Temperature Compensated NMR Magnetic Field Probes

A magnetic field probe, particularly for magnetic resonance applications, comprising:

• a detector liquid that exhibits a nuclear magnetic resonance (NMR) line characterized by a chemical shift δ;
• an electrically conductive structure surrounding a detection region of the detector liquid for receiving therefrom a magnetic resonance signal;
• and
• a container containing the detector liquid;
• the detector liquid containing paramagnetic dopant means dissolved therein;
• said NMR transition having an observable resonance frequency ω when the field probe is placed in an external magnetic field;
• the field probe having orientation means for orienting the field probe in relation to a reference direction of said external magnetic field;
• characterized in that the concentration cD of said paramagnetic dopant means is selected in such manner that, when the field probe is placed into an external magnetic field B0 and oriented in a predefined manner with respect to said external magnetic field at a given temperature T0, a temperature dependence ω′(T0) of said resonance frequency ω defined as
• ω
• ′
• 
• (
• T
• 0
• )
• :=
• ∂
• ω
• ∂
• T
• 
• (
• T
• 0
• )
• =
• γ
• 
• 
• B
• 0
• 
• (
• Σ
• i
• 
• n
• i
• 
• χ
• i
• ′
• 
• (
• T
• 0
• )
• +
• D
• d
• 
• χ
• d
• ′
• 
• (
• T
• 0
• )
• +
• δ
• ′
• 
• (
• T
• 0
• )
• )
• (
• 1
• )
• wherein:
• γ is the gyromagnetic ratio of the nucleus giving rise to said NMR line;
• i denotes any magnetized component of the probe, excluding the detector liquid;
• ni is the relative field factor of the microscopic magnetic field at the position of the detection region produced by the magnetized component i;
• χi′(T0) is the temperature dependence of the volume susceptibility of component i at temperature T0;
• Dd is the relative field factor of the microscopic magnetic field at the position of the detection region produced by the magnetized detector liquid;
• χd′(T0) is the total temperature dependence of the volume susceptibility of the detector liquid including dopant means at temperature T0;
• and
• δ′(T0) is the temperature dependence of the total chemical shift of the nuclear magnetic resonance under study
• is substantially zero.