## 3 Results and Discussion  
Figure 1a shows the dependences of the coefficients of light conversion into longitudinal photocurrent \(\eta_{\text{x}}\) on the angle of incidence \(\alpha\) for linear and circular polarizations, measured according to the sketch of experimental arrangements presented in the upper frame. It can be seen that the photocurrent is absent at normal incidence of the radiation on the film (\(\alpha\) = 0). The photocurrent changes polarity when the sign of the angle of incidence changes, increases in absolute value with an increase in the modulus of \(\alpha\), takes its extreme values at angles \(\mid\alpha\mid\approx\) 66-68\({}^{\circ}\), and disappears at a grazing incidence of radiation on the film. Thus, the longitudinal photocurrent for linear and circular polarizations is described by an odd function of the angle \(\alpha\):  
\[\eta_{\text{x}}(\alpha)=-\eta_{\text{x}}(-\alpha). \tag{1}\]With linear polarization, the dependence of \(\eta_{\rm x}\) on the polarization azimuth \(\Phi\) (the angle between the plane of polarization and the radiation incidence plane on the film \(\sigma\)) at a fixed \(\alpha\) is described by an even function:  
\[\eta_{\rm x}(\alpha,\Phi)=\ \eta_{\rm x}(\alpha,\Phi=0)\cos^{2}, \tag{2}\]  
where \(\eta_{\rm x}(\alpha,\Phi=0)\) is the conversion coefficient at a given \(\alpha\) and \(\Phi=0\). It should be noted that \(\Phi=0\) corresponds to \(p\)-polarized radiation. All this is clearly seen from the dependence \(\eta_{\rm x}(\Phi)=\eta_{\rm x}(\alpha,\Phi=0)\cos^{2}\Phi\) obtained at \(\alpha=43.5^{\circ}\), where \(\eta_{\rm x}(\alpha,\Phi=0)=6.7\) mA/mJ (see Figure 1b). From Equation (2) it follows that \(\eta_{\rm x}(\alpha=43.5^{\circ},\Phi=90^{\circ})=0\), i.e., no photocurrent is generated at \(s\)-polarization. Experiments have shown that this equation  
Figure 1: The light to longitudinal photocurrent conversion coefficient \(\eta_{\rm x}\) as a function of (**a**) the light incidence angle \(\alpha\) on the film at linear (\(p\)-polarization) and circular polarizations (points denote experimental results, curves denote fitting with \(\eta_{\rm x}=35.37\sin 2\alpha/(1.76\cos\alpha+1)^{2}\) and \(\eta_{\rm x}=15.68\sin 2\alpha/(1.75\cos\alpha+1)^{2}\) for linear and circular polarization, respectively) and (**b**) the azimuth of the polarization plane \(\Phi\) at \(\alpha=43.5^{\circ}\) (dots denote experimental results, curve denotes fitting with \(\eta_{\rm x}(\Phi)=6.7\cos^{2}\Phi\); orientations of the polarization plane are shown at the top). The insets show the sketches of the experimental setups: **k** and **E** are the wave vector and the electric field vector of the incident radiation, respectively; \(\sigma\) is the plane of incidence; \(\alpha\) is an angle of incidence; **n** is the normal to the film surface; **A** and **B** are the measuring electrodes; x, y are the axes of the rectangular coordinate system; the x and x\({}^{\prime}\) axes lie in the \(\sigma\) plane (\(x^{\prime}\perp\textbf{k}\), the x axis is perpendicular to the electrodes **A** and **B**); \(\Phi\) is the angle between the x\({}^{\prime}\) and **E**. is valid for any \(\alpha\). Figure 2a shows the dependence of the conversion coefficient of light into transverse photocurrent \(\eta_{y}\) on the angle of incidence \(\alpha\) for linearly polarized radiation at polarization azimuth \(\Phi=-45^{\circ}\), obtained using the experimental setup shown in the upper inset to this figure. It can be seen that, similarly to the angular dependence of the longitudinal photocurrent, the experimental dependence \(\eta_{y}(\alpha)\) is described by an odd function, i.e.