JEOL JES-X3 Series ESR Spectrometers

A new design of microwave unit. Much better sensitivity using ‘High Sensitivity Mode’

Electron Spin Resonance (ESR), also known as Electron Paramagnetic Resonance (EPR), is a powerful analytical method to detect, analyze and determine the characteristics of unpaired electrons in a substance. It is clear that the state of electrons in a substance have a strong influence on its characteristics and functionality, so evaluation by ESR is becoming more and more important. Many types of substances, from electronic materials to catalysts to biological samples can be studied regardless of whether they are solid, liquid, or gas. A wide range of ESR techniques are possible using suitable attachments together with the basic instrument.

Recently, it has been widely accepted that even relatively few unpaired electrons in a sample can affect the function of the material, so lower detection limits (higher sensitivity) is required of ESR measurements. JEOL has achieved higher sensitivity by developing a low-noise Gunn oscillator for its new spectrometer, the JES X3 series.

New functions for data acquisition and analysis enable a smooth transition from initial experiment selection to final detailed measurement.

  • New Auto-tuning that has better reproducibility and shorter tuning time.
  • Fully flexible sequential measurements including randomized values of parameters, e.g. sample temperature, microwave power, etc.
  • A foot operated trigger (option) to start data measurement can be used to minimize dead time after reagents are mixed to generate short lived radicals.


Major New Functions

  • Easy-to-use operation interface under Windows10™
  • Hands-free measurement start using foot switch.
  • Both progressive and randomized settings of sequential measurement parameters possible.
  • Improved display of multi-dimensional data.
  • Batch processing of sequentially measured data, including background subtraction.


Major Features

  • For measuring radicals generated by photo-irradiation, the standard universal cavity has an optical irradiation window which has high transmittance.
  • High stability Auto-tuning.
  • Each attachment easy to attach and detach.


The JES-X3 Series Product Brochure

You can also read an in-depth published article on the history of JEOL NMR and ESR

  Pole Diameter Pole Gap Max. Field (T) Homogeneity Sensitivity
JES-X310 15 cm 60mm 0.65 5 x 10-6 5 x 109 spins / 10-4 T
(at 100 kHz modulation)
JES-X320 24 cm 62mm 1.30 5 x 10-6 5 x 109 spins / 10-4 T
(at 100 kHz modulation)
JES-X330 36 cm 75mm 1.40 5 x 10-6 5 x 109 spins / 10-4 T
(at 100 kHz modulation)


JEOL Resources

Documents of interest in support of your JEOL product

Strong interaction between light and electrons (6) "Coupling constant and line width"

Application Note ER200011E

When an ESR spectrum of paramagnetic sample is measured in the state subjected to the Purcell effect, its line width broadens extraordinarily as shown in Application Note ER200006E. It would be a serious problem in which we must reduce the filling factor when a sample which has many spins is measured using a cavity. This is not a problem only with a ferromagnetic sample, but also with a paramagnetic one as well. How much should we reduce the filling factor by? To obtain a rough guide for it, ESR spectral line widths (ΔHpp) and shift widths of cavity frequency (Δf) were simultaneously measured on the respective sample position moved as shown in Fig. 1(a).

A drawing of the experiment which investigates a relation with sample moving and line width.
(a) Sample location in the cavity. (b) Measurement examples of Δf(upper) and ΔHpp (lower).

Relationship between frequency shift and line width in the state subjected to Purcell effect

As increasing the sample amount, frequency shift width also increases. Thus, it can be considered that there is a correlation between coupling constant 𝑔𝑚 and frequency shift Δf in the state subjected to the Purcell effect. Simulation results of frequency shift widths at several 𝑔𝑚 values based on S11 equation[1][2] show a correlation according to quadratic function related to 𝑔𝑚 (conf. Fig. 2(a)). In this simulation, we have set Qu = 18000 and 𝛾𝑚 ∕ 2𝜋 (HWHM) = 3.39 MHz. Therefore, it can be considered that the observed line width ΔHpp is proportional to ∆𝑓, because ΔHpp is proportional to g2m[2]. As a result, by plotting ΔHpp at respective ∆𝑓, sample intrinsic line width and optimal filling factor (optimal sample position) can be estimated. As shown in Fig. 2(b), ΔHpp can be fitted by linear function. By moving a sample to the position until the line width is no longer changed (in this case, more than + 30 mm), Normal spectrum and analysis which is not affected by a strong interaction between photon and spins is capable, even if spin density is high. This is a little troublesome experiment. However, this experiment is also effective on ESR/FMR measurements using more concentrated magnetic samples. Using this plot would be useful to study about the effect of the interaction between photon and spins.

(a) Simulation results about the relation with 𝑔_𝑚 and Δf .  (b) Spectral line width ΔHpp plotted at respective observed Δf.

[1] E. Abe, H. Wu, A. Ardavan, and J. J. L. Morton, Appl. Phys. Lett. 98, 251108 (2011).
[2] Patent, US10288707B2 "Relaxation time measuring method and magnetic resonance measuring apparatus".

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