Attosecond nanoplasmonic-field microscope

Nanoplasmonics deals with collective electronic dynamics on the surface of metal nanostructures, which arises as a result of excitations called surface plasmons. This field, which has recently undergone rapid growth, could benefit applications such as computing and information storage on the nanoscale, the ultrasensitive detection and spectroscopy of physical, chemical and biological nanosized objects, and the development of optoelectronic devices. Because of their broad spectral bandwidth, surface plasmons undergo ultrafast dynamics with timescales as short as a few hundred attoseconds. So far, the spatiotemporal dynamics of optical fields localized on the nanoscale has been hidden from direct access in the real space and time domain. Here, we propose an approach that will, for the first time, provide direct, non-invasive access to the nanoplasmonic collective dynamics, with nanometre-scale spatial resolution and temporal resolution on the order of 100 attoseconds. The method, which combines photoelectron emission microscopy and attosecond streaking spectroscopy, offers a valuable way of probing nanolocalized optical fields that will be interesting both from a fundamental point of view and in light of the existing and potential applications of nanoplasmonics.