 21/718
Thermally excited: laser microanalysis, i.e. with formation of sample plasma
B23K 26/048
Automatically focusing the laser beam: by controlling the distance between laser head and workpiece
H01J 49/0004
Particle spectrometers or separator tubes: imaging particle spectrometry
H01J 49/0463
For solid samples: desorption by laser or particle beam, followed by ionisation as a separate step

Family

Application61/126,633Us provisional application · filed 5 May 2008
Application12/435,970Continuation in part · filed 5 May 2009
Application61/390,117Us provisional application · filed 5 Oct 2010
Application13/492,923Continuation · filed 10 Jun 2012
Application13/835,582Continuation in part · filed 15 Mar 2013
Application15/201,494Continuation in part · filed 3 Jul 2016
Application15/488,422Continuation · filed 14 Apr 2017
Application16/293,512Continuation in part · filed 5 Mar 2019
Application62/915,653Us provisional application · filed 16 Oct 2019
Application17/073,289Continuation · filed 16 Oct 2020
Application17/366,023Continuation
Application17/073,289Continuation in part
Application16/293,512Continuation
Application15/488,422Continuation in part
Application15/201,494Continuation
Application13/492,923Continuation in part
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US 2021/0341392 A1This patent

From the US filing history. Foreign family members aren’t listed.

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