Developments in high-speed digital electronics have enabled the development of spectrometers for broadband molecular rotational spectroscopy.  These spectrometers use chirped-pulse excitation to polarize the molecular sample over bandwidths on the order of 10 GHz.  The resulting free induction decay is digitized and the broadband frequency domain spectrum is obtained through fast Fourier transform.  Using this approach, a broadband spectrum can be acquired for each individual laser excitation pulse for dynamics experiments that couple molecular rotational spectroscopy and laser excitation to create highly excited states or to generate reactive species.  Applications of pulsed-jet chirped pulse Fourier transform rotational spectroscopy at microwave frequencies (2-40 GHz) will be presented that use dynamical effects in the rotational spectrum of highly excited molecules to measure unimolecular isomerization rates.  Advances in solid-state devices for mm-wave/THz spectroscopy have made it possible to extend these techniques to the 260-290 GHz range for application to room-temperature samples.

Chirped-pulse Fourier transform rotational spectroscopy

245th National Meeting (2013)

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