First obtain ¹H and ¹³C spectra of the sample and note the offsets of the CHCl₃ signals. The instrument must be in the inverse mode, using the proton channel as transmitter and the ¹³C channel as decoupler. You have to set:

td	4 k
o1	on ¹H resonance
o2	on ¹³C resonance
sw	500 Hz
p1	135° ¹H transmitter pulse
p2	180° ¹H transmitter pulse
p3	45° ¹H transmitter pulse
p4	180° ¹³C decoupler pulse
d1	20 s
d2	1/[2J(C,H)] = 2.38 ms, calculated from ¹J(C,H) = 214 Hz
ns	8

5. Processing

Use standard ¹H processing as described in Experiment 3.1 with exponential multiplication of lb = 1 Hz.

6. Result

Proton spectrum after the TANGO sequence on chloroform

The figure shows the result obtained on an AMX-500 spectrometer with an inverse probe-head. Note that the suppression of the central signal is less efficient compared to the BIRD sequence of Experiment 6.13, since only slight misadjustments of the pulse-lengths cause a central signal.

7. Comments

For analysis with the product operator formalism we consider first a proton bonded to ¹²C and thus not able to develop C,H spin coupling. The effects of chemical shifts are