Power supply unit for field gradient with high stability and high power

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NM060021E

A new 30A power unit for field gradients provides 3 times the power and the equal stability of a standard power unit in JNM-ECA/ECX series.
This unit can supply field gradient pulses up to 90G/cm when used with a standard tunable probe (TH5AT/FG probe) and is suitable for measurements of diffusion coefficients and DOSY of polymers.
30A磁場勾配電源

In NMR spectroscopy, a diffusion coefficient is determined by fitting or calculation for the following decay curve of signal intensity I(G):

γ: Gyromagnetic ratio
G: Field gradient strength
δ: Field gradient pulse width
Δ: Diffusion time
D: Self diffusion coefficient

A maximum value of Δ is limited by the relaxation time of a sample, while δ isusually the order of ms regardless of NMR systems. Consequently, strong field gradients are required to obtain a sufficient decay in the case of small diffusion coefficients (see below). If a decay is not sufficient because of weak field gradients, the resultant diffusion coefficient becomes less accurate and the separation in DOSY spectra becomes ambiguous.

Example of decay measurements

Sample: polyethylene glycol
(Molecular weight: 35,000)
Solvent: D2O
Temperature: 30℃
 
Experimental conditions:
A. Diffusion time Δ = 0.4 s
   Field gradient pulse width δ = 8 ms
   Filed gradient strength G = 5-15 G/cm
 
B. Diffusion time Δ = 0.4 s
   Field gradient pulse width δ = 8 ms
   Filed gradient strength G = 5-30 G /cm
 
C. Diffusion time Δ = 0.4 s
   Field gradient pulse width δ = 5 ms
   Filed gradient strength G = 5-90 G /cm

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