Plane Grating Monochromator for synchrotron beamline applications 5 to 2300-eV Resolving power - 10,000 Index between 2 gratings under vacuum High resolution and high order rejection operation Angle of Incidence variable from 77 to 88.5-degrees UHV construction for 10^-10 torr operation Bakeable to 150-degrees C

McPherson PGM beamline monochromator as built for Center for Advanced Microstructures and Devices (CAMD) at Louisiana State University. We furnished and installed the complete beamline. The dual or triple grating PGM provides soft x-rays with high resolution and intensity from 5.4 - 2400Å (2300 - 5eV). Theoretical resolution with a 360g/mm grating is less than .01eV at 10eV and less than .1eV at 443eV. For performance details refer to "Preliminary Performance and Experiments from the High-Resolution Plane Grating Monochromator at CAMD," Z. Qu, K. Subramanian, N. Mainkar, R.L. Kurtz, R.L. Stockbauer, A. Mihill, and V. Saile, Nuclear Instruments and Methods in Physics Research A347, 299 (1994).

A complete series of unique McPherson products accompanied this installation. We provided high precision bilaterally adjustable slits, apertures, mirror manipulators, mounts and chamber systems. We also provided all mounting elements (floor stands, etc.) and software for control of the monochromator. The software operates the monochromator in several modes:

• high throughput - synchronously scans pre- mirror and grating angles to stay on grating blaze
• fixed focus - selects and drives pre- mirror and grating angle for desired wavelength
• high order rejection - selects and drives pre- mirror and grating angle for desired wavelength, and altering same to avoid multiple order effects
• constant wavelength - selects wavelength and drives pre- mirror and grating to maintain wavelength and find peak intensity / throughput
• independent - allows user to set any desired grating and pre- mirror angle and pre- mirror position for angle of incidence

The optics delivered with this beamline include a remote control, crossed pair of cylindrical mirrors, located behind the shield wall that collect light from the synchrotron and focus to the monochromator entrance slit. The entrance slit may be set for width and length under vacuum and is not cooled. Beyond the entrance slit, the light is reflected up to the selected plane grating by a movable mirror. This mirror moves along a line in such a way as to reflect the central ray to the grating. This pre- mirror changes the incidence angle of the monochromator and allows it to be operated in several modes (already described.) The selected grating diffracts the radiation to the focusing mirror. Between the two is a zero order baffle. The focusing mirror reflects the central ray and focuses it onto the exit slit, about 6-meters away. Finally, the selected light passes through the exit slit, and is focused into the sample chamber by a toroidal refocusing mirror.

Current McPherson ultra high vacuum (UHV) instruments are baked and RGA tested prior to shipment. Unique proven McPherson designs separate support members for chambers and precision grating mechanism. This for reduced sensitivity to vibration and thermal environmental factors. Scan grating angle by computer control and use rotary or laser tilt encoders for absolute feedback. Index gratings under vacuum, manually or by motor control. We have a variety of beam line instruments and accessories available.