6.21 DOUBLECP1—Double Cross-Polarization
01-999162-00 C0402 VNMR 6.1C User Guide: Solid-State NMR
114
Parameters
doublecp1 uses the
UNITY
INOVA and UNITYplus parameters tpwr, tpwrm, dpwr,
cppwr, dipolr, crossp, dblvl2, pw, and cntct. See page 85 for a description of
these parameters.
dbcpflag is set to 'y' to do double cross-polarization. A Hartmann-Hahn match
between the observe nucleus and third-channel nucleus follows a standard cross-
polarization. The second cross-polarization drains polarization from the observe nucleus
and lowers the signal intensity. If dbcpflag is set to 'n', this second cross-polarization
is omitted. A positive difference signal is obtained by subtracting spectra with
dbcpflag='n' minus dbcpflag='y', or by dbcplfag='y' and third-channel
irradiation off minus on-resonance.
dn2 is the third-channel nucleus.
dof2 is the third-channel decoupler offset, in Hz. dof2 is best obtained by direct
observation of the spectrum of the third-channel nucleus.
dpwr2 is the third-channel coarse attenuator setting (–16 dB to 63 dB).
crossp2 is the third-channel linear modulator setting (0 to 4095). The parameters
crossp and crossp2 determine the Hartmann-Hahn match for the dilute-spin cross-
polarization. The dilute-spin Hartman-Hahn match is determined with DOUBLECP1.
Figure 50. DOUBLECP1 Pulse Sequence
pw cntct
(crossp)
(dipolr)
cntct
(tpwrm)
Tx
Dec2
Dec
cntct2
(crossp2)
<if dblcpflag='y'>
ABCC
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