Standard Article

New Techniques in Microwave Spectroscopy

  1. Steven T. Shipman,
  2. Brooks H. Pate

Published Online: 15 SEP 2011

DOI: 10.1002/9780470749593.hrs036

Handbook of High-resolution Spectroscopy

Handbook of High-resolution Spectroscopy

How to Cite

Shipman, S. T. and Pate, B. H. 2011. New Techniques in Microwave Spectroscopy. Handbook of High-resolution Spectroscopy. .

Author Information

  1. University of Virginia, Department of Chemistry, Charlottesville, VA, USA

Publication History

  1. Published Online: 15 SEP 2011

Abstract

We discuss the design principles and performance of a true broadband chirped-pulse Fourier transform microwave spectrometer capable of operation from 800 MHz to 18.5 GHz. This spectrometer utilizes recent advances in high-speed digital electronics to both directly generate linear frequency sweeps spanning more than 10 GHz and to directly digitize the molecular free induction decay (FID). Signal averaging is performed in the time domain to improve the signal-to-noise ratio. This spectrometer has a number of capabilities that are well suited for studies on large-molecule systems, including the ability to perform multiplexed Stark effect measurements and selective-excitation microwave double-resonance measurements. These characteristics are demonstrated using the molecule 1,2,2,2-tetrafluoroethyl difluoromethyl ether (C3H2F6O, molecular weight 168 g mol−1, also known by its trade names of suprane or desflurane) as an example. The simultaneous use of multiple-pulsed nozzles as well as the acquisition of multiple FIDs per valve pulse is also demonstrated in the context of strategies for increasing spectrometer sensitivity by 2 orders of magnitude.

Keywords:

  • chirped pulse;
  • large-molecule spectroscopy;
  • FTMW;
  • broadband;
  • selective excitation;
  • Stark effect;
  • suprane;
  • Fourier transform microwave spectroscopy