The Nuclear Magnetic Moment ofTc99

Abstract

479value of the spin of Ti of either 3.1"±0.4 or 3.7±0.4, depending upon whether the isotopic abundance is taken to be that of Ti 47 or Ti 49 , respectively. This would indicate that the spin is probably 7/2 and that the signals are probably due to Ti 49 instead of Ti 47 , although this measurement is not conclusive because of uncertainties in the degree of dissociation. From the observed optimum signal to noise ratios of the Ti resonances in various samples we can also estimate the spin to be 7/2±l. Since we have observed the magnetic moment to be negative, this indicates an ft/2 state for the odd neutron, which is not in disagreement with the predictions of the nuclear shell model. 6 Assuming, then, that the spin is 7/2 we find from (1) that the diamagnetically uncorrected value of the magnetic moment of Ti 49 (or perhapswhere we have taken the proton moment to be 2.7925 nm. We have searched over a wide region for the resonance signal from the other odd Ti isotope, but have as yet failed to find it, probably because the gyromagnetic ratio is small. We have observed the nuclear magnetic resonance of As 75 in a 1.2 molar aqueous solution of NasAsS4 and also in a basic aqueous solution of Na3As04. The Na3AsS4 sample gives a large signal, with a half-width of about 0.7 gauss; the line width is limited by quadrupole broadening, which is not excessive in this case because the sample is well dissociated into symmetric (AsSJ" ions. On the other hand, it was found that in the NasAs04 sample the As resonance signals were obliterated by excessive quadrupole broadening unless the sample was made basic (by the addition of NaOH) to a pK>12. This is in agreement with the chemical evidence that Na 3 As04 does not dissociate into (ASO4) ions, except in basic solution. 7 We have not detected a " chemical shift" 5 between the As resonance frequencies in (ASS4) and (ASO4) . The ratio of the As 75 resonance frequency to that of protons in H 2 0 in the same magnetic field has been found to be *'AS75AH = 0.17129±0.00003.(3)The spin 8 of As 75 is known to be 3/2, and we have verified this by comparing the As 75 signal from Na 3 AsS4 to the D 2 signal in D2O; our experimental result is 7(As 75 ) = 1.5±0.2. Taking the proton moment to be 2.7925 nm, we find from (3) the diamagnetically uncorrected value of the moment of As 75 to be /x(As 75 ) = + (1.4350±0.0003) nm.This value is in agreement with that recently reported by

99Tc NMR Spectroscopy

“…The 99 Tc NMR was first observed in aqueous solution of ammonium pertechnetate in 1952 [5]. The ratios of the technetium resonance frequency to the resonance frequencies of proton and deuterium were determined, and the magnetic moment of technetium nuclei was measured to be +5.6805 + 0.0004 nuclear magnetons.…”

“…Table 7 shows that the chemical shift for tricarbonyl complexes Tc(CO) 3 + varies in a wide range depending on the additional ligand. In addition, a weak influence of the solvent on the chemical shift was noted [44]: the chemical shift for trans-TcCl(CO) 3 (PPh 3 ) 2 varies from 31481 to 31488 ppm with substitution of C 6 D 6 for CD 2 Cl 2 , and for Tc(CO) 5 Br, from 31802 to 31830 ppm. In addition, a weak influence of the solvent on the chemical shift was noted [44]: the chemical shift for trans-TcCl(CO) 3 (PPh 3 ) 2 varies from 31481 to 31488 ppm with substitution of C 6 D 6 for CD 2 Cl 2 , and for Tc(CO) 5 Br, from 31802 to 31830 ppm.…”