Nickel Filter Background Steps

Muzi

Hi everyone,
I'm trying to fit an XRD pattern of a Si standard that has steps in the background due to Ni filters. I implemented the routine posted on the TOPAS wiki, but I'm getting an error message: "Cannot find match for macro Cu6_Ni_Edge".
The program only runs if I disable the last three lines, but that doesn't give a good fit. Here is the Cu6_Ni_Edge macro I'm using:
Cu6_Ni_Edge
(
0.0001,
@, 0.00177`, ' Kbeta intensity
1.4, 1.8, ' min/max lam
,1.4879, ' edge
@, 375.28836_LIMIT_MIN_60, ' a_erf
@, 0.00000_LIMIT_MIN_0, ' b_exp
@, 0.01155, ' a_white
'@, 13.88745, ' b_white
'@, 1.27241, ' c_white
'@, 0.00588 ' edge_scale
)
prm !ab = 1129.50745 .36; : 406.62268
Absorption( !ab )

Could you please provide some guidance on how to properly fit the background steps caused by the Ni filters?

Thanks,
Muzi

rowlesmr

TOPAS is telling you it can't find a macro called Cu6_Ni_Edge that has the same number of arguments that you have given it.

The macro's signature is defined as

Cu6_Ni_Edge(
    vymin_on_ymax,
    ccuKb,          vcuKb,
    max_lam,
    cedge,          vedge,
    ca_white,       va_white,
    cb_white,       vb_white,
    ca_erf,         va_erf,
    cedge_extra,    vedge_extra
   )

which has 14 arguments

You are trying to call it with

Cu6_Ni_Edge
(
    0.0001,
    @,              0.00177`,
    1.4,  
    1.8,            ,
    1.4879,         @,
    375.28836,      @, 
    0.00000,        @, 
    0.01155,        @, 
    13.88745,       @, 
    1.27241,        @, 
    0.00588 
)

which has 19 arguments, so the lookup is working incorrectly.

You should try

Cu6_Ni_Edge
(
0.0001,
@, 0.00177`, ' Kbeta intensity
1.8, ' min/max lam
!edge ,1.4879, ' edge
@, 0.01155, ' a_white
@, 13.88745, ' b_white
@, 375.28836_LIMIT_MIN_60, ' a_erf
@, 0.00588 ' edge_scale
)

assuming that your comments line up with what the values of the arguments represent.

Muzi

Thanks rowlesmr! That's very helpful.