The photodetachment of H- in a gradient electric field near an elastic surface has been studied on the basis of the closed-orbit theory, especially discuss the influence of the elastic surface on the photodetachment cross section of H- in a gradient electric field. It is demonstrated that the photodetachment of H- in a gradient electric field near an elastic surface is related to the position of the elastic surface. If the elastic surface was set far away from H-, it has a minor influence on the photodetachment cross section and the cross section approximates to the photodetachment of H- in a gradient electric field without the elastic surface. However, with the decrease of the ion-surface distance, its influence becomes apparent, the oscillating amplitudes of the photodetachment cross section becomes larger. Besides, we compare the cases when the elastic surface lies in the Z＞0 space and in the Z＜0 space. The results suggests that the oscillatiory structure becomes more complex when elastic surface lies in the Z＜0 space rather than in the Z＞0 space. Therefore, we can control the photodetachment of H- in a gradient electric field by changing the position of the elastic surface. We hope that our results will be useful in understanding the photodetachment process of negative ions in non-uniform field near surfaces.
