vline[x_, h_] := 
      Graphics[{RGBColor[1, 0, 0], Line[{{x, 0},  {x, h}}]}]

Show[vline[0, 1]]

int[j_, a_] := (2  j + 1) Exp[-a j (j + 1)]

kBol := 1.38 10^-23;

hbar := 1.05*10^-34;

a := hbar^2/(2 Irot kBol T)

Irot = 3 *10^-47;

a /. T -> 300

plo[t_] := 
      Block[{T = t}, 
        Block[{jmax = Max[Floor[Sqrt[8/a]], 1]}, 
Show[
            Table[vline[j, int[j, a]],  {j, jmax}],  
            Axes -> True]]]

plo[300]

plo[1000]

disp := Display["t.ps",  #,  "EPS"]  &

Clear[figRot]; figRot[t_] := disp[plo[t]]

figRot[2000]

Save["figRot.m",  figRot]

!! figRot.m