Hi,
At 08:46 AM 7/7/00 +0100, Joe Hriljac wrote:
>When we faced the same decision (well, only one machine, UK oil money does
<snip>
I agree with Joe: I have a D500 with a Ge monochromator and a PSD. I don't
like the metal wire PSD as much as the quartz wire one as it imparts noise
to the data in excess of expected counting statistics but the machine
offers high resolution and stability with no alpha 2 or other junk. If the
machine is properly aligned and samples are properly mounted than one can
count on predicable delta d alignment curves. I believe the jury is still
out on high resolution / high accuracy data from mirror optics. They do
offer "freedom" from sample displacement errors; but there are additional
complications. I'll be speaking on this at Denver.
At 10:27 AM 7/7/00 +0200, Stan Gierlotka wrote:
1) Ge monochromator + PSD - no Ka2, extremely good counting statistics,
but somewhat broadened and uncertain peak shapes
2) Geobel mirror + LiF analyzer crystal - nice peak shapes down to very
low angles, very reliable peak positions but long counting times.
I disagree: If you've got "uncertain" peak shapes from your Ge
monochromator than you've got uncertainty somewhere in your
mounting/alignment of it. The Ge crystal can resolve the alpha 1 from the
alpha 2 without distortion; however, you do need a slit at the focal point
(line) to block scatter (the instructions supplied with the Siemens D500
setup don't mention this but the system is designed to allow it). The
mirror with an LiF analyzer is something I'd like to try out.
Regards,
Jim
James P. Cline [EMAIL PROTECTED]
Ceramics Division Voice (301) 975 5793
National Institute of Standards and Technology FAX (301) 975 5334
100 Bureau Dr. stop 8523
Gaithersburg, MD 20899-8523 USA
