Analysis of nanometer-sized aligned conical pores using small-angle x-ray scattering

Abstract

Small-angle x-ray scattering (SAXS) was used to quantitatively study the morphology of aligned, monodisperse conical etched ion tracks in thin films of amorphous SiO 2 with aspect ratios of around 6 : 1 and in polycarbonate foils with aspect ratios of around 1000 : 1. This paper presents the measurement procedure and methods developed for the analysis of the scattering images and shows results obtained for the two material systems. To enable accurate parameter extraction from the data collected from conical scattering objects, a model fitting the two-dimensional (2D) detector images was developed. The analysis involved fitting images from a sequence of measurements with different sample tilts to minimize errors, which may have been introduced due to the experimental setup. The model was validated by the exploitation of the geometric relationship between the sample tilt angle and the cone opening angle, to an angle observed in the features of the SAXS images. We also demonstrate that a fitting procedure for 1D data extracted from the scattering images using a hard cylinder model can also be used to extract the cone size. The application of these techniques enables us to reconstruct the cone morphologies with unprecedented precision.

Highly Rectifying Conical Nanopores in Amorphous SiO2 Membranes for Nanofluidic Osmotic Power Generation and Electroosmotic Pumps

“…58 The nanopore etching process is very reproducible, as demonstrated previously for etch pits in thin films of a-SiO 2 . 44,56,58 This technique has now been translated to a-SiO 2 membranes. The biggest variance between membranes is the number of pores for low irradiation fluences.…”

“…These so-called ion tracks are more susceptible to chemical etching than the undamaged material. After irradiation, the membrane was taped to a silicon wafer using Kapton tape and immersed in 2.5% hydrofluoric acid at room temperature, which removes material along the track thus at a higher rate than the surrounding matrix (ii) . The setup used for etching is described in more detail in the Supporting Information (Figure S1).…”

Highly Rectifying Conical Nanopores in Amorphous SiO2

“…After irradiation, the membrane was taped to a silicon wafer using Kapton tape and immersed in 2.5 % hydroflouric acid at room temperature, which removes material along the track thus at a higher rate than the surrounding matrix (ii). 50 This process creates highly uniform conical nanopores in the thin a-SiO 2 windows. To stop the etching, the membranes were rinsed with and stored in demonised water until they were characterised.…”

“…In this work, we present a system of conical nanopores in thin amorphous SiO 2 (a-SiO 2 ) membranes fabricated using ion track etching. Our membranes feature conical nanopores that exhibit opening angles far greater than those in track etched polymers, 49,50 while being an order of magnitude thinner. We are able to either manufacture single pores or multipores with adjustable pore density on large areas.…”

Etched track profiles for relativistic 7 GeV silicon and 17.48 GeV Nickel ions in PADC detector: The case study of convex track walls

“…Spohr, 1990 ). The shape of pores and their influence on membrane capabilities was studied by many authors these last decades (Apel et al, 2003;Clochard et al, 2007;Ferain and Legras, 2001;Hadley et al, 2020;Siwy et al, 2003;Tung et al, 2001). Some of us have recently published data in relation with the shape and size of micro-tubes produced by high energy ion irradiation on thick PADC polymer processed in strong etching solution (Awad et al, 2020b).…”