Hyperpolarized Noble Gas Surface Probing via Quadrupolar Interactions
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Solution Overview
Problem
Conventional techniques for surface probing, such as optical-based methods and NMR/MRI, are inadequate for porous or optically inaccessible surfaces, particularly due to low signal intensity and inability to distinguish surface signals from bulk material, and existing noble gas isotopes with nuclear electric quadrupole moments face challenges with rapid signal loss and reactivity issues.
Innovation Solution
The use of hyperpolarized and purified noble gas isotopes with nuclear electric quadrupole moments, such as 21Ne, 83Kr, and 131Xe, which are purified from alkali metal vapor to maintain high spin polarization and extend relaxation times, allowing for sensitive surface analysis through quadrupolar interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional NMR/MRI techniques are used for surface probing, then imaging of optically inaccessible surfaces is enabled, but signal intensity is low and surface signals cannot be distinguished from bulk material signals
Solution Approach 1:
The patent applies parameter changes by transitioning from thermal equilibrium polarization to hyperpolarized states of noble gases (such as 3He, 129Xe, 21Ne, 83Kr, 131Xe). This changes the polarization parameter from typical thermal levels to hyperpolarized levels, achieving signal enhancements of many orders of magnitude and enabling detection of surface signals that were previously indistinguishable from bulk material signals
Solution Approach 2:
The patent uses noble gases as intermediary substances to probe surfaces. These gases serve as mediators that can access optically inaccessible surfaces, interact with surface molecules, and return information about surface properties through their hyperpolarized NMR/MRI signals, effectively bridging the gap between the imaging system and the target surface
2Quantity of substance
If hyperpolarized noble gases with nuclear electric quadrupole moments are used for surface probing, then signal enhancement is achieved, but rapid signal loss due to quadrupolar relaxation occurs
Solution Approach 1:
The patent applies preliminary action by pre-polarizing noble gases to hyperpolarized states using optical pumping or dynamic nuclear polarization techniques before introducing them to the surface environment. This preliminary polarization prepares the gas with maximum signal intensity, allowing sufficient time for surface interactions to occur before quadrupolar relaxation causes signal loss
Solution Approach 2:
The patent employs the skipping principle by rapidly introducing hyperpolarized noble gases to surfaces and quickly acquiring NMR/MRI signals before quadrupolar relaxation can significantly degrade the signal. This rushed-through approach minimizes the time window during which signal loss occurs, capturing useful surface information before relaxation effects dominate
3Quantity of substance
If alkali metal vapor is used for spin exchange optical pumping of noble gases, then high spin polarization is obtained, but reactivity issues and signal loss occur
Solution Approach 1:
The patent applies the taking out principle by removing alkali metal vapor from the system after it has served its purpose in spin exchange optical pumping. By extracting the harmful alkali metal component while retaining the beneficial hyperpolarized noble gas, the system achieves high spin polarization without the subsequent reactivity issues and signal loss that would occur if alkali metal vapor remained present during surface probing
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
Enables robust and sensitive surface probing with improved signal intensity and prolonged relaxation times, facilitating detailed analysis of reactive and porous surfaces without adverse biological impact or surface alteration.
Implementation Method 1
hyperpolarized gases having a nuclear electric quadrupole moment... The use of hyperpolarized and purified noble gas isotopes with nuclear electric quadrupole moments... allowing for sensitive surface analysis through quadrupolar interactions
Implementation Method 2
hyperpolarized and purified noble gas isotopes... purified from alkali metal vapor to maintain high spin polarization and extend relaxation times
Data Source
AI summary
Methods and related devices are provided for probing a surface by application of a hyperpolarized noble gas having a nuclear electric quadrupole moment to the surface. In an embodiment, the hyperpolarized noble gas is substantially free of alkali metal vapor, such as rubidium vapor used to hyperpolarize the noble gas. Noble gas interaction with the surface of interest is detected by measuring quadrupolar-driven events such as T1, T2 relaxation or coherent processes by nuclear magnetic resonance spectroscopy or by magnetic resonance imaging, for example. The method is capable of probing a variety of surfaces that are difficult to analyze by conventional methods, including biological or non-biological surfaces, to obtain detailed and reliable information related to surface chemical composition.