VUV Transmission Window Nanolayer Stack Hydrocarbon Protection

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Solution Overview

Problem

VUV gas discharge lamps suffer from short operational lifetimes and reduced transmission efficiency due to hydrocarbon contamination and incompatibility issues with hygroscopic lithium fluoride crystals, particularly in high-humidity environments and when exposed to volatile organic compounds.

Innovation Solution

A VUV-transparent transmission window with a nanolayer stack, including a conducting and inert top layer such as gold, is used to reduce hydrocarbon attachment and enhance bonding, thereby prolonging operational lifetime and maintaining transmission efficiency. The nanolayer stack can be directly deposited on substrates like MgF2 or LiF crystals, with optional bonding layers for improved adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If lithium fluoride crystals are used as VUV transmission windows, then transmission efficiency below 110 nm is improved, but operational lifetime is reduced due to hygroscopic properties and short circuiting in humid environments

Engineering Contradiction:

ImproveVUV transmission efficiencyVSAvoidoperational lifetime

Core Design Contradiction:

Illumination intensityVSDuration of action of moving object

Solution Approach 1:

A hydrophobic coating layer is applied to the LiF crystal surface to act as an intermediary barrier that prevents water vapor from reaching and short-circuiting the piezoelectric transducer, thereby maintaining both high transmission efficiency and extended operational lifetime in humid environments

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The transmission window system combines LiF crystal with a hydrophobic coating material to create a composite structure that leverages the excellent VUV transmission properties of LiF while adding the moisture-repellent characteristics of the coating to prevent hygroscopic degradation

Inventive Principle:

Principle #40Composite materials

2Measurement precision

If VUV lamps are exposed to volatile organic compounds, then detection capability is improved, but hydrocarbon contamination on the window increases, reducing transmission efficiency

Engineering Contradiction:

Improvedetection capabilityVSAvoidtransmission efficiency

Core Design Contradiction:

Measurement precisionVSIllumination intensity

Solution Approach 1:

The hydrophobic coating serves as a mediator between the VUV lamp window and volatile organic compounds, creating a surface that minimizes hydrocarbon adsorption and contamination, thereby maintaining transmission efficiency while allowing detection of VOCs

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The hydrophobic coating converts the potentially harmful effect of hydrocarbon contamination into a beneficial low-adsorption surface that actively repels organic compounds, turning the challenge of VOC detection into an opportunity to maintain clean window surfaces

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Strength

If MgF2 is used as transmission window material, then chemical resistance and mechanical strength are improved, but transmission efficiency below 110 nm is reduced compared to LiF

Engineering Contradiction:

Improvemechanical strength and chemical resistanceVSAvoidtransmission efficiency below 110 nm

Core Design Contradiction:

StrengthVSIllumination intensity

Solution Approach 1:

The invention changes the surface properties of the MgF2 window by applying a hydrophobic coating, which modifies the optical and chemical parameters of the surface to reduce hydrocarbon adsorption while maintaining the bulk mechanical and chemical resistance properties of MgF2

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

The solution significantly prolongs the operational lifetime of VUV lamps by minimizing hydrocarbon contamination and maintaining high transmission efficiency, even in challenging environments, while allowing for a smaller sample ionization volume and enhanced detection capabilities in photo-ionization detectors.

Implementation Method 1

hydrocarbon contamination

Methodology Applied

Scientific EffectHydrocarbon attachment: Adsorption

Implementation Method 2

VUV-transparent substrate

Methodology Applied

Scientific EffectVUV light transmission: Absorption (EM radiation)

Implementation Method 3

low-pressure gas discharge lamp that, depending on the gas fill, typically emits intense light between 105 nm (11.8 eV) and 150 nm (8.4 eV)

Methodology Applied

Scientific EffectGas discharge: Electric Glow Discharge

Implementation Method 4

Atmospheric Pressure Photo-ionization (APPI) is a well-known soft ionization mechanism, which induces the formation of electron-ion pairs from molecules upon the absorption of high energy photons

Methodology Applied

Scientific EffectPhoto-ionization: Photoionisation

Data Source

PatentUS10290487B2Transmission window for a vacuum ultraviolet gas discharge lamp

Publication Date: 2019.05.14 INL INT IBERIAN NANOTECHNOLOGY LAB

AI summary

A transmission window (1) for a VUV gas discharge lamp is defined which comprises a substrate (3) which is transparent to the VUV spectrum and a nanolayer stack (2) provided on the substrate, the nanolayer stack (2) comprising at least one nanolayer and the top layer of the nanolayer stack being electrically conducting. Also, a VUV gas discharge lamp, a photo-ionization device and a photo-ionization detector comprising said transmission window are defined.