WURST pulse generated by AWG at 34 GHz

Depending on the experimental requirements, the AWG is capable of producing 10-100 ns long pulses in the range of 200 to 500 MHz. The RF I/Q mixer converts up to X-band and up to Q-band. Microwave pulses are fed into a 100W solid-state amplifier before being sent to the EPR resonator. The reflected signal is then converted down to an IF frequency in the 200 to 500 MHz range and sent to the digitizer. In an EPR T9481 spectrometer, the signal is usually converted downward to direct current. However, this new method significantly reduces noise and artifacts.

Figure 2 shows an example of the type of pulse generated using AWG in a modern EPR experiment. WURST(Wideband, Uniform Rate, Smooth Truncation) pulses are wideband microwave pulses whose excitation bandwidth and profile far exceed that of a simple rectangular pulse. This pulse allows broadband excitation in the EPR spectrometer, and its performance is closely related to the performance of the AWG.

T9481

A lightweight magnet creates a strong magnetic field

In addition, generating strong magnetic fields on the order of 1 to 1.5 Tesla usually requires a large and heavy electromagnet. Maly explained: “We used a smaller superconducting magnet to generate the required magnetic field strength. In this experiment, the sample always needs to be cooled to a low temperature with liquid helium. Therefore, we found a magnet supplier that does not contain liquid refrigerant (dry). The magnet is small and lightweight, and can produce a high magnetic field of 1.2 Tesla, but is only about 130 kg in size and weight. Instead of using liquid helium, the new product uses a cold head and helium T9481 compressor (which is actually a refrigerator) that can achieve low temperatures in a closed cycle. This is critical because it is becoming increasingly difficult to get liquid helium.”

Maly concluded, “The 5-year warranty provided by Spectrum bolsters our confidence that these products are key components used in EPR spectrometers. Spectrum’s technical support is also top-notch when it comes to setting up devices. If our customers have any problems using the product, we know Spectrum will be a partner we can rely on.”