By Larry Desjardin, Modular Methods
I had the fortune to speak with Dr. Steven Shipman, a chemistry professor at New College of Florida. He’s a rotational spectroscopist, which means he watches how molecules rotate, and uses that to learn about them. A molecule’s rotation is a function of its three dimensional shape, so its rotational spectrum acts as a “molecular fingerprint”, unique to it. While rotational spectroscopy has many applications, Dr. Shipman’s research focuses on astrochemistry. He is trying to find out how and why complex molecules formed in interstellar space, and ultimately how our life-bearing planet came to be the way it is. Along the way, he also has interest in continually pushing the technology to make better and faster measurements. That’s where AXIe comes in.
To understand the measurement challenge, it is important to understand how rotational spectroscopy measurements are made. A chirped pulse is created that shifts from 0 to 5GHz in 250ns. To create this chirped pulse, Dr. Shipman uses an AXIe Arbitrary Waveform Generator, the Agilent M8190A. It is a two channel AWG in a double-wide AXIe module that can sample up to 12Gs/s. This pulse is filtered, frequency shifted up to 26.5GHz, and amplified using a variety of external microwave components.
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