Determination of Atomic Masses by Microwave Methods
The development of microwave techniques in the last decade has resulted in another tool for the accurate determination of atomic masses. The characteristic rotational frequencies of molecules lie in the microwave region (electromagnetic spectrum from about 1 to 300 mm in wavelength) and comprise the bulk of the microwave spectra of gases. By measuring the frequency shift which occurs in the pure rotational absorption spectrum of a molecule when another isotope is substituted for one of the atoms, accurate information about the relative masses of the isotopes can be obtained.
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- Townes , C. H., and A. Schawlow: Microwave Spectroscopy. New York: McGraw Hill 1955 — This excellent book is the most complete and detailed treatment to be found of both the theoretical and experimental aspects of the microwave spectroscopy of gases. Parts of chapters 1, 2, 3 and 8 contain accounts and information dealing with microwave mass determinations.Google Scholar
- Strandberg , M. W. P.: Microwave Spectroscopy. London: Methuen & Co. Ltd.; New York: John Wiley & Sons, Inc. 1954. — A compact treatment emphasizing quantum mechanical matrix methods in deriving the energy levels of a rotating molecule. The electronic contribution to the moment of inertia of molecules is discussed in Chap. VI and VIIGoogle Scholar
- Gordy, W., W.V. Smith and R. F. Trambarulo: Microwave Spectroscopy. New York: John Wiley & Sons, Inc. — A general survey including accounts of microwave spectra of solids such as paramagnetic and ferromagnetic resonance.Google Scholar
- “Symposium on Microwave Spectroscopy”. Ann. N.Y. Acad. Sci. 55, 751 (1952). — Collection of papers on various topics in microwave spectroscopy presented at the Conference. Molecular spectra.Google Scholar
Nuclear mass compilations
- “Mass Differences — A compilation of experimental atomic mass differences from/5-decay, reaction energies, microwave data, alpha decay and mass doublets”. Rev. Mod. Phys. 26, 327 (1954).Google Scholar
- Wapstra, A. H.: Isotopic Masses, Physica, Haag 21, 367 (1955). — Part I contains a computation of isotopic masses for A < 34 obtained from nuclear reaction data. Part II contains a computation of masses for A = 33 to A =202 using data from all the techniques of mass determination. (See also Wapstra’s preceding article in this volume.)ADSCrossRefGoogle Scholar