Laser Ablation Plasma Temperature Normalization

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Solution Overview

Problem

The LIBS method faces challenges in accurately determining the concentration of elements due to variations in plasma temperature and ablated mass, leading to uncertainties in measurements, especially when experimental conditions differ from those used in calibration.

Innovation Solution

The method uses the ratio of intensities of two emission lines from a tracer element to characterize plasma temperature, allowing for calibration measurements to be adjusted by varying the acquisition delay, thereby normalizing the measurements to match the temperature conditions of the calibration, and uses this ratio to determine the concentration of the element being analyzed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If calibration measurements are performed under fixed conditions, then the calibration curves can be established, but the measurements become inaccurate when experimental conditions (temperature, ablated mass) differ from calibration conditions

Engineering Contradiction:

Improveconcentration determination accuracyVSAvoidadaptability to varying experimental conditions

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The invention changes the parameter used for calibration from fixed intensity values to intensity ratios that are representative of plasma temperature. By using the ratio of intensities of two emission lines from a tracer element, the calibration becomes adaptable to different plasma temperatures without requiring recalibration under each specific condition. This resolves the contradiction by making the measurement system both precise and adaptable through parameter transformation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention introduces an intermediary parameter (intensity ratio representative of plasma temperature) that mediates between the calibration measurements and the actual measurements under varying conditions. This intermediary allows the system to account for temperature variations and ablated mass differences, enabling accurate concentration determination across different experimental conditions without requiring separate calibration curves for each condition.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the plasma temperature varies between calibration and measurement, then the intensity of emission lines changes, but the concentration determination becomes uncertain

Engineering Contradiction:

Improveconcentration measurement accuracyVSAvoidplasma temperature stability

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

The invention transforms the temperature-sensitive intensity parameter into a temperature-independent intensity ratio parameter. By using the ratio of two emission line intensities from the same tracer element, the temperature dependence is normalized, allowing measurements to be compared with calibration data regardless of plasma temperature variations. This eliminates the need for stable plasma temperature while maintaining measurement precision.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If the amount of ablated material varies, then the total emission intensity changes, but the concentration calculation becomes unreliable

Engineering Contradiction:

Improveconcentration determination reliabilityVSAvoidablated mass consistency

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The invention changes from using absolute intensity values (which depend on ablated mass) to using intensity ratios (which are independent of ablated mass). The ratio of intensities of two emission lines from a tracer element remains constant regardless of the total amount of material ablated, allowing reliable concentration determination even when the ablated mass varies between measurements and calibration.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces measurement uncertainties by ensuring that experimental measurements are compared under similar temperature conditions, improving the accuracy of concentration determination and allowing for analysis of materials with varying physicochemical properties without the need for extensive recalibration.

Implementation Method 1

when it is subjected to ablation by a laser pulse

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

ablation by a laser pulse

Methodology Applied

Scientific EffectAblation: Ablation

Implementation Method 3

uses the ratio of intensities of two emission lines from a tracer element present in the plasma generated by the laser beam

Methodology Applied

Scientific EffectAtomic emission: Luminescence

Data Source

PatentUS7944558B2Method and system for physicochemical analysis using a laser pulsed ablation

Publication Date: 2011.05.17 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A method for physicochemical analysis of a material during its ablation with a pulsed laser. The method uses the ratio of intensity levels of two emission lines of a tracer element derived from plasma generated by the laser beam to characterize the plasma excitation temperature. The method determines concentration of an element to be measured in the plasma using standard measurements indicating correspondence between a concentration of the element to measured and a variation of intensity of an emission line and different ratios between intensity levels of two emission lines of the tracer element, the ratios representing the plasma temperature.