Jj. Bercier et al., EVIDENCE FROM NMR FOR TEMPERATURE-DEPENDENT BARDEEN-FRIEDEL OSCILLATIONS IN NANOMETER-SIZED SILVER PARTICLES, Journal of physics. Condensed matter, 5(44), 1993, pp. 571-576
The abrupt discontinuity of the background in the semi-infinite jelliu
m results in a decaying oscillatory (Bardeen) spatial response of the
electron gas. Related phenomena are the Friedel oscillations around an
impurity in a metal, and the Ruderman-Kittel coupling between two loc
alized magnetic moments embedded in a sea of conduction electrons. We
have found that the Ag-109 (I = 1/2) NMR linewidth in nanometre-sized
supported (and therefore isolated) silver particles shows a size effec
t that may be due to Bardeen-Friedel oscillations. The linewidth is al
so temperature dependent, in a way that cannot easily be explained as
an effect of paramagnetic impurities; we suggest that thermal vibratio
ns, known to have comparatively large amplitudes in small particles, w
ash out the abruptness in the background-charge discontinuity, and thu
s diminish the amplitude of the oscillations.