We have measured the ac Josephson effect in Nb point contactsat 604 GHz (496 μm). We find the coupling of the far‐infrared radiation to the point contact to depend in a simple manner on the resistance of the contact. The behavior of the high‐resistance point contacts (50⩽R⩽200 Ω) is very reproducible, allowing a quantitative comparison of the data to the frequency‐dependent Werthamer theory. We also account for the effects of noise and heating and compare these to Tinkham’s heating theory.
Wavelength measurements of 160 13C16O laser lines in the range from 1500 to 1900 cm−1 have been made with a conventional grating spectrometer. The accuracy of the measurements is about ±0.003 cm−1. Although more precise measurements of these lines will ultimately be made using microwave beating techniques, the present results should be of interest for the determination of improved molecular constants for CO and especially for the various spectroscopic applications of the CO laser.