Useful analysis method of angle-resolved ultraviolet photoemission spectra

在HOPG石墨和MoS_2衬底上测量了双（1,2,5-噻二唑）-铑喹啉（1,3-二噻唑）（BTQBT）和萘的角分辨紫外发射光谱（ARUPS）。通过对光电子强度的发射角依赖关系的定量比较，我们成功地确定了这种大型有机分子的极性和方位角。在这些计算中，我们采用了独立原子中心（IAC）近似，其中包含了发射原子对光电子的自散射。此外，在考虑自散射和单散射的情况下，将全价带光谱的发射角依赖性与计算值进行了比较。计算中还考虑了光电子的现象学诱导平均自由程的影响。我们正在开发的计算程序（IAC31）使我们能够确定大分子有机分子薄膜中的定量分子取向。

We measured Angle-resolved ultraviolet photoemission spectra (ARUPS) for the thin films of bis (1,2,5-thiadiazolo)-rho-quinobis (1,3-dithiole) (BTQBT) and naphthacene on HOPG graphite and MoS_2 substrate. Through the quantitative comparison between the observed and calculated take-off angle dependencies of the photoelectron intensities, we succeeded in determining the polar and azimuthal orientations of such large organic molecules. In these calculations, we applied the independent-atomic-center (IAC) approximation which includes the self-scattering of the photoelectrons by the emitting atoms. Further, the measured take-off angle dependence of the full valence-band spectra is compared with the calculated one by considering both the self- and single-scattering. The effect of the phenomenologically induced mean free path of the photoelectrons is also included in the calculation.Our developing calculation program (IAC31) enables us to determine the quantitative molecular orientation in the thin films of the large organic molecules.