# Mike Wong

Online site for SAM-related scripts contributed by Mike Wong (generally
atmospheric). See also [ Melissa Trainer\'s page](Mtrainer "wikilink").

### Igor scripts for SAM data anaylsis

#### Background Correction
Things to do to your data before using    
this BG script:                       
-   Import SAM data  into Igor as     waves: one wave  for the time     series, one for  the cps          
-   Apply your own   deadtime         correction to    the data         
-   Figure out what  experiment       interval you\'ll use for the BG   correction,      convert to sec   if needed        
-   Determine        whether BG       interval is      better fit by a  constant or a    decaying         exponential   

What this BG script  does:        

-   Fit BG to        selected         interval         
-   Create a new,    BG-corrected     wave             
-   Create a new     BG-uncertainty   wave (same value at every point)  
-   BG correction    applied is       constant (i.e.,  choosing         exponential BG   only helps       determine        accurate         constant BG      level)           
-   BG uncertainty   is empirically   based on scatter in data within   BG region        
-   Some details of  BG fit are       stored in the    \"Notes\" field  of the new       BG-corrected     wave      

Example screen shot:

[![Bg.ipf.screenshot.png](http://wiki2.xina.io/uploads/images/gallery/2023-03/scaled-1680-/bg-ipf-screenshot.png)](http://wiki2.xina.io/uploads/images/gallery/2023-03/bg-ipf-screenshot.png)

#### Subtract Contamination

 Things to do to your data before using this subtraction script:
 
-   Import SAM data  into Igor as     waves: one wave  for the time     series, one for  the cps          
-   Apply your own   deadtime and     background       correction to    all data used                     
What this  subtraction script  does:  
-   Iterpolate       parent cps to    timesteps of     daughter m/z     
-   Create new wave, `[new] = [daughter] - frac * [parent]`,     where frac is    the              user-specified   expected         daughter/parent  count ratio                       
Example screen shot:

[![Killfrag.ipf.screenshot.png](http://wiki2.xina.io/uploads/images/gallery/2023-03/scaled-1680-/killfrag-ipf-screenshot.png)](http://wiki2.xina.io/uploads/images/gallery/2023-03/killfrag-ipf-screenshot.png)

#### Make Count Ratio

Things to do to your data before using this ratio script:          

-   Import SAM data  into Igor as     waves: one wave  for the time     series, one for  the cps          
-   Apply your own   deadtime and     background       correction to    all data used                     
What this ratio      script does:                       

-   Interpolate      numerator cps to timesteps of     denominator m/z  
-   Create new wave, ratio of the     input waves               

Example screen shot:

[![Makeratio.ipf.screenshot.png](http://wiki2.xina.io/uploads/images/gallery/2023-03/scaled-1680-/makeratio-ipf-screenshot.png)](http://wiki2.xina.io/uploads/images/gallery/2023-03/makeratio-ipf-screenshot.png)