The effect of surface interaction on the performance of submillimeter atomic magnetometers*

We have studied the effect of surface interaction on the performance of submillimeter atomic magnetometers. We use an evanescent wave magnetometer with a coated cell of adjustable length. The cell length varies from a few millimeters to less than 100 $\mu m$. Two kinds of antirelaxation coatings are used: octadecyltrichlorosilane (OTS) and dichlorooctamethyltetrasiloxane (Surfasil). Sub-kHz linewidth can be achieved for a 100 micron thick OTS-coated cell. Magnetometers with coated ultra thin cells have superior performance in inhomogeneous magnetic fields, and can achieve a spatial resolution of better than 25~$\mu m$.