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A new Breakthrough

Classical pulse-EPR has been using single frequency, square-shaped microwave pulses for decades. For around 10 years, a second microwave frequency has been widely used for Electron-Electron Double Resonance (ELDOR) experiments. Pulse shaping and a higher degree of pulse flexibility have been hindered by the lack of any suitable high speed digital technology. Now, with the technology of Arbitrary Waveform Generators (AWG) we can take the next step in pulse-EPR. All waveform features that can be described mathematically can now be implemented in a pulse sequence - a true breakthrough for pulse-EPR.

The SpinJet-AWG introduces a new era in pulse EPR. With several examples, we demonstrate the exciting new opportunities and possibilities available. For ease of operation, complete control over the pulse parameters - including frequency, shape, phase and amplitude - is fully implemented in Xepr. User definition of experiments is further extended via PulseSPEL. Compensation of technical limitations and restrictions imposed by sample properties can be addressed via the optimum control methodology. This methodology is expected to lead to significant improvements in all fields of pulse-EPR spectroscopy. The Optimum Control Pulse waveform definition is readily available from the Xepr interface (tables and PulseSPEL).

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Features

 

  • Frequency definition for each pulse
  • High resolution phase setting
  • Pulse shapes within shot
  • Pulse amplitude control within shot
  • Frequency chirps within pulse
  • Multiple channel architecture
  • Overlapping pulses
  • Optimum Control Pulse input function
  • Full Xepr implementation
  • I/Q vector modulator with LO suppression network
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Overlapping channels

Compability:

 

  • The SpinJet-AWG is an accessory for the X-band FT-EPR bridge. All its features directly transfer via the IF path to other bands as well.

  

  • Compatible with the E 580/680/780 instruments optimized for instruments based on the Linux acquisition server.

 

 

 

Specifications:

 

  • Amplitude resolution 14 bit
  • Clock 1.6 GS/s
  • 0.625 ns time resolution
  • Up to 16384 individual waveforms per acquisition cycle
  • Up to 32 channels
  • 5 predefined shapes
  • Support for custom shapes
  • Memory corresponding to 80 ms of continuous pulsing
  • ± 400 MHz bandwith around carrier

 

 

Resolution improvement in ELDOR

Resolution improvement in ELDOR detected NMR by a Gaussian high turning angle pulse.

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EPR spectrum measured by FT of the chirped echo

An EPR spectrum of 100 G (280 MHz) width was measured by FT of the chirped echo. In this way measuring time is reduced drastically by the multiplex advantage. There is some amplitude reduction of the outer lines due to receiver bandwidth limitation but the achieved excitation bandwith can not be obtained by a single frequency pulse.

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¹H HYSCORE of nitroxide spin probe

¹H HYSCORE of nitroxide spin probe: (right) 166 ns chirped (±113 MHz) inversion pulse and (left) 26 ns standard inversion pulse.

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Inversion Pulses

The excitation bandwidth of the inversion pulses are indicated on the field sweep spectrum, red = chirped and blue = standard.

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