diff --git a/beamtime/nappBackground.m b/beamtime/nappBackground.m
index 77434f6..012fcab 100644
--- a/beamtime/nappBackground.m
+++ b/beamtime/nappBackground.m
@@ -1,4 +1,4 @@
- function DataTable = nappBackground(DataTable,varargin)
+function DataTable = nappBackground(DataTable,varargin)
 %nappBackground determines and subtracts the background from PE or XAS spectra
 %
 %   FileList = nappBackground(FileList,energyStart,energyEnd);
@@ -39,7 +39,7 @@
 defaultTableVariable        = 'spectrum_countsPerSecond';
 expectedTableVariable       = {'spectrum_counts','spectrum_countsPerSecond','spectrum_countsNorm'};
 defaultMode                 = 'mean';
-expectedMode                = {'mean','linfit'};
+expectedMode                = {'mean','linfit','exponential','mean, divide','linfit, divide','exponential, divide'};
 defaultTableSelection       = true(size(DataTable,1),1);
 defaultShowFigures          = 'on';
 expectedShowFigures         = {'on','off'};
@@ -81,16 +81,56 @@ existColumn = strcmp('logBackgroundDate',DataTable.Properties.VariableNames);
 if ~any(existColumn)
     DataTable.logBackgroundDate = cellstr(repmat(' ',size(p.Results.DataTable,1),1));
 end
+% add empty variable to table
+existColumn = strcmp('spectrum_countsNorm',DataTable.Properties.VariableNames);
+if ~any(existColumn)
+    DataTable.spectrum_countsNorm = cell(size(DataTable,1),1);
+end
 
 
 % repeat this for all columns in input.
 for ii = 1:size(p.Results.DataTable(p.Results.tableSelection,:),1)
     if contains(p.Results.energyScale,'kinetic')
         % LINEAR FIT
-        if contains(p.Results.mode,'linfit')
+        if startsWith(p.Results.mode,'linfit')
             disp('linfit not yet supported')
-            % MEAN
-        else
+            % declining background
+        elseif contains(p.Results.mode,'exponential')
+            [xData, yData] = prepareCurveData(p.Results.DataTable(p.Results.tableSelection,:).scientaEkin_eV{ii},p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii});
+
+            % Set up fittype and options.
+            ft = fittype( 'exp2' );
+            excludedPoints = excludedata( xData, yData, 'domain',[p.Results.energyStart(1) p.Results.energyEnd(1)] );
+            if size(p.Results.energyStart,2) ==2 && size(p.Results.energyEnd,2) ==1
+                excludedPointsEins = excludedPoints;
+                clearvars excludedPoints 
+                excludedPointsZwei = excludedata( xData, yData, 'domain',[xData(1) p.Results.energyStart(2)] );
+                excludedPoints = excludedPointsEins & excludedPointsZwei;
+            end
+            
+            opts = fitoptions( 'Method', 'NonlinearLeastSquares','Exclude', ~excludedPoints );
+            opts.Display = 'Off';
+
+            % Fit model to data.
+            [fitresult, ~] = fit( xData, yData, ft, opts );
+            if contains(p.Results.showFigures,'on')
+                % Plot fit with data.
+                figure( 'Name', 'untitled fit 1' );
+               plot( fitresult, xData, yData, excludedPoints );
+               % legend( h, 'y vs. x', 'Excluded y vs. x', 'untitled fit 1', 'Location', 'NorthEast', 'Interpreter', 'none' );
+                % Label axes
+                xlabel( 'kinetic energy [eV]', 'Interpreter', 'none' );
+                ylabel( 'PE intensity', 'Interpreter', 'none' );
+                grid on
+                title(p.Results.DataTable(p.Results.tableSelection,:).name{ii},'Interpreter','none')
+            end
+            if endsWith(p.Results.mode,'divide')
+                tmp{ii,1} = p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii}./fitresult(p.Results.DataTable(p.Results.tableSelection,:).scientaEkin_eV{ii});
+          
+            else
+                tmp{ii,1} = p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii}-fitresult(p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii});
+            end
+        elseif startsWith(p.Results.mode,'mean')
             b_1         = find(p.Results.DataTable(p.Results.tableSelection,:).scientaEkin_eV{ii} >= p.Results.energyStart,1);
             b_2         = find(p.Results.DataTable(p.Results.tableSelection,:).scientaEkin_eV{ii} >= p.Results.energyEnd,1);
 
@@ -150,7 +190,7 @@ for ii = 1:size(p.Results.DataTable(p.Results.tableSelection,:),1)
                 % prepare Data
 
                 [xData, yData] = prepareCurveData( p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}, ...
-                p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii});
+                    p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii});
                 % MEAN
                 b_1 = find(xData >= p.Results.energyStart,1);
                 b_2 = find(xData >= p.Results.energyEnd,1);
@@ -159,7 +199,7 @@ for ii = 1:size(p.Results.DataTable(p.Results.tableSelection,:),1)
             elseif p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}(1) > p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}(end)
                 % prepare Data
                 [xData, yData] = prepareCurveData( p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}, ...
-                p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii});
+                    p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii});
                 % MEAN
                 b_1 = find(xData <= p.Results.energyStart,1);
                 b_2 = find(xData <= p.Results.energyEnd,1);
@@ -170,18 +210,22 @@ for ii = 1:size(p.Results.DataTable(p.Results.tableSelection,:),1)
             end
 
 
-        tmp(ii,1) = cellfun(@(x) x-b_mean,p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable)(ii),'UniformOutput',false);
+            tmp(ii,1) = cellfun(@(x) x-b_mean,p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable)(ii),'UniformOutput',false);
         end
-        
+
 
     end
 end
 
 % fill selected rows
-DataTable(p.Results.tableSelection,:).(p.Results.tableVariable)                  = tmp;
+if endsWith(p.Results.mode,'divide')
+    DataTable(p.Results.tableSelection,:).spectrum_countsNorm                        = tmp;
+else
+    DataTable(p.Results.tableSelection,:).(p.Results.tableVariable)                  = tmp;
+end
 % write log to table
 DataTable.logBackgroundMode(p.Results.tableSelection,:)                  = cellstr(repmat(p.Results.mode,size(p.Results.DataTable(p.Results.tableSelection,:),1),1));
-DataTable.logBackgroundRange(p.Results.tableSelection,:)               = repmat([p.Results.energyStart p.Results.energyEnd],size(p.Results.DataTable(p.Results.tableSelection,:),1),1);
+DataTable.logBackgroundRange(p.Results.tableSelection,:)               = repmat([p.Results.energyStart(1) p.Results.energyEnd],size(p.Results.DataTable(p.Results.tableSelection,:),1),1);
 DataTable.logBackgroundDate(p.Results.tableSelection,:)                   = cellstr(repmat(datestr(now),size(p.Results.DataTable(p.Results.tableSelection,:),1),1));
 
 end
\ No newline at end of file