Abstract

For the past few years we have been making isotopic ratio measurements on a variety of metals using a surface ionization type source. In certain applications, it is desirable to search for isotopes which are present in very small amounts. A specific difficulty has been encountered in searching for an isotope adjacent to another isotope of the same element in which the ratio of the large to small isotope is of the order of 10⁴. As is well known, the resolution of a mass spectrometer is a function of a number of parameters. The first is the radius of curvature of the analyzing magnet; this factor determines the dispersion. Secondly, the width of the source and detector slits is a limitation. That is, if the slits are very small, the beam will be attenuated; on the other hand, as the slit widths approach the dispersion distance, it becomes increasingly difficult to resolve adjacent isotopes. A third, and also important factor, is the energy spread of the ions leaving the source. This energy spread arises from the I. R. drop in voltage across the surface ionization filament as well as from the kinetic energy distribution of ions produced by the surface ionization mechanism.

Ultrasensitive laser isotope analysis in an ion-storage ring

J. J. Snyder, T. B. Lucatorto, P. H. Debenham, and S. Geltman
J. Opt. Soc. Am. B 2(9) 1497-1502 (1985)

Selective isotope determination of lanthanum by diode-laser-initiated resonance-ionization mass spectrometry

J. P. Young and R. W. Shaw
J. Opt. Soc. Am. B 12(8) 1398-1402 (1995)

First field determination of the ¹³C/¹²C isotope ratio in volcanic CO₂ by diode-laser spectrometry

A. Castrillo, G. Casa, M. van Burgel, D. Tedesco, and L. Gianfrani
Opt. Express 12(26) 6515-6523 (2004)

Measurement of the isotope selectivity of the strontium magneto-optical trap by a time-of-flight mass spectrometer

Kwang-Hoon Ko, You-Kyoung Lim, Do-Young Jeong, Hyunmin Park, Taek-Soo Kim, Gwon Lim, and Hyung Ki Cha
J. Opt. Soc. Am. B 23(12) 2465-2469 (2006)

A Two-Wavelength Two-Frequency Ratio Recording Infrared Spectrometer Analyzer

A. M. Bartz and H. D. Ruhl
Appl. Opt. 2(9) 969-973 (1963)