Showing papers by "Charles H. Townes published in 1974"

Infrared Pumping Processes for SiO Masers

Abstract: The J = 2 to 1 transition of the first excited vibrational state (v = 1) Si(28)O(16) has recently been shown to produce maser amplification near 86,245 MHz in Orion A and in several stars. Two possible pumping mechanisms are proposed for such masers. One involves the near coincidence between the frequencies of the 1-0 (RO) and 3-2 (R18) transitions in Si(28)O(16). The other requires emission by SiO and reabsorption without the necessity for an accidental frequency coincidence. Each of these types of mechanisms may occur for other transitions of molecules in a medium illuminated by intense infrared radiation, or with strong temperature gradients.

Isotopic Abundances and Their Variations within the Galaxy.

Abstract: Ihe relative abundances of isotopic species in parts of the Galaxy ouLtside the solar system represenlt an important record of the past, and one which is bccomiing increasingly available throuLgh mleasuLremiienlt of molecCUlar spectra in interstellar clouLds and in stellar atmospheres. Informiiation on isotopic abuLndanices in interstellar miaterial from microwave molecuLlar spectra, along s ith a sm-nall amlouLnt of informiiation fromii other spectral regions, is assemnbled and analyzed here to obtain

10-micron heterodyne stellar interferometer

Abstract: A spatial interferometer for 10-micron wavelength which uses two independent telescopes separated by 55 m, heterodyne detection of the infrared radiation, and path equalization by a variable-length RF cable, has given interference fringes from radiation of the planet Mercury Continuous fringe observations during 4000 sec indicate remarkable stability in the optical-path difference through the atmosphere and the two telescopes, fluctuations between 20-sec averages being about 1/6 of the 10-micron wavelength