Patent ID: 8153084

Claim:
A sample tube for holding a liquid NMR sample substance in an NMR probe head, the sample tube extending along a z axis and having an internal cavity that extends axially in a direction of the z axis, said internal cavity being open at an axially upper end thereof, and closed at an axially lower end thereof, wherein a cross-sectional surface of said cavity, which extends perpendicularly to the z axis and is parallel to an xy coordinate plane, has an elongated shape in a direction of an x axis and has maximum dimensions a in the y direction and b in the x direction, wherein a<b, a cross-section of an outer surface of the sample tube, which extends perpendicularly to the z axis and parallel to the xy coordinate plane having a circular shape, wherein said cavity has said elongated shape along the x axis only over a partial section L z which is smaller than an overall length L of the sample tube, wherein said cavity has a circular cross-sectional surface and contains two precision shells of length L z which are connected to an inner wall of the cavity and are preferentially positioned exactly diametrally opposite to each other, wherein each of the two precision shells has a shape which is defined along the length L z by two surfaces subtending a periphery, namely a first cylindrical surface which preferentially has exactly the same curvature as an inner wall of the sample tube, and a second surface which is completely flat and extends parallel to an axis of said cylindrical surface, wherein two flat surfaces of said two precision shells are parallel to each other and define an approximately rectangular cavity in which the sample substance is completely or partially filled, wherein lower ends of said two precision shells are solidly connected to a round disk to prevent sample substance from entering into a space below said disk.