Analyzing point spectra

To analyze spectral scans, I recommend using IDL - however, IDL is not installed on the cryo computer and therefore, the analysis has to be done on a different machine such as the beamline PC or xray1. You can do:

IDL> read_sm,'x1aic_14nov1999_0050.sm'
IDL> ev=1.239852/x_dist
IDL> khz=100.*image_data(*,*,1)/float(image_data(*,*,2))
IDL> plot,ev,khz			; this plots the raw data

IDL> plot, ev, -alog(I/I0)		; optical density

However, at this point the data are not saved entirely correctly, and the khz array should be re-sorted and plotted against the wavelength in nm:

IDL> l_nm=1000.*x_dist
IDL> n=n_elements(khz)
IDL> print,n
        2085
IDL> new_khz=fltarr(n)
IDL> for i=0,n-1 do new_khz(i)=khz(n-i-1)
IDL> plot,l_nm,new_khz

The spectra acquired by cj_spec2 are written to mapper files (extension .map). A spectrum file (e.g. 12feb1999i_005.map) will hold the energy and corresponding count rate, supposedly in kHz but I think there is an error by a factor of 10 or so. To read and plot a spectrum open IDL and do:

IDL> read_mapper, '12feb1999i_005.map', ev_i, i
IDL> read_mapper, '12feb1999i_006.map', ev_i0, i0
IDL> s = -alog(i/i0)
IDL> !x.title = 'eV'
IDL> !y.title = '-alog(I/I0)'
IDL> !p.title = 'cool title for plot'
IDL> plot, ev_i,s

You can determine peak positions by using the IDL routine ``plotpeak.pro''. If you type plotpeak at the IDL prompt, it will tell you how it works.

To print a spectrum, you have to go through the following steps:

IDL> set_plot, 'ps'
IDL> device, file = 'myspectrum.ps', xsize=4., ysize=3., /inch
IDL> plot, ev_i, s
IDL> device, /close
IDL> set_plot, 'x'
IDL> $ laser_x1 myspectrum.ps