Calibrate 90º ¹³C Pulse

¹³C (or ¹⁵N) pulses should also be calibrated. However, these pulse are less dependent upon sample than the ¹H so previous calibrations should be close. Since ¹³C (or ¹⁵N) is being pulsed on the 2nd (3rd) channel, direct detect calibrations should not be used. Thus, the best way is to calibrate the pulse is to look for maximum signal in the HMQC (or HSQC). The parameter of the high power 90º pulse on ¹³C in experiments is normally pwC or pwx (pwN for ¹⁵N), check you parameter set to confirm this as there in not a standard convention on X nuclei 90º pulse parameter names. The power of that pulse is NOT dpwr, it is usually pwClvl or pwxlvl, again there is no convention on parameter names except dpwr refers to the power of decoupling (low power) (dpwr2 = low power ¹⁵N). To measure ¹³C high power 90, array the pwC (or whatever the high power pulse is called in that experiment) at high power level pwClvl=60. Again dpwr is not the right parameter and should never be > 49. This time look for maximum signal, this is the best pwC to use.