JNM-ECA Series JNM-ECX Series JNM-ECS Series - George Fox ...

2 MEASUREMENT OF DIFFUSION COEFFICIENT
2.3 MEASUREMENT OF DIFFUSION COEFFICIENT (D)
As discussed above, the measurement of the diffusion coefficient can be carried out by
changing either the field-gradient strength G, the duration of gradient pulse δ, or the
time between two FG pulses Δ.
However, in the measurement in which a time parameter such as the duration of the field
gradient pulse δ or time between FG pulses Δ changes, you have to take into account
the influences time, such as relaxation. Therefore, the measurement by changing
magnetic-field-gradient strength G is presently in general use. The procedure for
measurement of the diffusion coefficient by changing the magnetic-field-gradient
strength G is explained below.
■ To obtain measurement conditions
1. Stop the sample spinning, and tune the probe.
2. Check the 90° pulse width.
In order to improve the accuracy of the diffusion coefficient measurement, we
recommend that you check the 90° pulse width of the sample you are measuring.
For checking the 90° pulse, perform an array measurement using the
measurement mode single_pulse.ex2 or single_pulse_dec.ex2.
3.
4.
Click on the Expmnt button in the Spectrometer Control window.
The Open Experiment window opens.
Click on diffusion.
5.
6.
Select the desired sequence from the File name list.
The Experiment Tool window for setting up parameters opens.
Input the following value if needed.
The values of x_pulse and gradient_max of the following are recalled automatically
from the default values in the probe file. Input values when values obtained in
step 2 differ from the values in the probe file.
2-4 NMECA/ECX-USA-3