2.5 Arraying

Type the values you want for a variable. For ex. pw=1, 5, 6, 11, 21.

Or type array and answer the prompt questions.

It can be a good idea to use interleave. For example, the command (set s2pul pw=3,6,9 nt=16 bs=4 il='y') does the following:

• calls the s2pul pulse sequence,
• sets three values of pulse width (pw=3,6,9, in microseconds),
• sets the total number of transients to 16, for each pw value,
• sets the block size (bs) to 4 (this is a division of nt),
• and sets interleave to yes. This makes the spectrometer scan bs increments of spectra (4 in this case) using pw=3, and then switch to pw=6 in the next bs increments, and then to pw=6 ...

If il='n' all the nt increments would be first scan with pw=3. If you are arraying gradient values, for example, it would be good to oscilate among high an low values so that the coils and the PFG amplifier can ``cool'' at lower currents instead of standing a long time (all the nt increments) at high currents.

Advantages of using interleave:

• when using array of high power for wharever you can rest your sistem in low values during each cycle;
• you can set a high value for nt (say 8589934592), provided that bs is not so high. So that you can stop the expt. before the predicted end and still have spectra for all array values.

Other interesting variables:

ss:

Seting il='y' ss=-2, for example, will discard the 2 first scans at the begining of each bs.

array:

This variable stores the arrayed parameters. If you enter s2pul pw=7,8 d1=2,3, the array variable will be pw,d1. It means that d1 hast precedence over pw. If il='y' bs=4, the following order will be used:

• scans 1 to 4: pw=7 d1=2
• scans 4 to 8: pw=7 d1=3
• scans 8 to 12: pw=8 d1=2
• scans 12 to 16: pw=8 d1=3

You can enter array='d1,pw' to give precedence to pw.