-- Bruker-500, A1: cryo-1H optimized, Excellent for 1D 1H experiments, such as acquiring 1D 1H NMR data;
optimum for 1H detected experiments, such as 2D's 1H-13C(X): HMQC(HSQC), HMBC, etc.
-- Bruker-500, A2: cryo-13C optimized, excellent for 1D 13C experiments.
-- Bruker-500, A3: cryo-QNP optimized, excellent for 1D 1H,13C,31P, and 15N direct detection experiments.
All spectrometers use dry nitrogen gas for routine operation.