Magnetic Resonance Absorption in Nitric Oxide

Abstract

The nine-line magnetic resonance spectrum of N"0" is observed at 6elds in the range of 8600 oersted at a frequency of 9360 megacycle/sec. The spectrum arises from magnetic-dipole transitions between Zeeman levels in the J=-, state of the 'II3~~spin component. The line positions allow a determination of the magnetic IJ coupling constant, which is 29.8~0.3 megacycle /sec. , and the nuclear electric quadrupole coupling, which is -1.7~0.5 megacycle /sec, The line position and triplet spacings, which arise from molecular perturbations, are in good agreement with the theory of Margenau and Henry. The absolute intensity of the three stronger lines is measured to be g"=1.2X10 ' which also agrees with theory.

EPR study of NO adsorption-desorption behaviour on Lewis acid sites in NaA zeolites

“…5 It seems noteworthy that no EPR signal of the 2  3/2 state could be detected within the zeolite material at any temperature. To check whether the appearance of the 2  3/2 signal for T > 150 K is actually related to the desorption of the nitric oxide from the zeolite material, we determined the intensities of the EPR signal of the 2  3/2 state of gaseous NO as a function of the temperature in a tube without any adsorbing material as shown in Fig.…”

“…The centre of gravity of the nine-line spectrum will be at about 890 mT at X band frequencies corresponding to an electron Zeeman splitting factor of g ³ 0.7772. 5,6 The above considerations for the freely rotating NO molecule no longer hold when the nitric oxide is adsorbed, for instance, on a metal oxide surface or a cation in a zeolite matrix. Then, the strong electric field at the adsorption site quenches the orbital angular momentum 7 -9 10 It seems to be noteworthy that  might be considered as a measure for the electric field at the adsorption site of the probe molecule.…”

“…The energy separations of these levels are slightly different owing to perturbations of nearby states. 5,6 The hyperfine (hf) interaction between the unpaired electron and the 14 N nuclear spin I D 1 gives rise to a further triplet splitting of each m J sublevel. Thus, the EPR spectrum will exhibit three triplets according to the selection rules J D 0, m J D š1 and m I D 0.…”

Adsorption and Desorption Behavior of NO on H-ZSM-5, Na-ZSM-5, and Na-A as Studied by EPR

“…In this work our approach is used to study NO adsorption at sodium cations in A type, and aluminum defect centers, so-called "true" Lewis acid sites, in ZSM-5 type zeolites. This particular adsorption-desorption method takes advantage of the specific magnetic properties of gaseous NO molecules (10) that have been extensively studied by EPR (11)(12)(13) and microwave absorption (14,15) techniques in the past. It seems worth noting that NO molecules are physically similar to OH radicals (16,17) in terms of their molecular states but are chemically much more stable.…”

The Line Width of the EPR Signal of Gaseous Nitric Oxide as Determined by Pressure and Temperature-Dependent X-band Continuous Wave Measurements

“…But not only NO species adsorbed at some surface sites can be observed by EPR. Also desorbed NO gas shows a characteristic EPR signal [8,9]. The quantification of desorbed NO in EPR measurements is of great interest.…”