Setting up non-uniformly sampled spectra/NUS guide for Bruker according to Arrowsmith group in Toronto

=== Setting up acquisition of non-uniformly sampled data on Bruker spectrometers with TopSpin ===

A standardized way to set non-uniform sampling (NUS) for TopSpin is in the making, however, while it is not yet included in the current distribution, this page will focus on the way implemented by the Arrowsmith group in Toronto (University Helath Network and University of Toronto). It is taylored for the subsequent processing with MDDGUI software, described elsewhere on this site.

To set up 3D NUS experiments according to this method one needs the following:

• Modified pulse program(s)
  
• A Jython script for generating the sampling schedule
  

Pulse program modifications

This section briefly describes the essential pulse sequence modifications. The 15N-NOESY-HSQC pulse program is used as an example. In most cases one just need to copy these changes into relevant pulse program.

• Additional definitions should come with other definitions in the file:
  

;********Added for NUS*******
define delay short
"short=50u"
"l2=td2/2"
"l3=td1/2"
;^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Main if statement determines whether an Echo/AntiEcho or Real/Imaginary pair is recorded or skipped. The information is taken from the vdlist file, If the current value of vd is 1u, the pair is skipped (goto 100 statement), if it is 3u, it is recorded. generated by the script mentioned above before running the experiments. This addition replaces the text commented out and comes before the d1 delay:
  

;1 ze
;  d11 pl16:f3
;2 d11 do:f3
;3 d12
;********Added for NUS*******
1 ze
	d11 pl16:f3
2	d11 do:f3
	short*2
3	short*5
4	1u
if "vd < 2u" goto 100
	short*6
5	short
6	d11
;^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  d1 

• The final modification comes at the end of the pulse program and uses explicit looping (old style Bruker pulse programming). Note that F1PH and F2EA statements are commented out and the phase and delay increments or decrements are stated explicitly. These increments or decrements need to be executed even if the particular fids are skipped

  go=2 ph31 cpd3:f3
;********Added for NUS*******
	d11 do:f3 wr #0 if #0 zd
;----------------------------
100     short igrad EA             ; even if the pair is skipped, phases have to be increment appropriately. 
	short ip5*2                ; especially important if Complex or States-TPPI mode used for this dimension
lo to 3 times 2                    ; end of Echo-AntiEcho loop

	short id10                 ; increment delay and phases for 15N
	short ip3*2
	short ip6*2
	short ip31*2
	short ivd                  ; check the next value of vd
lo to 4 times l2                   ; go back to beginng with the new vd value

	short rd10                 ; reset 15N delays and phases
	short rp3
	short rp6
	short rp31
	short ip8                  ; increment 1H-indirect phases
	short ip9
lo to 5 times 2                    

	short id0                  ; increment 1H-indirect delay.
lo to 6 times l3
1m
;^^^^^^^^^^^^^^^^^^^^^^^^^^^^
;  d11 do:f3 mc #0 to 2 
;     F1PH(rd10 & rp3 & rp6 & rp31 & ip8 & ip9, id0) 
;     F2EA(igrad EA & ip5*2, id10 & ip3*2 & ip6*2 & ip31*2)
exit