Method of and apparatus for nuclear quadrupole resonance testing a sample, and pulse sequence for exciting nuclear quadrupole resonance

Apparatus for nuclear quadrupole resonance testing a sample which has a first type substance containing quadrupolar nuclei and a second type substance which may give rise to spurious signals which interfere with response signals from the quadrupolar nuclei, comprising:

• means for applying a pulse sequence to the sample to excite nuclear quadrupole resonance, the pulse sequence comprising a plurality of pairs of pulses, each of said plurality of pairs of pulses comprising two member pulses;
• means for detecting for each of said plurality of pairs of pulses, respective response signals following the two member pulses of the pair;
• and
• means for comparing, for each of said plurality of pairs of pulses, said respective response signals following the two member pulses of the pair;
• the pulse sequence being such that respective spurious signals following the two member pulses of each of said plurality of pairs of pulses can be at least partially cancelled by the comparison without the corresponding true quadrupole resonance signals being completely cancelled;
• and
• for each of said plurality of pairs of pulses, the two member pulses being of like phase.

A method of nuclear quadrupole resonance testing a sample containing quadrupolar nuclei, which sample may give rise to spurious signals which interfere with response signals from the quadrupolar nuclei, comprising:

• applying a pulse sequence to the sample to excite nuclear quadrupole resonance, the pulse sequence comprising a plurality of pairs of pulses, each of said plurality of pairs of pulses comprising two member pulses;
• detecting, for each of said plurality of pairs of pulses, respective response signals following the two member pulses of the pair;
• and
• comparing, for each of said plurality of pairs of pulses, said respective response signals following the two member pulses of the pair;
• the pulse sequence being such that respective spurious signals following the two member pulses of each of said plurality of pairs of pulses can be at least partially cancelled by the comparison without the corresponding true quadrupole resonance signals being completely cancelled;
• and
• for each of said plurality of pairs of pulses, the two member pulses being of like phase;
• wherein the member pulses of at least one of said plurality of pairs have different phases from the member pulses of at least one other of said plurality of pairs.

Apparatus for nuclear quadrupole resonance testing a sample comprising a first type substance containing quadrupolar nuclei and a second type substance which may give rise to spurious signals which interfere with response signals from the quadrupolar nuclei, comprising:

• means for applying a pulse sequence to the sample to excite nuclear quadrupole resonance, the pulse sequence comprising a plurality of pairs of pulses, each of said plurality of pairs of pulses comprising two member pulses;
• means for detecting for each of said plurality of pairs of pulses, respective response signals following the two member pulses of the pair;
• and
• means for comparing, for each of said plurality of pairs of pulses, said respective response signals following the two member pulses of the pair;
• the pulse sequence being such that respective spurious signals following the two member pulses of each of said plurality of pairs of pulses can be at least partially cancelled by the comparison without the corresponding true quadrupole resonance signals being completely cancelled;
• and
• for each of said plurality of pairs of pulses, the two member pulses being of like phase;
• wherein the member pulses of at least one of said plurality of pairs have different phases from the member pulses of at least one other of said plurality of pairs.

A pulse sequence for exciting nuclear quadrupole resonance in a sample having a first type substance containing quadrupolar nuclei and a second type substance which may give rise to spurious signals which interfere with response signals from the quadrupolar nuclei, the pulse sequence comprising:

• a plurality of pairs of pulses,
• each of said plurality of pairs of pulses comprising two member pulses,
• the pulse sequence being such that respective spurious signals following the two member pulses of each of said plurality of pairs of pulses can be at least partially cancelled without the corresponding true quadrupole resonance signals being completely cancelled, and,
• for each of said plurality of pairs of pulses, the two member pulses being of like phase,
• wherein the member pulses of at least one of said plurality of pairs have a different phase from the member pulses of at least one other of said plurality of pairs.