An experimental method for calibration of the plasmon mean free path

Abstract

SummaryTransmission electron microscopy specimens in the form of elongated, conical needles were made using a dual-beam focused ion beam system, allowing the specimen thickness to be geometrically determined for a range of thickness values. From the same samples electron energy loss maps were acquired and the plasmon mean free path (λ) for inelastic scattering was determined experimentally from the measured values of specimen thickness. To test the method λ was determined for Ni (174 ± 17 nm), α-Al 2 O 3 (143 ± 14 nm), Si (199 ± 20 nm) and amorphous SiO 2 (238 ± 12 nm), and compared both to experimental values of λ taken from the literature and to calculated values. The calculated values of λ significantly underestimate the true sample thickness for high accelerating voltages (300 kV) and large collection angles. A linear dependence of λ on thickness was confirmed for t/λ < 0.5-0.6, but this method also provides an approach for calibrating λ at sample thicknesses for which multiple scattering occurs, thus expanding the thickness range over which electron energy loss spectroscopy can be used to determine the absolute sample thickness (t/λ > 0.6). The experimental method proposed in this contribution offers a means to calibrate λ for any type of material or phase that can be milled using a focused ion beam system.

Kinetics and thermodynamics associated with Bi adsorption transitions at Cu and Ni grain boundaries

“…Calibration of the mean free path in Cu at 200 kV was performed following Ref. 42. Our experimentally determined mean free path is 135 6 15 nm, which agrees well with a predicted value of $130 nm from theoretical calculations.…”

A review of wetting versus adsorption, complexions, and related phenomena: the rosetta stone of wetting

“…With the introduction of dual-beam focused ion beam (FIB) systems, it is now possible to accurately prepare cross section samples from the center of small crystals equilibrated on substrates [56,57], and make accurate measurements of solid-solid interfacial energy and orientation relationships between the crystal and the substrate [58]. Furthermore, if the cross section transmission electron microscopy (TEM) sample is thin enough [59,60], more advanced TEM techniques can be used to determine the atomistic structure and chemistry of the interface for the same sample [61][62][63]. The size of the crystals must not be too small, since clusters in the nanometer length scale may exhibit variance of equilibrium shapes depending on the particle size and hetero-epitaxial related interfacial stress [64][65][66][67].…”

Determination of the mean inner potential of cadmium telluride via electron holography

“…1(f), which shows a line profile extracted along QQ 0 . No problems with linearity were evident in the thin region (where surface plasmon effects might contribute strongly 10 ) or in the thick region (where multiple scattering may cause non-linear behavior 11 ). These data confirm the validity of EELS measurements of CdTe thickness in this range.…”

“…11,12 Additionally, Gan et al recently measured the mean free path of ZnTe (a rather similar material to CdTe) to be 46 nm (Ref. 13) via holography amplitude measurements.…”