The secondary electrons peak provides high intensity compared to the XPS and UPS core-level intensities. NanoESCA takes advantage of this, using the high intensity peak for fast sample navigation provided by the PEEM mode. In addition a mercury arc lamp can be used to enhance this effect. Secondary electron mapping can be used for large and small area viewing of the sample with a field of view from > 600 µm to 5 µm.

A spectrum of photo-excited electron starts with the emission on-set at the low energy side and ends with the Fermi-edge at the high energy side. NanoESCA allows making use of the complete spectrum. Most commercially available spectrometers allow easy access to UPS and XPS energies while the low energy electrons end remains difficult to analyze with high lateral resolution.

In contrast NanoESCA gives access also to electrons starting from the sample with kinetic energies even below 0.1 eV utilizing a high extraction field of several thousand volts between sample and the entrance lens. As a result the information of the total spectrum width (from emission on-set to the Fermi edge) and the energy of the incident photons allow extracting the local work function quantitatively. This valuable information allows understanding the local chemistry and grain structure of the sample in greater detail.

A typical workflow for the analysis of an unknown sample profits from all three operations modes (shown right) finding answers to three questions:

Where are the interesting features?
Photoelectron Emission Microscope mode (PEEM)

Which elements are there and how much of them?
Small Spot Spectroscopy mode

What is the elemental map and chemical bonding?
Imaging ESCA-Mode