Submillimeter spectroscopy using a Froome harmonic generator (metal-plasma junction)

The rectifying properties of the cathode spot of a microscopic arc discharge (as first investigated by K. D. Froome) are used to generate high harmonics of a 37.5-kMc/s source. That these high harmonics can be used to do high resolution spectroscopy in the submillimeter range is demonstrated by a study of the pressure broadening of the J13 → 14 rotational transition of N
2
O at 0.85-mm wavelength.