Set x axis at y=0 on the following plot?

Questions
1

I plotted this graph

WhatsAppImage2019-01-10at16.23.19.jpeg
WhatsAppImage2019-01-10at16.23.19.jpeg803Ă—438 17.9 KB

with this command:

Labeled[Show[
  Plot[in, {r, 0, a}, 
   Ticks -> {{{a, "a"}, {3 a, "3a"}, {5 a, "5a"}, {7 a, "7a"}, {9 a, 
       "9a"}, {12 a, "12a"}}, {0, 2.2*^-11}}, PlotRange -> All],
  Plot[out, {r, a, 12 a}], PlotRange -> All, AxesStyle -> Black, 
  AxesLabel -> {r, "Intensity"}, 
  LabelStyle -> Directive[Bold, Medium]], Style["HE11", Bold, Large]]

in is a function to be plotted between 0 to a,

and

out is a function to be plotted between a to 12a.

As you can see, the r (horizontal axis) doesn’t lie with the y=0 line. How can I fix this?

Should I instruct the PlotRange option in the Show function, rather than inside the second
Plot? (I tried, but no graphics was produced).

2

I can’t evaluate your code on my machine (don’t have the necessary data), but are you looking for AxesOrigin?

Labeled[Show[
  Plot[in, {r, 0, a}, 
   Ticks -> {{{a, "a"}, {3 a, "3a"}, {5 a, "5a"}, {7 a, "7a"}, {9 a, 
       "9a"}, {12 a, "12a"}}, {0, 2.2*^-11}}, PlotRange -> All], 
  Plot[out, {r, a, 12 a}], PlotRange -> All, AxesStyle -> Black, 
  AxesLabel -> {r, "Intensity"}, LabelStyle -> Directive[Bold, Medium],
  AxesOrigin -> {0, 0}
  ], Style["HE11", Bold, Large]]
3

Yep, that’s the one.

Thanks very much.