A Fabry-Perót type resonator tunable below 2 GHz for use in time domain rotational spectroscopy: Application to the measurement of the radio frequency spectra of bromobenzene and iodobenzene

K. C. Etchison, C. T. Dewberry, K. E. Kerr, D. W. Shoup, S. A. Cooke

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Two aluminum mirrors with radii of 203.2 mm and radii of curvature also of 203.2 mm have been used to construct a tunable Fabry-Perót type resonator with Q values of ∼200 at frequencies as low as 500 MHz. The resonator has been incorporated into a pulsed nozzle, Fourier transform, Balle-Flygare spectrometer typically used for recording pure rotational spectra in the microwave region. The resonator design allows the instrument to access the radio frequency region (≤3 GHz) of the electromagnetic spectrum. The spectrometer is of use in (i) recording low J transitions of large asymmetric molecules where the spectra are often greatly simplified compared to higher frequency regions; (ii) measuring hyperfine constants for heavy molecules with higher accuracy than may be obtained at higher frequencies where hyperfine structure may not be resolvable; and (iii) provides further synchronicity between laboratory based measurements and radio astronomy in the 30 cm region. The resonators use is illustrated by recording the rotational spectra of bromobenzene and iodobenzene. The lowest ΔJ = +1 transition for iodobenzene has been observed at 1130.5292(10) MHz.

Original languageEnglish (US)
Pages (from-to)39-45
Number of pages7
JournalJournal of molecular spectroscopy
Volume242
Issue number1
DOIs
StatePublished - Mar 1 2007

Keywords

  • Bromobenzene
  • Iodobenzene
  • Low frequencies
  • Rotational spectroscopy

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