Paper 2.5: "Radiofrequency Spectra of Hydrogen Deuteride in Strong Magnetic Fields," W. E. Quinn, J. M. Baker, J. T. LaTourrette and N. F. Ramsey, Phys. Rev. 112, 1929–1940 (1958)
Reprinted with permission from The Physical Review. Copyright 1958, The American Physical Society.
Since the molecules H2, D2 and HD are the simplest polyatomic molecules and since we could measure many of their parameters with unprecedented accuracy, I decided that they deserved to be studied thoroughly. After completing the precision studies on the H2 and D2 nuclear resonances, my students and I used the same apparatus to study the spectra associated with the reorientation of the rotational magnetic moments of H2 and D2. We observed the variations of rotational magnetic moments with rotational quantum numbers and isotopic masses and determined the electron distribution in the hydrogen molecule [N. J. Harrick and N. F. Ramsey, Phys. Rev. 88, 228–232 (1952) and R. G. Barnes, P. J. Bray and N. F. Ramsey, Phys. Rev. 94, 893–902 (1954)].
We next wanted to study HD, but there are twice as many resonances in the first rotational state for HD as for H2, so the observed intensities were too low for precision measurements. By then G. Wessel and H. Lew had developed an electron bombardment detector that worked well with condensable vapors, so my associates and I developed an electron bombardment detector and vacuum system that also worked with noncondensable gases such as H2, D2 and HD [W. E. Quinn, A. Pery, J. M. Baker, H. R. Lewis, N. F. Ramsey and J. T. LaTourette, Rev. Sci. Instrum. 29, 935–943 (1958)]. This detector was first used to study HD (Paper 2.5). We measured the radiofrequency spectra in both the zeroth and first rotational states. The results were consistent with previous measurements and with the theory given in Paper 5.7.
Thirteen years after Paper 2.5, R. F. Code and I [Phys. Rev. A4, 1945–1959 (1971)] remeasured HD and D2 with even better accuracy by using a very low magnetic field, the improved apparatus described in Paper 2.6, an electron bombardment detector and a 20 K source cooled by gaseous helium [Rev. Sci. Instrum. 42, 896–898 (1971)]. That experiment gave more accurate interaction parameters and a confirmation of the electron-coupled spin–spin interaction theory of Paper 5.5.
