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
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'>
A
B
C
C