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spectrum: Spectral analysis of the primary beam

The "spectrum" program can be used to make a specific scan through a single AMBI reflection to measure the effective spectrum of the primary beam.

Usage

The program is invoked by the command line:

spectrum [options] [xfilename]

The "xfilename" should either specify a denzo ".x" file, or a ".rmat" file from which the orientation matrix of a mounted AMBI crystal can be read.

The program will try to find a suitable AMBI reflection to measure in bisecting mode, such that a horizontal line on the detector will represent the effective spectrum of the primary beam, ranging from 2/3 of the current wavelength to 5/3 of the current wavelength over 90% of the width of the detector.

The possible options are the usual options for a unit cell specification, plus:

frametime=value: Specifies the exposure time in seconds.
hkl=h,k,l: Manually specify a reflection to use for the measurement. The program will assume that there is orthorhombic symmetry, and try all possible sign combinations.
psi=value: Specify a rotation around the reflection to be measured. This can be used to check for Renninger reflection.
minfrac=value and maxfrac=value: Specify edges of the spectrum other than the default 2/3 and 5/3 times the nominal wavelength. Please note that this is very experimental and not likely to be very accurate due to large approximations in the algorithms used.

The measured frame will be stored in the file "spectrum##f#.kcd", starting from the first scan number for which the "spectrum##f1.kcd" file does not exist on disk.

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