6 MEASUREMENT OF RELAXATION TIME
6.2 RELAXATION TIME MEASUREMENT BY DIRECT
MEASUREMENT
For the sample that can be measured by a single pulse to obtain the NMR spectrum, you
can perform the relaxation-time measurement by direct observation without using
CPMAS. There are two methods of relaxation-time measurement by direct observation.
•
Inversion-recovery method
•
Saturation-recovery method
The saturation-recovery method is effective for measuring the samples where the T
2
re-
laxation time is small enough in comparison with the T
1
relaxation time.
■
Relaxation-time measurement by inversion-recovery method
The inversion-recovery method is used generally as the relaxation-time measurement
method. Although the measurement procedure is the same as that for a solution, the fol-
lowing pulse sequence is used.
(inversion_recovery.jxp)
(inversion_recovery_dec.jxp)
Refer to the user’s manual “Application” for the measurement and processing of the
inversion-recovery method.
■
T
1
calculation-method for T
1
data obtained by the saturation-recovery
method
The saturation-recovery method saturates the magnetization, and observes the recovery to
obtain the relaxation time. For a peak that changes by a single exponential function, the
strength of the magnetization M (
τ
) is expressed as a function of the delay time (
τ
) by the
following formula in the saturation-recovery method.
M (
τ
) = M
0
{1-exp (-
τ
/ T
1
)}
1.
Load
the pulse sequence
saturation_recovery.jxp
into
Experiment Tool
.
When measuring the T
1
of
13
C, select
saturation_recovery_dec.jxp
.
2.
Set the array parameters for
interval
based on the estimated T
1
value.
Setup the array of values to perform the T
1
measurement (the saturation-recovery
method) in decreasing order. The arrow buttons in Figure 6.1 enable you to switch
between increasing and decreasing order.
6-2
NMECAXS_V50-SLD-2
