Accession Number : AD0022005


Title :   THE MEASUREMENT OF ABSOLUTE ABSORPTION INTENSITIES WITH A STARK-MODULATED MICROWAVE SPECTROGRAPH


Corporate Author : HARVARD UNIV CAMBRIDGE MA MALLINCKRODT LAB


Personal Author(s) : Bird, George R


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/022005.pdf


Report Date : 30 Sep 1953


Pagination or Media Count : 12


Abstract : The method developed by D. H. Baird and G. R. Bird for the measurement of relative absorption intensities with the Stark-modulated microwave spectrograph was extended to the measurement of absolute absorption intensities. The determination of absolute intensity is based on the measurement of the ratio of modulation-frequency component to direct component of crystal current at several microwave power levels and the extrapolation of the ratio to zero power. The method was tested on the line CH3CL35J=O 1, F=3/2 5/2 with measured intensities 15% less than the calculated intensity being obtained over a range of 250% in microwave power. Measurements at very low powers are prevented by the presence of a small amount of pickup in the crystal circuits from the square wave generator. Since other sources of error are present, notably multiple reflections in the absorption cell, the uncertainty of this method cannot be evaluated as well as would be desirable. It is not greater than 25% for medium intensity lines, and this is adequate for the identification of asymmetric rotor lines.


Descriptors :   *MICROWAVE SPECTROSCOPY , SOURCES , RATIOS , UNCERTAINTY , INTENSITY , CRYSTALS , ERRORS , CIRCUITS , ABSORPTION , DETERMINATION , RADIOFREQUENCY POWER , SQUARE WAVES , POWER LEVELS , REFLECTION


Subject Categories : Atomic and Molecular Physics and Spectroscopy


Distribution Statement : APPROVED FOR PUBLIC RELEASE