Journal: Journal of magnetic resonance (San Diego, Calif. : 1997)

Article Title: Proton-detected Separated Local Field Spectroscopy

doi: 10.1016/j.jmr.2007.10.002

Figure Lengend Snippet: Timing diagrams for pulse sequences (left column) and the corresponding two-dimensional SLF spectra of a single-crystal of a model peptide (right column). A. and B. 15N-detected PISEMA. C. and D. 15N-detected PISEMO. E. and F. 1H-detected PISEMO. CW refers to continuous wave irradiation. SPINAL-16 refers to modulated irradiation (34, 35). The sample is a single crystal of 13Cα, 15N labeled N-acetyl-leucine at an arbitrary orientation. The probe is a triple-tuned 1H, 13C, 15N homebuilt probe with a single 5mm ID solenoid coil. The Bruker Avance II console was interfaced with a Chemagnetics 500 MHz power amplifier and a homebuilt transmit/receive switch built with crossed diodes and a λ/4 coaxial cable for 1H detection. For 15N detection, we use the preamplifier module supplied by Bruker. In all experiments, the measured B1 was 55.6 kHz for all three channels (1H, 13C, and 15N). This corresponds to a 90° pulse of 4.5 µs and 5.8 µs for 116° pulse. For the data shown in Figure 1B, the cycle time is 29.2 µs and the jump frequency is +/− 39544.5 Hz. For the data shown in Figure 1D and E, the cycle time is 34.8 µs, which is 6 times the duration of the 116° pulse. The scaling factor for PISEMA is 0.82. The corresponding scaling factor for PISEMO was determined to be 0.67. For 1H-detected PISEMO, 16 scans, 256 t1 are acquired with dwell time of 40 µs and 34.8 µs in t1 and t2 dimension respectively. For 15N-detected PISEMA and PISEMO experiments, 32 scans, 256 t1 are acquired. The dwell times for PISEMA are 29.2 µs and 40 µs in t1 and t2 dimension. For PISEMO experiment, the dwell times are 34.8 µs and 40 µs in t1 and t2 dimension. The number of scans in 15N-detected PISEMO is twice that of 1H-detected PISEMO to account for the fact that real and imaginary part of 15N shift dimension in PISEMO experiment has to be acquired separately.

Article Snippet: The Bruker Avance II console was interfaced with a Chemagnetics 500 MHz power amplifier and a homebuilt transmit/receive switch built with crossed diodes and a λ/4 coaxial cable for 1 H detection.

Techniques: Irradiation, Labeling