Ultimate sensitivity in CW-EPR - SuperX: an ELEXSYS-II feature for the ultimate sensitivity in CW-EPR

The X-Band ELEXSYS-II instruments are equipped with the SuperX feature and the new signal processing unit (SPU). SuperX comprises a selected high-power, ultra-low-noise Dual Gunn source, and the super-high-Q cavity.
The combination of these devices has resulted in an order of magnitude increase in sensitivity for CW-EPR in X-band. For the traditional sensitivity measurement, we specify a weak-pitch signal-to-noise of 3000:1 for the E500 CW-EPR spectrometer.

The SPU is a highly integrated device taking care of all acquisition modes in modern CW-EPR. With a total of 8 signal input channels and various trigger modes, even experiments that are not part of the standard EPR repertoire can be mastered.

One demonstration of the improvement in sensitivity with the SuperX system is shown here for spectra obtained from a Cu²⁺ Histidine in a standard cavity (left) and with the SuperX system (right). What appeared as a weak and uninformative spectrum with the standard cavity is a clear and well-resolved spectrum with the new SuperX system.



Signal Processing Unit (SPU) Features

  • Digital lock-in with up to 5 simultaneously detected harmonics
  • Simultaneous detection of 0 and 90 degree modulation phases
  • Modulation frequencies up to 1 MHz
  • Dual input channels for simultaneous absorption and dispersion measurement
  • 27 bit amplitude dynamic range
  • Rapid scan ramp generator and detection system for modulated and direct detection
  • Transient recorder with 14 bit single shot amplitude resolution and 8 ns time resolution
  • Predefined and user input channels
  • Input channels with AC and DC coupling
  • Internal and External triggers
  • 256 000 points on field and time axis
  • 65 536 points on transient time axis

E 500 Highlights & Standard Features

  • SuperX microwave units for world record sensitivity
  • Ultra high resolution field controller
  • Digital rapid field scan module
  • Stationary and time resolved experiments
  • Multi-purpose signal processing unit (SPU)
  • Reference free spin counting
  • Xepr software package

Computer System

A LINUX based front-end workstation running the Xepr software package a software acquisition server handling all real time events.


X-band sensitivity 1.0 x 109
Weak pitch signal-to-noise ratio 3000 : 1
Modulation frequency 100 Hz to 100 kHz in 1 kHz steps
Modulation amplitude up to 20 G
Field stability 10 mG / hour
Sweep resolution 256 000
Amplitude resolution 32 bit
Detection digital filtering, no time constant needed
  AC and DC input
  dual input channels
Simultaneous detection multiharmonic, up to 5th order
  0° / 90° modulation phase
Transient recorder mode 8 ns time resolution


Service & Life Cycle Support for Magnetic Resonance and Preclinical Imaging

Bruker’s commitment to provide customers with unparalleled help throughout the buying cycle, from initial inquiry to evaluation, installation, and the lifetime of the instrument is now characterized by the LabScape service concept.

LabScape Maintenance Agreements, On-Site On-Demand and Enhance Your Lab are designed to offer a new approach to maintenance and service for the modern laboratory