Hight Resolution Angle Resolved Photoemission (Cx2)

Caption: Drawing of the CASSIOPEE High Resolution Angle Resolved Photoemission experiment.

Beam size

The beam is focussed by a pseudo-Wolter optics located just before the experimental chamber. It consists in a spherical mirror followed by a toroidal mirror.

Caption: Schematic view of the pseudo-Wolter, focussing the beam in the CASSIOPEE High Resolution Angle Resolved Photoemission experiment

The size of the beam depends on the photon energy, but is always of the order of some tens of microns. Some ray tracing calculations are show below.

Caption: Beam size in the High Resolution Angle Resolved Photoemission experiment at 9 eV, calculated by ray tracing. The dimensions of the beam are 70 (horizontal) x 90 (vertical) µm2.

Caption: Beam size in the High Resolution Angle Resolved Photoemission experiment at 25 eV, calculated by ray tracing. The dimensions of the beam are 50 (horizontal) x 30 (vertical) µm2.

Caption: Beam size in the High Resolution Angle Resolved Photoemission experiment at 100 eV, calculated by ray tracing. The dimensions of the beam are 40 (horizontal) x 20 (vertical) µm2.

Analyzer

The CASSIOPEE High Resolution Angle Resolved Photoemission experiment is equipped with a Scienta R4000 electron analyzer, whose angular acceptance is ±15° (Scienta Wide Angle Lens). This analyzer can be mounted with its slits either vertical or horizontal.

Sample holder

The High Resolution Angle Resolved Photoemission experiment is equipped with a 4 axis sample holder, with manual X, Y and Z translation and a manual rotation. The sample can be cooled down to 5 K thanks to a liquid He cryostat. This sample holder has been designed and built at the Laboratoire de Physique des Solide (Orsay, France) by Véronique Brouet, Gilles Guillier and Alessandro Nicolaou. When this sample holder is in use, the Scienta analyzer is mounted with its slits vertical. The 30° vertical angular acceptance and the  rotation of the sample allow to scan a large part of the reciprocal space.

Caption: View inside the High Resolution Angle Resolved Photoemission experiment, with the cryostat shield and the nose of the Scienta R4000 electron analyzer on the left.

A fully motorized, six degrees of freedom (X, Y and Z translations, ,  and tilt rotations) helium-cooled sample holder is currently developed and should be available in September 2010. This sample holder has been designed and built by the Axess Tech Company (Saint-Cannat, France).

Caption: Drawing of the Axess Tech six degrees of freedom sample holder.