Topology measurements of metal nanoparticles with 1 nm accuracy by Confocal Interference Scattering Microscopy

Abstract

We present a novel scattering microscopy method to detect the orientation of individual silver nanorods and to measure their relative distances. Using confocal microscopy in combination with either the fundamental or higher order laser modes, scattering images of silver nanorods were recorded. The distance between two individual nanorods was measured with an accuracy in the order of 1 nm.We detected the orientation of isolated silver nanorods with a precision of 0.5 degree that corresponds to a rotational arch of about 1 nm. The results demonstrate the potential of the technique for the visualization of non-bleaching labels in biosciences.

Nanoscale characterization of single Au nanorods by confocal microscopy

“…Despite the remarkable differences in the image quality, for both studied interfaces the precision of our technique is comparable (see Table 1). A standard deviation of the particles' orientations D# of 18 (corresponding to a rotational arch of 1 nm for a long axis of 54 nm) was achieved together with relative errors Dd XY /d XY in the distances between two particles below 1% in total accordance with the accuracy recently published [29]. Note that the higher image quality in aqueous media (see Fig.…”

“…3. Contrary to the results presented in reference [29], the rotation was spontaneous and not known a priori. A larger area with several particles is depicted in the upper row of Fig.…”

“…For more details please refer to Ref. [29]. Note that the model function does not include any physics but is useful to determine the particle's orientation.…”

“…Combining confocal interference scattering microscopy (CISM [27]) with higher order laser modes (CISM-HOLM) allows to determine the orientation of single metallic nanorods and to distinguish differently shaped particles [28][29][30]. In this study, we examined the influence of the refractive index of the surrounding medium on the image contrast and quality.…”

Complete three-dimensional optical characterization of single gold nanorods

“…Several methods like dark field imaging [17], photothermal imaging [18] or two-photon luminescence [19] are suitable to image single metal nanoparticles down to a few nanometers in size. Imaging is also useful for determining the topology and tracking noble metal nanoparticles [1,2,20,21]. For example, some of the mentioned techniques are capable to measure the 2D [1,2,22] or 3D orientation [23] of plasmonic nanoparticles.…”