Figure 1: Photograph of the 1.4.4 FTIR spectromicroscopy endstation.

Introduction

The FTIR instrumentation for Beamline 1.4.4 is shown in Figure 1 and consists of a Nicolet Nexus 870 FTIR bench (to the right), and a Continuμm XL imaging microscope (to the left). One of the primary reasons for doing infrared spectroscopy at a synchrotron light source is the large enhancement in brightness (flux per unit area). This brightness advantage is most beneficial when focusing the light to a very small spot size. We have achieved diffraction-limited spot sizes in the mid-IR using Beamline 1.4.4 (see article).

When you first arrive at the beamline there are several things to do. The main FTIR bench and the IR microscope are always kept powered on, but the IR detector inside the microscope needs to be cooled by filling its dewar with liquid nitrogen. The Continuum XL imaging microscope has two detectors, a single element MCT A* detector and a 28 element focal plane array (FPA) detector. The FPA is not functional with the synchrotron, but can be used with the internal source to obtain fast images with a spatial resolution of ~ 9 μm using the 32x objective. For the best signal to noise and spatial resolution, however, the synchrotron source is required. The rest of this manual will concentrate on how to use the microscope with the synchrotron source. If you are interested in using the array system, please contact Mike or Hans.

To fill the MCT detector,

• Put on safety glasses and cryogenic gloves.
• Remove the cap at the position labeled MCT
• Insert the funnel into the dewar (see figure 2).
• Fill the green thermos labeled ‘Nicolet’ with liquid nitrogen using the gray 4 L dewar (the thermos holds approximately the correct amount of liquid nitrogen to fill the MCT detector’s dewar and is easier to handle).
• Pour the liquid nitrogen from the thermos into the funnel. The entire contents of the thermos will not fit in the funnel, so you will have to refill it several times.

Figure 2: Cooling the MCT detector with liquid nitrogen.