Answer
The excitation decreases the probability of detecting the electron in a small length of the x axis at the center of the well.
Work Step by Step
In Figure 39-6, we can see that the graph of the probability density for $n = 1$ (the ground state) has a peak near the center. This shows that there is a high probability of finding the electron near the center of the well.
The graph of the probability density for $n = 2$ (first excited state) has a trough near the center. This shows that there is a low probability of finding the electron near the center of the well.
Therefore, the excitation decreases the probability of detecting the electron in a small length of the x axis at the center of the well.
