CW NMR/ESR Spectrometer

CW NMR/ESR Spectrometer



Intrinsic Angular Momentum or Spin is a basic property of nuclei and electrons. Although Spin cannot be measured directly, the magnetic dipole moment is closely related and can be observed.


  • Measure NMR/ESR line width
  • Determine g factor
  • Study line shape
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The proton’s larger mass requires a stronger magnetic field than the Helmholtz coils used with the ESR samples. The same probe head can be inserted into the much stronger electromagnet, also arranged in a Helmholtz configuration. The unit can then be tuned to produce a resonance signal for the provided NMR samples or samples made up by the user. NMR Spectra from some of the provided samples shows both hydrogen and fluorine resonance. 

The TEL-CWS12-50 NMR/ESR unit needs no additional accessories. The software for controlling the program is included. Since the unit itself connects to the computer no additional equipment such as an oscilloscope or computer interface is required.

The software allows complete computer control of all parameters, provides for a cursor read out of the data as well as the ability to zoom in on a region of interest. Experimental parameters are selected in a set-up page that can be saved for future data acquisition. A further processing page allows the user to process the data. One can integrate the 1st derivative to obtain an absorption line. The absorption line can be integrated within limits set by the user. In addition calculations of the 2nd and 4th moment can be performed. The line width of the 1st derivative or absorption line can also be calculated. This data can then be saved, exported or printed. 

Data can be accumulated in a single run or in several runs thus providing a better signal-noise ratio for weak signals. 

The user can vary the magnetic field and frequency of a sweep, adjust the receiver gain and the phase of the detector reference signal, and select the time for a single sweep. Data can be acquired in one or over a number of sweeps. The user can choose to display on the screen the last 5 sweeps in different colors. 

An Operations/Experimental manual on CD gives detailed instructions on how to use the software as well as providing directions for performing several NMR/ESR Experiments.





Mode NMR (1H, 19F), ESR

Operational Frequency NMR 1H-13 MHz, NMR 19F-12.2 MHz, ESR-50 MHz

Frequency Stability ≤ 1 PPM/ 1h


    - magnetic field: 300 mT

    - maximum current: 0.7A

    - coil: 2,000 turns

    - gap: 10.5 mm

    - pole diameter: 50 mm

    - homogeneity: ≤ 10-4/sample volume

    - field stability: ≤ 10 μT/1 hr

Helmholtz Coils 

    - magnetic field: 195 μT

    - gap: 15 mm

    - coils diameter: 70 mm

    - homogeneity: 10-5/sample volume

Modulation Field 

    - frequency: 38 Hz

    - amplitude: 0.1-20 μT

Sweep of Magnetic Field (NMR and ESR) 

    - range: 0.5 mT - 10.0 mT

    - time: 0.5 min - 30 min

Sweep of Frequency (only NMR) 

    - range: 20 Hz - 400 kHz

    - time: 0.5 min - 30 min

RF Probehead 

    - solenoid coil dimensions: ID=5.8 mm; L=10 mm

    - mode: Automatically tuned for NMR or ESR


    - gain: 0-48 dB (2 dB step)

    - detection phase: sensitive

    - phase adjustment: 0-360°, step 1.5°

    - signal filter sweep controlled

    - DC offset converter automatic

A/D Converter 

    - resolution: 10 bit

    - number of samples: Min 512 per sweep

Weight and dimensions WxDxH 

    - electronic unit: 3.5 kg, 350x135x85 mm

    - probehead: 0.4 kg, 35x210x70 mm

    - Helmholtz coils: (ESR) 0.5 kg, 50x80x110 mm

    - electromagnet: (NMR)10.5 kg, 175x100x160 mm

Power Consumption 110V/220 V; 50/60 Hz; 40 W

Communication Port two way RS 232C

Computer Required IBM PC, min 750 MHz, VGA color or compatible